1-(12-Benzoyl-10-oxa-12-azatetracyclo-[6.3.1.02,7.0 9,11]dodeca-2,4,6-trien-1-yl)ethan-1-one - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2003)

1,2,4,5-Benzenetetracarboxylic acid: A versatile hydrogen bonding template for controlling the regioselective topochemical synthesis of head-to-tail photodimers from stilbazole derivatives - Ortega, Gabriela; Hernandez, Jesus; Gonzalez, Teresa; Dorta, Romano; Briceno, Alexander (Photochemical & Photobiological Sciences, 2018)

1,2,4-Triphospholyl Nickel Complexes: Evidence for a Dimerization Equilibrium that Includes a Sigma-Pi Rearrangement of the Triphospholyl Ligand - Zenneck, Ulrich; Heinemann, Frank Wilhelm; Pritzkow, Hans; Zeller, Matthias (Organometallics, 2000)
1-Trimethylstannyl-3,5-di(tert-butyl)-1,2,4-triphosphole (2) reacts efficiently with [(PPh3)2- NiCl2] or [(NO)(PPh3)2NiCl] by elimination of Me3SnCl and formation of 3,5-di(tert-butyl)-1,2,4-triphospholyl (1) nickel complexes. © 2000 American Chemical Society.
UnivIS-Import:2017-11-07:Pub.2000.nat.dchph.paoc22.124tri

1,2-Di-phosphetene, 1,2-Diphosphete and 1,3-Diphosphete Metal Complexes: Novel Access by Ring Contraction, Cyclodimerization and Intramolecular Redox Reactions - Zenneck, Ulrich; Heinemann, Frank Wilhelm; Kummer, Susanne; Seiss-Brandl, Udo (Organometallics, 1999)
UnivIS-Import:2017-11-07:Pub.1999.nat.dchph.paoc22.12diph

1,3-Bis(alpha-aminoisopropyl)benzene, meta-C6H4(CMe2NH2)(2): An N,N-bridging and N,C,N-cyclometalating ligand - Dahlenburg, Lutz; Treffert, Harald; Heinemann, Frank Wilhelm (Inorganica Chimica Acta, 2008)
Saponification of the bis(carbamic acid ester) 1,3-C6H4(CMe2NHCO2Me)(2) (1), made by the addition of methanol to commercial 1,3-C6H4(CMe2NCO)(2), yielded the meta-phenylene-based bis(tertiary carbinamine) 1,3-C6H4(CMe2NH2)(2) (2). Dinuclear [(eta(4)-1,5-C8H12) RhCl(2)mu-1,3-C6H4(CMe2NH2)(2)] (3) resulted from the action of 2 on [(eta(4)-1,5-C8H12)Rh(mu-Cl)(2)] in toluene. Combination of 2 with PdCl2 or K-2[PdCl4] gave the dipalladium macrocycle trans, trans-[mu-1,3-C6H4(CMe2NH2)(2)(2)(PdCl2)(2)] (4) along with cyclometalated [2,6-C6H3(CMe2NH2)(2)-kappa N, kappa C-1, kappa N'PdCl] (5). Substitution of PEt3 for the labile chlorido ligand of 5 afforded [2,6-C6H3(CMe2NH2)(2)-kappa N,kappa C-1, kappa N'Pd(PEt3)]Cl (6). The crystal structures of the following compounds were determined: bis(carbamic acid ester) 1, ligand 2 as its bis(trifluoroacetate) salt [1,3-C6H4(CMe2NH3)(2)](O2CCF3)(2), 2. (HAcf)(2), complexes 3 and 6, as well as 1,3-C6H4(CMe2OH)(2) (the diol analogue of 2). (C) 2007 Elsevier B.V. All rights reserved.
Keywords: 1; 3-Bis(alpha-aminoisopropyl)benzene; rhodium complex; palladium complexes; X-ray structure analysis

1,3-Dibenzoylimidazolidine-2-thione and 1,3-dibenzoyl-3,4,5,6-tetrahydropyrimidine-2(1 H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section C: Crystal Structure Communications, 2005)

1,5-Di-tert-butyl-3,3,7,7,10,10-hexaphenyl-2,4,6,8,9,11-hexaoxa-3,7, 10-trisila-1,5-digermabicyclo[3.3.3]undecane - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2003)

[18]Annulene put into a new perspective. - Lungerich, Dominik; Nizovtsev, Alexey; Heinemann, Frank Wilhelm; Hampel, Frank; Meyer, Karsten; Majetich, George; Schleyer, Paul V. R.; Jux, Norbert (Chemical Communications, 2016)
New insights into [18]annulene were gained by looking more closely at its X-ray structure, revealing a close face-to-face stacking of 3.16 Å in a herringbone-like crystal packing. Hexadehydro[18]annulene was co-crystalized in a benzene matrix, demonstrating the stabilizing role of intercalated solvent molecules in solid annulenes.

1D Chains of Diruthenium Tetracarbonyl Sawhorse Complexes - Fritsch, Nico; Wick, Christian; Waidmann, Thomas; Pflock, Stephan; Dral, Pavlo; Tucher, Johannes; Steiner, Christian; Shubina, Tatyana; Maier, Sabine; Clark, Timothy; Burzlaff, Nicolai (European Journal of Inorganic Chemistry, 2018)
The syntheses of five 1D coordination polymers containing the sawhorse-type unit [Ru-2(mu-OAc)(2)(CO)(4)] linked by various bridging N,N-donor ligands are reported. Various pi-conjugated linkers, such as trans-[1,2-bis(N-methyl)imidazol-2-yl]ethylene (trans-bie), pyrazine (pyz), 4,4-bipyridine (4,4-bipy) and 1,2-bis(4-pyridyl)ethylene (bpe) as well as the aliphatic linker 1,4-diazabicyclo[2.2.2]octane (DABCO), were applied in the syntheses. The formation of 1D coordination polymers was proven by crystal structure determinations of two of the polymeric materials. The geometries and electronic structures of all polymers were analysed further by CASSCF/CASPT2 and DFT calculations based on monomeric model compounds. Finally, first attempts regarding deposition of the 1D chain, the sawhorse fragment and/or the ligands on a highly ordered pyrolytic graphite surface, analysed by STM measurements, are also reported.
Keywords: Coordination polymers; Chain structures; Bridging ligands; N ligands; Ruthenium

1-Triorganylstannyl-1,2,4-triphosphole: A Versatile Educt for P-Rich Organophosphorous Cage Compounds and Pi-Complexes - Zenneck, Ulrich; Elvers, Achim; Heinemann, Frank Wilhelm; Wrackmeyer, B (Chemistry - A European Journal, 1999)
UnivIS-Import:2017-11-07:Pub.1999.nat.dchph.paoc22.1trior

2-(2,2-Dimethyl-1,3,2-dithiagermetan-4-ylidene)malononitrile - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

2-Amino-5-phenyl-1,3,4-thiadiazole at 110 K - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

2-Metalloeryptands of Iron and Gallium: Synthesis, structure, and properties [1] - Scheurer, Andreas; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2009)
Keywords: Metallocryptand; Self-assembly; N; O-Ligand; Triple helicate; Supramoleeular chemistry

[3.2.1] and [4.1.1] isomers of Lehn's [2.2.2] Cryptand: Prediction of ion selectivity by quantum chemical calculations XV** - Ćoćić, Dušan; Manaa, Aliya; Siegl, Selina; Puchta, Ralph; van Eldik, Rudi (Zeitschrift für Anorganische und Allgemeine Chemie, 2021)
Selective alkaline and earth alkaline metal ion encapsulation by two different Lehn-type cryptands, noted as [3.2.1] and [4.1.1], was predicted and between them compared on the DFT (B3LYP/LANL2DZp) basis set. Since these cryptands are isomers to the well-known [2.2.2] cryptand, the cation encapsulation selectivity of all three cages were compared. The ion selectivity and ability of the host to adjust their structure to successfully accommodate the metal ions, were based on energy and geometric criteria. Different lengths of O-Et-O-bridging arms provide an unsymmetrical cryptand host with great flexibility to accommodate large alkali and alkaline earth metal cations.
CRIS-Team Scopus Importer:2021-04-02
Keywords: cryptand; DFT-study; selective ion complexation

3-(2-Furyl)-4-(4-methoxyphenyl)-1 H-1,2,4-triazole-5(4H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

3,3-Bis(3,5-dimethylpyrazol-1-yl)propionic acid: A tripodal N,N,O ligand for manganese and rhenium complexes - Syntheses and structures - Peters, Liv; Hübner, Eike; Haas, T.; Heinemann, Frank Wilhelm; Burzlaff, Nicolai (Journal of Organometallic Chemistry, 2009)
The tripodal N,N,O ligands 3,3-bis(3,5-dimethylpyrazol-1-yl)propionic acid (Hbdmpzp) (1) and 3,3-bis(pyrazol-1-yl)propionic acid (Hbpzp) (2) form the "missing link" between the well-known bis(pyrazol-1-yl)acetic acids and related ligands with a longer "carboxylate arm". To illustrate the reactivity of this ligand, manganese and rhenium complexes bearing the ligand bdmpzp are reported. The complexes are compared to related compounds bearing other tripod ligands such as bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza) and 3,3-bis(1-methylimidazol-2-yl)propionate (bmip). Spectroscopic and structural data are used as a basis for comparison, as well as DFT calculations. Both ligands 1 and 2 and the complexes fac-[Mn(bdmpzp)(CO) ] (3) and fac-[Re(bdmpzp)(CO) ] (4) were characterised by X-ray crystallography. © 2009 Elsevier B.V. All rights reserved.

3-Benzyl-4-(4-chlorophenyl)-1H-1,2,4-triazole-5(4H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

3-Benzyl-4-(4-methylphenyl)-1H-1,2,4-triazole-5(4H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

3-butyl-4-(3-methyl-3-phenylcyclobut-1-yl)-1,3-thiazole-2(3H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2005)

3-Cyclohexyl-4-(3-methyl-3-phenylcyclobutyl)-1,3-thiazole-2(3H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2005)

(3E)-3-[(4-butylphenyl)imino]-1,3-dihydro-2H-indol-2-one - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2003)

(3E)-3-[(4-Hexylphenyl)imino]1H-indol-2(3H)-one - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2003)

(3-methyl-3-phenylcyclobutyl)(naphtho[2,1-b]furan-2-yl) methanone - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2006)
In the title compound, C24H20O2, C-H center dot center dot center dot O, C-H center dot center dot center dot pi and pi-pi interactions result in a three-dimensional supramolecular network.

4-(4-Chlorophenyl)-3-(furan-2-yl)-1H1,2,4-triazole-5(4H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

4,5-Bis(dialkylamino)-substituted imidazolium systems: facile access to N-heterocyclic carbenes with self-umpolung option. - Huber, Stefan; Heinemann, Frank Wilhelm; Audebert, Pierre; Weiss, Robert (Chemistry - A European Journal, 2011)
The first synthesis of 4,5-bis-(dimethylamino)-substituted imidazolium compounds was developed, which is based on the reaction of a 1,2-diamino-1,2-bis(phosphonio)ethene with lithiated formamidines. This represents the first application of this class of ethene derivatives for the preparation of heterocycles. These N-heterocyclic carbene (NHC) precursors show a remarkably reduced basicity and nucleophilicity of their NMe2 groups, which is due to the strong anomeric interactions of the latter with the imidazolium core. According to DFT calculations, these NHCs are capable of self-umpolung if sufficiently strong acceptor substituents are introduced at the carbene center. To test the self-umpolung capabilities of the NHCs, various substituents were attached to the carbene center and the obtained compounds were characterized by single-crystal X-ray analysis as well as quantum chemical computations. Strong acceptor substituents are required to induce self-umpolung, such as in the phosphonio-substituted derivative, for which partial self-umpolung was found. The N,N′-bis(4-dimethylaminophenyl)-substituted imidazolium compound represents a special case, as it incorporates as much as three two-step redox systems within the NHC framework. This will probably result in a high electronic flexibility of the corresponding nucleophilic carbenes, especially when they serve as ligands in transition metal complexes.

4-Azidobenzyl ferrocenylcarbamate as an anticancer prodrug activated under reductive conditions - Kinski, Elisa; Marzenell, Paul; Hofer, Walter; Hagen, Helen; Raskatov, Jevgenij A.; Knaup, Karl; Zolnhofer, Eva; Meyer, Karsten; Mokhir, Andriy (Journal of Inorganic Biochemistry, 2016)
Aminoferrocene-based prodrugs are activated in the presence of cancer-specific amounts of reactive oxygen species, e.g. H2O2, with the formation of products of two types: Fe-containing complexes, which catalyze generation of HO and O2-, and quinone methides, which alkylate glutathione and inhibit the antioxidative system of the cell. Both processes act synergistically by increasing the oxidative stress in cancer cells thereby leading to their death. However, in the activation step including the cleavage of a B-C bond one molecule of H2O2 is consumed that counteracts the desired effect of the products released from aminoferrocenes. We replaced an H2O2-sensitive trigger in original prodrugs with an azide group. This trigger is slowly reduced in the presence of glutathione with the formation of an unstable arylamine intermediate, which decomposes with the release of iron ions and iminoquinone methides. These products induce strong oxidative stress in cells as we confirmed using 2′,7′-dichlorodihydrofluorescin diacetate reagent in combination with flow cytometry. In this case the activation process does not consume H2O2. Correspondingly, we observed that the azide-containing prodrug is substantially more toxic towards human promyelocytic leukemia cell line HL-60 (IC50 = 27 ± 4 μM) than its H2O2-responsive analogue (IC50 > 50 μM).
CRIS-Team Scopus Importer:2020-09-14
Keywords: Azide; Cancer; Ferrocene; Prodrug; Reduction

(4R)-3-Hy-droxy-7-isopropyl-4-methyl-5,6-di-hydro-benzo-furan-2(4H)-one. - Heinemann, Frank Wilhelm; Herrera, Alberto Cesar; Agrifoglio, Giuseppe; Dorta, Romano; Pastrán, Jesús (Acta Crystallographica Section E: Structure Reports Online, 2014)
In the title compound, alternatively called α-hy-droxy-γ-alkyl-idenebutenolide, C12H16O3, two independent mol-ecules (A and B) crystallize in the asymmetric unit in each of which the 5,6-di-hydro-benzo ring has an envelope conformation. The torsion angle along the butadiene chain in the γ-alkyl-idenebutenolide core is -177.9 (2)° for mol-ecule A and 179.9 (2)° for mol-ecule B. In the crystal, O-H⋯O hydrogen bonds between hy-droxyl and carbonyl groups of adjacent independent mol-ecules form dimers with R (2) 2(10) loops.

5-(Furan-2-yl)-1,3,4-oxadiazole-2(3H)-thione - Heinemann, Frank Wilhelm; et al. (Acta Crystallographica Section E: Structure Reports Online, 2004)

A Bis(acetyl)-Bridged Platinum(II) Coordination Polymer as a Building Block for Diacetylplatinum(II) Complexes and Platina-beta-diketones - Schwieger, Sebastian; Heinemann, Frank Wilhelm; Wagner, Christoph; Kluge, Ralph; Damm, Cornelia; Israel, Gunter; Steinborn, Dirk (Organometallics, 2009)
The bis(acetyl)-bridged complex [Pt(COMe)(2)(n)] (2) has been prepared from the platina-beta-di ketone [Pt(2)(COMe)(2)H)(2)(mu-Cl)(2)] (1) with hexamethyldisilazane. Reactions of complex 2 with the monodentate P and N donors PPh(3), pyrazole (Hpz), pyridine (py), 4-methylpyridine (4-Mepy), and benzylamine (BnNH(2)) resulted in the formation of the cis-diacetylplatinum(II) complexes cis-[Pt(COMe)(2)L(2)] (L = PPh(3), 3; Hpz, 5; py, 6a; 4-Mepy, 6b; BnNH(2), 7). Reactions with the bidentate N donors 2,2'-bipyridine (bpy), dimethylglyoxime (H(2)dmg), and pyridazine (pydz) resulted in formation of the complexes cis-[Pt(CoMe)(2)(L boolean AND L)] (L boolean AND L = bpy, 4; H(2)dmg, 8) and [Pt(2)(COMe)(4)(mu-pydz)(2)] (9), respectively. Furthermore, complex 2 has been found to react with acids such as HX (X = Cl, Br), generated in situ from Me(3)SiX/H(2)O, acetylacetone (Hacac), and hexafluoroacetylacetone (Hhfacac) to yield the known platina-beta-diketone 1, the new dinuclear bromo-bridged platina-beta-diketone [Pt(2)(COMe)(2)H)(2)(mu-Br)(2)] (10), and new mononuclear platina-beta-diketones [Pt(COMe)(2)H)(L boolean AND L)] (L boolean AND L = acac, 11; hfacac, 12). All complexes were characterized by means of microanalysis and IR and NMR spectroscopy. X-ray diffraction analyses were performed for complexes 10-12, showing a two-dimensional network built up by closed-shell Pt center dot center dot center dot Pt (d(8)-d(8)) interactions and bifurcated hydrogen bonds in crystals of complex 10 as well as infinite platinum chains built up by closed-shell Pt center dot center dot center dot Pt (d(8)-d(8)) interactions in crystals of complexes 11 and 12. Complexes 8, 11, and 12 have further been analyzed by UV/vis and luminescence spectroscopy in solution and in the solid state as well as time-resolved photo-emf measurements. Additionally, quantum chemical studies on the DFT level of theory revealed very strong O-H center dot center dot center dot O hydrogen bonds in the platina-beta-diketones 10-12 (25.6-27.9 kcal/mol).

A bis(silylene)pyridine pincer ligand can stabilize mononuclear manganese(0) complexes: facile access to isolable analogues of the elusive d(7)-Mn(CO)(5) radical - Kalra, Shweta; Pividori, Daniel Maximilian; Fehn, Dominik; Dai, Chenshu; Dong, Shicheng; Yao, Shenglai; Zhu, Jun; Meyer, Karsten; Driess, Matthias (Chemical Science, 2022)
Using the potentially tridentate N,N'-bis(N-heterocyclic silylene)pyridine [SiNSi] pincer-type ligand, 2,6-N,N'-diethyl-bis[N,N'-di-tert-butyl(phenylamidinato)silylene] diaminopyridine, led to the first isolable bis(silylene)pyridine-stabilized manganese(0) complex, kappa(3)-[SiNSi]Mn(dmpe) 4 (dmpe = (Me2P)(2)C2H4), which represents an isolobal 17 VE analogue of the elusive Mn(CO)(5) radical. The compound is accessible through the reductive dehalogenation of the corresponding dihalido (SiNSi)Mn(II) complexes 1 (Cl) and 2 (Br) with potassium graphite. Exposing 4 towards the stronger pi-acceptor ligands CO and 2,6-dimethylphenyl isocyanide afforded the related Mn(0) complexes kappa(2)-[SiNSi]Mn(CO)(3) (5) and kappa(3)-[SiNSi] Mn(CNXylyl)(2)(kappa(1)-dmpe) (6), respectively. Remarkably, the stabilization of Mn(0) in the coordination sphere of the [SiNSi] ligand favors the d(7) low-spin electronic configuration, as suggested by EPR spectroscopy, SQUID measurements and DFT calculations. The suitability of 4 acting as a superior pre-catalyst in regioselective hydroboration of quinolines has also been demonstrated.
CRIS-Team WoS Importer:2022-07-29

Abrasion Indicators for Smart Surfaces Based on a Luminescence Turn‐On Effect in Supraparticles - Wenderoth, Sarah; Granath, Tim; Prieschl, Johannes; Wintzheimer, Susanne; Mandel, Karl (Advanced Photonics Research, 2020)
Slight mechanical damage on surfaces or coatings caused, for example, by shear stress, is hardly detectable by simple means. Therefore, shear stress indicator particles for the creation of “interactive and communicating” coatings are presented. These are core‐shell supraparticles obtained by a two‐step spray‐drying assembly process from nanoparticle dispersions. Three different types of nanoparticles are used to create the supraparticles: dye‐doped silica nanoparticles responsible for the fluorescence signal, iron oxide nanoparticles acting as a fluorescence absorber, and pure silica nanoparticles regulating the indicator sensitivity. The creation of two different types of indicator systems is feasible by changing the nanoparticle arrangements within the supraparticle: A turn‐off and a turn‐on system, which indicate—after incorporation into a coating—shear stress by the decrease or the increase in the fluorescence intensity, respectively. Herein, two different mechanisms compete with each other: on the one hand, the change in the fluorescence signal due to physical light‐absorbing effects, and on the other hand, the abrasion of luminescent material. The clear superiority of the turn‐on system to achieve a reliable signal is demonstrated in this work. With the particle systems, interactive and communicating surface coatings are established.<br
Keywords: abrasion indicators; communicating materials; smart surfaces; supraparticles; turn-on fluorescence

Abrasion Indicators for Smart Surfaces Based on a Luminescence Turn‐On Effect in Supraparticles - Wenderoth, Sarah; Granath, Tim; Prieschl, Johannes; Wintzheimer, Susanne; Mandel, Karl (Advanced Photonics Research, 2020)
Slight mechanical damage on surfaces or coatings caused, for example, by shear stress, is hardly detectable by simple means. Therefore, shear stress indicator particles for the creation of “interactive and communicating” coatings are presented. These are core-shell supraparticles obtained by a two-step spray-drying assembly process from nanoparticle dispersions. Three different types of nanoparticles are used to create the supraparticles: dye-doped silica nanoparticles responsible for the fluorescence signal, iron oxide nanoparticles acting as a fluorescence absorber, and pure silica nanoparticles regulating the indicator sensitivity. The creation of two different types of indicator systems is feasible by changing the nanoparticle arrangements within the supraparticle: A turn-off and a turn-on system, which indicate—after incorporation into a coating—shear stress by the decrease or the increase in the fluorescence intensity, respectively. Herein, two different mechanisms compete with each other: on the one hand, the change in the fluorescence signal due to physical light-absorbing effects, and on the other hand, the abrasion of luminescent material. The clear superiority of the turn-on system to achieve a reliable signal is demonstrated in this work. With the particle systems, interactive and communicating surface coatings are established.<br

Abrasive blasting of lithium metal surfaces yields clean and 3D structured lithium metal anodes with superior properties - Wolf, Andreas; Lorrmann, Henning; Flegler, Andreas; Wolf, Andreas J.; Guerﬁ, Abdelbast; Mandel, Karl; Giffin, Guinevere A. (Energy Technology, 2021)
Avoiding harmful passivation of the lithium metal surface during its implementation as an anode material is a challenge to its use in rechargeable lithium metal batteries. It is critical to control the chemical composition and the morphology of the native passivation layer and to avoid contamination by lubricants or other substances involved in the processing. Herein, abrasive blasting is used as a physical method to achieve clean and 3D-structured lithium metal electrodes. The careful choice of the abrasive agent and the blasting parameters results in well-controlled surface properties. The blasted lithium electrodes exhibit significantly lower overvoltages with values as low as 10 mV at 0.1 mA cm−2. Electrochemical impedance spectroscopy shows that blasted lithium has interface resistances that are up to five times smaller than those of untreated lithium. The effectiveness of blasting as a cleaning method is clear even in the case of thicker and highly resistive passivation layers occurring after exposure to ambient air.

Accurate tuning of ordered nanotubular platinum electrodes by galvanic plating - Roscher, Valentin; Licklederer, Markus; Schumacher, Johannes; Rios, Grisell Reyes; Hoffmann, Bjoern; Christiansen, Silke; Bachmann, Julien (Dalton Transactions, 2014)
Platinum nanotubes are created by galvanic deposition inside porous templates. The effects of the electrolyte's ion concentration and pH, of the applied potential and of the deposition duration on the morphology of the tubes are investigated systematically. The system provides a model electrode platform with accurately tunable geometry for the fundamental investigation of electrochemical transformations. For slow electrochemical reactions, we observe a linear increase of the galvanic current with the length of the nanotubes, and therefore with the specific surface area of the electrode. In contrast to this, inherently fast electrochemical transformations are diffusion-limited and give rise to the same current density independently of the geometry. These results delineate a strategy for optimizing the performance of electrochemical energy conversion devices systematically via nanostructuring the electrode surfaces.

A cis-Divacant Octahedral and Mononuclear Iron(IV) Imide - Searles, Keith; Fortier, Skye; Khusniyarov, Marat; Carroll, Patrick J.; Sutter, Jörg; Meyer, Karsten; Mindiola, Daniel J.; Caulton, Kenneth G. (Angewandte Chemie International Edition, 2014)
A rare, low-spin Fe-IV imide complex [(pyrr(2)py)-Fe=NAd] (pyrr(2)py(2-) = bis(pyrrolyl)pyridine; Ad = 1-adamantyl) confined to a cis-divacant octahedral geometry, was prepared by reduction of N(3)Ad by the FeII precursor [(pyrr(2)py)Fe(OEt2)]. The imide complex is low-spin with temperature-independent paramagnetism. In comparison to an authentic Fe-III complex, such as [(pyrr(2)py)FeCl], the pyrr(2)py(2-) ligand is virtually redox innocent.
Keywords: density functional calculations; iron; magnetic properties; Mossbauer spectroscopy; N ligands

A code with a twist: Supraparticle microrod composites with direction dependent optical properties as anti-counterfeit labels - Wintzheimer, Susanne; Granath, Tim; Eppinger, Antonia; Goncalves, Manuel Rodrigues; Mandel, Karl (Nanoscale Advances, 2019)
Superparamagnetic iron oxide nanoparticles can be assembled to form anisotropic microrod supraparticles with the assistance of a magnetic field during synthesis. Optionally, these iron oxide microrods can furthermore be coated with a thin silica shell. Due to their anisotropic structure, both microrod types can be aligned in a magnetic field while being dispersed in a matrix material which can be cured during the alignment of the microrods. In this way, an anisotropic magnetic composite is obtained. Interestingly, it was observed that the optical extinction properties for visible light in such a composite are direction dependent, which can be explained by using appropriate models based on Maxwell equations. Based on the understanding of this principle, a clever approach for a hidden code could be proposed which is obtained from mixing pure iron oxide and silica coated microrod supraparticles in such an anisotropic composite. The hidden code, which comes down to obtaining a single value eventually, can only be revealed when knowing that the system needs to be measured with a certain "twist".
CRIS-Team Scopus Importer:2020-04-02

A compact high pressure unit for UV-VIS-NIR spectroscopic measurements at pressures up to 400 MPa - van Eldik, Rudi; Khoshtariya, Dimitri E.; Igel, Peter; Weller, Manfred; Zahl, Achim; et al. (Review of Scientific Instruments, 2003)
UnivIS-Import:2015-03-09:Pub.2003.nat.dchph.laoc1.acompa

A complete series of uranium(iv) complexes with terminal hydrochalcogenido (EH) and chalcogenido (E) ligands e = O, S, Se, Te - Rosenzweig, Michael; Hümmer, Julian; Scheurer, Andreas; Lamsfus, Carlos Alvarez; Heinemann, Frank Wilhelm; Maron, Laurent; Mazzanti, Marinella; Meyer, Karsten (Dalton Transactions, 2019)
We here report the synthesis and characterization of a complete series of terminal hydrochalcogenido, U-EH, and chalcogenido uranium(iv) complexes, U≡E (with E = O, S, Se, Te), supported by the (Ad,MeArOH)3tacn (1,4,7-tris(3-(1-adamantyl)-5-methyl-2-hydroxybenzyl)-1,4,7-triazacyclononane) ligand system. Reaction of H2E with the trivalent precursor [((Ad,MeArO)3tacn)U] (1) yields the corresponding uranium(iv) hydrochalcogenido complexes [((Ad,MeArO)3tacn)U(EH)] (2). Subsequent deprotonation of the terminal hydrochalcogenido species with KN(SiMe3)2, in the presence of 2.2.2-cryptand, gives access to the uranium(iv) complexes with terminal chalcogenido ligands [K(2.2.2-crypt)][((Ad,MeArO)3tacn)U≡E] (3). In order to study the influence of the varying terminal chalogenido ligands on the overall molecular and electronic structure, all complexes were studied by single-crystal X-ray diffractometry, UV/vis/NIR, electronic absorption, and IR vibrational spectroscopy as well as SQUID magnetometry and computational analyses (DFT, MO, NBO).
CRIS-Team Scopus Importer:2019-08-06

A Consecutive Diels-Alder Approach toward a Tet Repressor Directed Combinatorial Library - Gmeiner, Peter; Heinemann, Frank Wilhelm; et al. (Tetrahedron, 2006)
A combinatorial library of 180 tetracycline analogs was generated by solution phase parallel synthesis applying a consecutive Diels-Alder strategy. Chemical methodology suitable for three-dimensional solution phase parallel synthesis was developed that enabled us to generate a collection of potential TetR inducers. The synthesis was built on cross-conjugated trienes as central building blocks facilitating two consecutive cycloaddition processes with different dienophiles. Upon sequential exposure to naphthoquinone and maleimide derivatives, the generation of a carbocyclic skeleton of type 2 incorporating the diversity elements R1-R5 was envisaged. © 2006 Elsevier Ltd. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2006.nat.dchph.lphch.aconse
Keywords: Diels-Alder; Solution phase parallel synthesis; TetR; Tetracycline

A Convenient Way to Novel FeIV Complexes with Mixed N/S/P Coordination Spheres and "Innocent" Ligands - Heinemann, Frank Wilhelm; et al. (Angewandte Chemie (International Edition in English), 1997)
Keywords: N ligands; S ligands; Moessbauer spectroscopy; Iron

A copper(II) thiolate from reductive cleavage of an S-nitrosothiol - Melzer, Marie M.; Mossin, Susanne; Cardenas, Allan Jay P.; Williams, Kamille D.; Zhang, Shiyu; Meyer, Karsten; Warren, Timothy H. (Inorganic Chemistry, 2012)
S-Nitrosothiols RSNO represent circulating reservoirs of nitric oxide activity in the plasma and play intricate roles in protein function control in health and disease. While nitric oxide has been shown to reductively nitrosylate copper(II) centers to form copper(I) complexes and ENO species (E = R N, RO), well-characterized examples of the reverse reaction are rare. Employing the copper(I) β-diketiminate [MeNN]Cu, we illustrate a clear example in which an RS-NO bond is cleaved to release NO with formation of a discrete copper(II) thiolate. The addition of PhCSNO to [MeNN]Cu generates the three-coordinate copper(II) thiolate [MeNN]CuSCPh, which is unstable toward free NO. © 2012 American Chemical Society.

Acriflavine-Functionalized Silica@Manganese Ferrite Nanostructures for Synergistic Radiation and Hypoxia Therapies - Eckenberger, Elisabeth; Raczka, Theodor; Neuhuber, Winfried; Distel, Luitpold; Klein, Stefanie (ACS Applied Bio Materials, 2023)
Mesoporous and nonmesoporous SiO2@MnFe2O4 nanostructures were loaded with the hypoxia-inducible factor-1 inhibitor acriflavine for combined radiation and hypoxia therapies. The X-ray irradiation of the drug-loaded nanostructures not only triggered the release of the acriflavine inside the cells but also initiated an energy transfer from the nanostructures to surface-adsorbed oxygen to generate singlet oxygen. While the drug-loaded mesoporous nanostructures showed an initial drug release before the irradiation, the drug was primarily released upon X-ray radiation in the case of the nonmesoporous nanostructures. However, the drug loading capacity was less efficient for the nonmesoporous nanostructures. Both drug-loaded nanostructures proved to be very efficient in irradiated MCF-7 multicellular tumor spheroids. The damage of these nanostructures toward the nontumorigenic MCF-10A multicellular spheroids was very limited because of the small number of nanostructures that entered the MCF-10A spheroids, while similar concentrations of acriflavine without nanostructures were toxic for the MCF-10A spheroids.
CRIS-Team Scopus Importer:2023-09-29
Keywords: drug delivery; hypoxia; magnetic mesoporous silica@MnFe2O4 nanoparticles; magnetic silica@MnFe2O4 nanoparticle acriflavine; multicellular tumor spheroids; radiation therapy

A Crystalline Iron Terminal Methylidene - Aghazada, Sadig; Munz, Dominik; Heinemann, Frank Wilhelm; Scheurer, Andreas; Meyer, Karsten (Journal of the American Chemical Society, 2021)
Iron methylidene species are alleged intermediates in the Fischer-Tropsch process and in olefin cyclopropanation, yet iron methylidene complexes with unambiguously established molecular and electronic structures remain elusive. In this study, we characterize an iron terminal methylidene complex by single-crystal X-ray diffractometry (scXRD), CHN combustion elemental analysis, 1H/13C/31P/1H-13C NMR, and zero-field 57Fe Mössbauer spectroscopy and study its reactivity. A series of closely related complexes in different oxidation states were synthesized, isolated and characterized in order to validate the electronic structure of the title methylidene complex. The computational analysis substantiates the proposed Fischer-type electronic description while emphasizing high Fe=CH2 bond covalency, considerable double bond order, and thus, substantial alkylidene character.
CRIS-Team Scopus Importer:2021-10-29

Activation and desoxygenation of CO, CO2, and SO2 with sulfur-rich azide and amide. - Sellmann, Dieter; Geipel, Franz; Heinemann, Frank Wilhelm (Chemistry - A European Journal, 2000)
The azide and amide complexes (NBu4)[Ni(N3)('S3')] (2) and (NBu4)[Ni[N(SiMe3)2]('S3')] (4) were found to react with CO, CO2, and SO2 under very mild conditions at temperatures down to -50 degrees C. Depending on the N oxidation state of the nitrogen ligands, addition or partial to complete desoxygenation of the oxides takes place. The reaction between 2 and CO gives (NBU4)[Ni(NCO)('S3')] (3). The reactions between 4 and CO, CO2, and SO2 afford selectively the cyano, isocyanato, and sulfinylimido complexes (NBu4)[Ni(X)('S3')] with X = CN- (5), NCO- (3), and NSO- (6). The silyl groups act as oxygen acceptors. Mechanisms are suggested which have in common the formation of reactive five-coordinate (NBu4)[Ni(L)(L')('S3')] intermediates. In these reactions, highly activated L and L' react with each other. The complexes were characterized by standard methods, and (NBu4)[Ni(CN)('S3')] (5) was also analyzed by X-ray crystallography.

Activation of elemental S, Se and Te with uranium(iii): Bridging U-E-U (E = S, Se) and diamond-core complexes U-(E) 2-U (E = O, S, Se, Te) - Lam, Oanh P.; Heinemann, Frank Wilhelm; Meyer, Karsten (Chemical Science, 2011)
Trivalent uranium complexes supported by tris(aryloxide) chelating ligands, [(( ArO) tacn)U] and [(( ArO) N)U], undergo activation of sulfur and selenium in their elemental forms, generating the mid-valent U(iv)/(U(iv) complexes of the type [(( ArO) tacn)U (μ-E)] and [(( ArO) N)U (μ-E)] (E = S, Se). Under reducing conditions, [(( ArO) N)U] reacts with elemental sulfur, selenium and tellurium to yield the mid-valent dinuclear bis-μ-chalcogenide complexes [Na(DME) ] [(( ArO) N)U (μ-E) ] (E = S, Se, Te) with the diamond-core structural motif and rare inorganic chalcogenide bridging ligands. For comparison, a unique high-valent U(v)/U(v) dinuclear complex [(( ArO) N)U (μ-O) ] was also synthesized. A short uranium-uranium distance in this complex with a U(μ-O) U diamond-core may account for the unusual temperature-dependent magnetic behavior. © The Royal Society of Chemistry 2011.

Activation of H2 and CO by sulfur-rich nickel model complexes for [NiFe] hydrogenases and CO dehydrogenases - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2004)
Keywords: H2 activation; N ligands; Hydrogenases; S ligands; Nickel

Activation of H2 at ruthenium-sulfur cores. - Gottschalk-Gaudig, Torsten; Sellmann, Dieter; Heinemann, Frank Wilhelm (ACS National Meeting Book of Abstracts, 1998)

Activation of Small Molecules by Molecular Uranium Complexes - la Pierre, Henry Storms; Meyer, Karsten (Progress in Inorganic Chemistry, 2014)
This chapter reviews the reaction chemistry of uranium complexes with small molecules of industrial and biological importance. Specifically, carbon monoxide (CO), nitrogen monoxide (NO), dinitrogen (N2), dioxygen (O2), carbon dioxide (CO2), nitrous oxide (N2O), dihydrogen (H2), saturated hydrocarbons, unsaturated hydrocarbons (alkenes, alkynes, and arenes), and water (H2O) are covered. This chapter is limited to molecular systems, and, where appropriate, comparisons with lanthanide or transition metal systems will be made, but are by no means exhaustive. Small-molecule activation studies with uranium do allow for the correlation of molecular-electronic structure/reactivity relationships. These fundamental studies may provide the design criteria for valuable chemical processes and for the development of nuclear waste remediation technologies.
CRIS-Team Scopus Importer:2020-09-14
Keywords: Alkenes; Alkynes; Arenes; Carbon dioxide; Carbon monoxide; Molecular uranium complexes; Nitrogen monoxide; Saturated hydrocarbons; Small-molecule activation

Activation of SO2 and CO2 by trivalent uranium leading to sulfite/dithionite and carbonate/oxalate complexes. - Schmidt, Anna-Corina; Heinemann, Frank Wilhelm; Kefalidis, Christos E.; Maron, Laurent; Roesky, Peter W.; Meyer, Karsten (Chemistry - A European Journal, 2014)
The first sulfite [(((nP,Me) ArO)3 tacn)U(IV) 2 (μ-κ(1) :κ(2) -SO3 )] (tacn=triazacyclononane) and dithionite [(((nP,Me) ArO)3 tacn)U(IV) 2 (μ-κ(2) :κ(2) -S2 O4 )] complexes of uranium from reaction with gaseous SO2 have been prepared. Additionally, the reductive activation of CO2 was investigated with respect to the rare oxalate [(((nP,Me) ArO)3 tacn)U(IV) 2 (μ-κ(2) :κ(2) -C2 O4 )] formation. This ultimately provides the unique S2 O4 (2-) /C2 O4 (2-) and SO3 (2-) /CO3 (2-) complex pairs. All new complexes were characterized by a combination of single-crystal X-ray diffraction, elemental analysis, UV/Vis/NIR electronic absorption, IR vibrational, and (1) H NMR spectroscopy, as well as magnetization (VT SQUID) studies. Moreover, density functional theory (DFT) calculations were carried out to gain further insight into the reaction mechanisms. All observations, together with DFT, support the assumption that SO2 and CO2 show similar (dithionite/oxalate) to analogous (sulfite/carbonate) activation behavior with uranium complexes.

Activation of SO2 with [(η5-C5Me5)2Ln(THF)2] (Ln=Eu, Yb) leading to dithionite and sulfinate complexes - Klementyeva, Svetlana V.; Gamer, Michael T.; Schmidt, Anna-Corina; Meyer, Karsten; Konchenko, Sergey N.; Roesky, Peter W. (Chemistry - A European Journal, 2014)
The reaction of decamethylytterbocene [(η5-C5Me5)2Yb(THF)2] with SO2 at low temperature gave two new compounds, namely, the YbIII dithionite/sulfinate complex [(η5-C5Me5)2Yb(μ3,1κ2O1,3,2κ3O2,2′,4-S2O4)2(η5-C5Me5)Yb(μ,1κO,2κO′-C5Me5SO2)2] (1) and the YbIII dithionite complex [(η5-C5Me5)2Yb2(μ,1κ2O1,3,2κ2O2,4-S2O4)] (2). After extraction of 1, the mixture was heated to give the dinuclear tetrasulfinate complex [(η5-C5Me5)Yb2(μ,κO,κO'-C5Me5SO2)4] (3 a). In contrast, from the reaction of [(η5-C5Me5)2Eu(THF)2] with SO2 only the tetrasulfinate complex [(η5-C5Me5)Eu2(μ,κO,κO'-C5Me5SO2)4] (3 b) was isolated. Two major reaction pathways were observed: 1) reductive coupling of two SO2 molecules to form the dithionite anion S2O42-; and 2) nucleophilic attack of one metallocene C5Me5 ligand on the sulfur atom of SO2. The compounds presented are the first dithionite and sulfinate complexes of the f-elements.
CRIS-Team Scopus Importer:2020-09-14
Keywords: dithionite complexes; lanthanides; rare earths; reduction; SO

Activation of the tertiary carboxamide C-N bond in werner complexes: A classical structure-function relationship - Heinemann, Frank Wilhelm; et al. (Angewandte Chemie International Edition, 2002)
Keywords: Isomerization; Amides; Cleavage reactions; Cadmium; Copper; Coordination chemistry

A cyclometalated diplatinum complex containing 1,1 '-bis(diphenylphosphino)ferrocene as spacer ligand: Antitumor study - Samouei, Hamidreza; Rashidi, Mehdi; Heinemann, Frank Wilhelm (Journal of Organometallic Chemistry, 2011)
Cyclometalated platinum(II) complex [Pt(C boolean AND N)Cl(dmso)], 1, in which C boolean AND N = N(1),C(2')-chelated deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, was reacted with 1 equiv of 1,1'-bis(diphenylphosphino) ferrocene, dppf, to give the cyclometalated diplatinum(II) complex [Pt-2(C boolean AND N)(2)Cl-2(mu-dppf)], 2, along with 0.5 equiv of unreacted dppf. However, the related reaction with 0.5 equiv of dppf produced complex 2 in pure form. Complex 2 in solution was fully characterized by using multinuclear NMR spectroscopy (H-1, C-13, P-31, and Pt-195) and a number of 2D NMR experiments. The structure of complex 2 in solid state was determined by X-ray crystallography showing that the bridging dppf ligand is arranged close to "antiperiplanar staggered" conformation. Cytotoxicity of the complex 2 was studied in three human cancer cell lines derived from ovarian carcinoma(CH1), lung carcinoma(A549), and colon carcinoma (SW480) by means of the MTT assay (MTT = 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide). (C) 2011 Elsevier B.V. All rights reserved.
Keywords: Organoplatinum; Cyclometalation; Phosphine ligand; Antitumor agent; NMR

A diastereoselective route to [(η6-benzyi alcohol)(COD)Ru] complexes - Heinemann, Frank Wilhelm; et al. (Chemische Berichte, 1997)
Keywords: Arene complexes; Reduction; Diastereoselective; Ruthenium

A dimeric gold(I) triphospholyl complex - Zenneck, Ulrich; Hofmann, M.; Heinemann, Frank Wilhelm (Journal of Organometallic Chemistry, 2002)
The reaction of 1-trimethylstannyl-3,5-di(tert-butyl)-1,2,4-triphosphol with PPh3AuCl affords [(1,2,4-triphospholyl)Au(PPh3)] (5) in high yield. NMR spectra of 5 are indicative for a highly dynamic compound in solution. The molecular structure of 5 in the solid state is that of the dimer [(1,2,4-triphospholyl)Au(PPh3)]2. Its most striking feature is a remarkable range of different metal-triphospholyl ligand bonds which create a pronounced asymmetric core of the molecule. The central Au-Au distance of 3.14 Å indicates a weak interaction of the metal atoms. © 2002 Elsevier Science B.V. All rights reserved.
UnivIS-Import:2017-11-07:Pub.2002.nat.dchph.paoc22.adimer
Keywords: Gold; Ligand; NMR spectra; Triphospholyl

A Dinuclear Iron Complex with Two Cofacial [FeS_4_] Cores Linked by Covalent Ligand Periphery Clamps and Dissociable Thiolate Bridges - Sellmann, Dieter; Peters, Kai; Monton, Molina Raquel; Heinemann, Frank Wilhelm (European Journal of Inorganic Chemistry, 2003)
UnivIS-Import:2017-03-24:Pub.2003.forsch.sonder.sfb583.adinuc

Advanced PGSS process for the encapsulation of the biopesticide Cydia pomonella granulovirus - Scheurer, Andreas; et al. (Journal of Supercritical Fluids, 2010)
Keywords: Cydia pomonella granulovirus (CpGV); Biotechnological plant protection agent; Virus-loaded microcapsules; Particles from Gas Saturated Solutions (PGSS)

Advanced Photocatalysts: Pinning Single Atom Co-Catalysts on Titania Nanotubes - Zhou, Xin; Hwang, Imgon; Tomanec, Ondrej; Fehn, Dominik; Mazare, Anca Valentina; Zboril, Radek; Meyer, Karsten; Schmuki, Patrik (Advanced Functional Materials, 2021)
Single atom (SA) catalysis, over the last 10 years, has become a forefront in heterogeneous catalysis, electrocatalysis, and most recently also in photocatalysis. Most crucial when engineering a SA catalyst/support system is the creation of defined anchoring points on the support surface to stabilize reactive SA sites. Here, a so far unexplored but evidently very effective approach to trap and stabilize SAs on a broadly used photocatalyst platform is introduced. In self-organized anodic TiO2 nanotubes, a high degree of stress is incorporated in the amorphous oxide during nanotube growth. During crystallization (by thermal annealing), this leads to a high density of Ti3+-Ov surface defects that are hardly present in other common titania nanostructures (as nanoparticles). These defects are highly effective for SA iridium trapping. Thus a SA-Ir photocatalyst with a higher photocatalytic activity than for any classic co-catalyst arrangement on the semiconductive substrate is obtained. Hence, a tool for SA trapping on titania-based back-contacted platforms is provided for wide application in electrochemistry and photoelectrochemistry. Moreover, it is shown that stably trapped SAs provide virtually all photocatalytic reactivity, with turnover frequencies in the order of 4 × 106 h−1 in spite of representing only a small fraction of the initially loaded SAs.
CRIS-Team Scopus Importer:2021-06-04
Keywords: dark deposition; hydrogen generation; photocatalysis; single atom iridium; single-atom catalysis; TiO

AEI 56-Synthesis, reactivity and electronic structure of sterically pressured uranium complexes - Bart, Suzanne C.; Heinemann, Frank Wilhelm; Meyer, Karsten (ACS National Meeting Book of Abstracts, 2007)

A Ferrocene-Based Dicationic Iron(IV) Carbonyl Complex - Malischewski, Moritz; Seppelt, Konrad; Sutter, Jörg; Munz, Dominik; Meyer, Karsten (Angewandte Chemie International Edition, 2018)
Keywords: carbonyl ligands; cyclopentadienyl ligands; 57Fe Mössbauer spectroscopy; iron; metallocenes

A Fluorescence-Detected Coordination-Induced Spin State Switch - Kurz, Hannah; Schoetz, Konstantin; Papadopoulos, Ilias; Heinemann, Frank Wilhelm; Maid, Harald; Guldi, Dirk Michael; Koehler, Anna; Hoerner, Gerald; Weber, Birgit (Journal of the American Chemical Society, 2021)
The response of the spin state to in situ variation of the coordination number (CISSS) is a promising and viable approach to smart sensor materials, yet it suffers to date from insensitive detection. Herein, we present the synthetic access to a family of planar nickel(II) complexes, whose CISSS is sensitively followed by means of fluorescence detection. For this purpose, nickel(II) complexes with four phenazine-based Schiff base-like ligands were synthesized and characterized through solution-phase spectroscopy (NMR and UV-vis), solid-state structure analysis (single-crystal XRD), and extended theoretical modeling. All of them reveal CISSS in solution through axial ligating a range of N- and O-donors. CISSS correlates nicely with the basicity of the axial ligand and the substitution-dependent acidity of the nickel(II) coordination site. Remarkably, three out of the four nickel(II) complexes are fluorescent in noncoordinating solvents but are fluorescence-silent in the presence of axial ligands such as pyridine. As these complexes are rare examples of fluorescent nickel(II) complexes, the photophysical properties with a coordination number of 4 were studied in detail, including temperature-dependent lifetime and quantum yield determinations. Most importantly, fluorescence quenching upon adding axial ligands allows a "black or white", i.e. digital, sensoring of spin state alternation. Our studies of fluorescence-detected CISSS (FD-CISSS) revealed that absorption-based CISSS and FD-CISSS are super proportional with respect to the pyridine concentration: FD-CISSS features a higher sensitivity. Overall, our findings indicate a favored ligation of these nickel(II) complexes in the excited state in comparison to the ground state.
CRIS-Team WoS Importer:2021-03-26

A Genuine Trivalent Bis-Acylphosphide (BAP) Complex of Uranium - Hochholzer, Jakob; Waldschmidt, Pablo; Heinemann, Frank Wilhelm; Grützmacher, Hansjörg; Meyer, Karsten (European Journal of Inorganic Chemistry, 2024)
The genuine trivalent uranium complex, K[UIII(mesBAP)4], employing four bidentate bis(2,4,6-trimethylbenzoyl)phosphide (mesBAP) chelating ligands, is reported and obtained by the reduction of the literature-known tetravalent analog [UIV(mesBAP)4]. Hence, the bis(acyl)phosphide mesBAP ligand allowed to establish a fully reversible redox couple with uranium in the oxidation states +III and +IV. In both complexes [U(mesBAP)4]0/−, the uranium ions are coordinated to four mesBAP ligands in a square antiprismatic geometry. All new compounds have been characterized by single-crystal XRD analysis, 1H and 31P NMR, and UV/Vis/NIR electronic absorption spectroscopy, as well as SQUID magnetization and electrochemical measurements, and CW X-band EPR in the case of the trivalent complex.
CRIS-Team Scopus Importer:2024-04-26
Keywords: Bisacylphosphide BAP; Ligands; Magnetism; Spectroscopy; Uranium Complexes

Air bubble promoted large scale synthesis of luminescent ZnO nanoparticles - Wintzheimer, Susanne; Spaeth, S.; Shmeliov, A.; Nicolosi, Valeria; Mandel, Karl (Journal of Materials Chemistry C, 2015)
Luminescent zinc oxide nanoparticles were synthesized via a facile one-pot sol-gel synthesis route using zinc acetate dihydrate and potassium hydroxide as cheap precursors. It is demonstrated that dissolved oxygen plays a key role in the synthesis of nanoparticles. For larger scale synthesis batches, it is therefore crucial to provide sufficient oxygen supply during reaction, as otherwise, the formation of ZnO nanoparticles does not occur. A concept is presented to achieve a large gas to liquid interface by introducing air bubbles into the reaction system to ultimately promote ZnO nanoparticle formation at larger scale batches. The flow rate of air during synthesis directly influences the yield and the luminescence intensity of the nanoparticles.
CRIS-Team Scopus Importer:2020-04-02

A large electrochemical setup for the anodization of aluminum towards highly ordered arrays of cylindrical nanopores - Assaud, Loic; Bochmann, Sebastian; Christiansen, Silke; Bachmann, Julien (Review of Scientific Instruments, 2015)
A new electrochemical setup and the associated procedures for growing ordered anodic aluminum oxide pore arrays on large surfaces are presented. The typical size of the samples is 14 x 14 cm(2). The most crucial experimental parameters that allow for the stabilization of the high-field procedures are a very efficient cooling of sample and electrolyte, as well as the initial ramping up of the voltage at an accurately defined rate. The morphology of the cylindrical, parallel alumina pores is similar to those obtained on smaller scales with standard setups. Our setup facilitates the availability of porous anodic alumina as a template system for a number of applications. (C) 2015 AIP Publishing LLC.

A lead(II) toluene complex - Messelberger, Julian; Pinter, Piermaria; Heinemann, Frank Wilhelm; Munz, Dominik (Mendeleev Communications, 2021)
A well defined intermolecular toluene complex of lead(ii) supported by a pincer-type saNHC (saturated N-heterocyclic carbene) ligand was prepared through deprotonation of the bis(irnidazolinium) salt with Pb[N(SiMe3)(2)](2) or metalation of the free carbene and subsequent salt metathesis with Tl(OTf), followed by crystallization from toluene. Combined computational and experimental results indicate that noncovalent interactions with the lead atom (sigma-hole type interaction, dispersion) and the diisopropylphenyl side groups of the ligand (dispersion) stabilize the complex.
CRIS-Team WoS Importer:2021-09-03

Allenylidene complexes based on pentacenequinone - Strinitz, Frank; Waterloo, Andreas; Tucher, Johannes; Huebner, Eike; Tykwinski, Rik; Burzlaff, Nicolai (European Journal of Inorganic Chemistry, 2013)
Stable ruthenium-allenylidene complexes based on pentacenequinone have been synthesized. The complexes show an electronic absorption in the NIR region that arises from forbidden MLCT transitions, as explained by DFT calculations. The crystal structure reveals promising features for the formation of metal-influenced organic FETs. Stable ruthenium-allenylidene complexes based on pentacenequinone have been synthesized. The depicted complex shows an electronic absorption in the NIR region that arises from forbidden MLCT transitions, as explained by DFT calculations. The crystal structure reveals promising features for the formation of metal-influenced organic FETs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Low-Valent Iron Imido Heterocubane Cluster: Reversible Electron Transfer and Catalysis of Selective C-C Couplings - Lichtenberg, Crispin; Garcia Rubio, Ines; Viciu, Liliana; Adelhardt, Mario; Meyer, Karsten; Jeschke, Gunnar; Gruetzmacher, Hansjoerg (Angewandte Chemie International Edition, 2015)
Enzymes and cofactors with iron-sulfur heterocubane core structures, [Fe4S4], are often found in nature as electron transfer reagents in fundamental catalytic transformations. An artificial heterocubane with a [Fe4N4] core is reported that can reversibly store up to four electrons at very negative potentials. The neutral [Fe4N4] and the singly reduced low-valent [Fe4N4]- heterocubanes were isolated and fully characterized. The low-valent species bears one unpaired electron, which is localized predominantly at one iron center in the electronic ground state but fluctuates with increasing temperatures. The electrons stored or released by the [Fe4N4]/[Fe4N4]- redox couple can be used in reductive or oxidative C-C couplings and even allow catalytic one-pot reactions, which show a remarkably enhanced selectivity in the presence of the [Fe4N4] heterocubanes.
CRIS-Team Scopus Importer:2020-09-14
Keywords: C-C coupling; cluster compounds; heterocubanes; homogeneous catalysis; low-valent iron

Alteration of the Optoelectronic Properties of CuInS2 Quantum Dots via Colloidal Annealing - Dehm, Katharina; Zanetti, Alberto; Fett, Bastian; Mauritz, Vincent; Hamburger, Robert C.; Langford, Daniel; Guldi, Dirk Michael; Young, Elizabeth R.; Mandel, Karl; Crisp, Ryan (Crystal Growth and Design, 2024)
Colloidal semiconductor quantum dots (QDs) have tunable optoelectronic properties, thereby making them interesting materials for applications involving light-matter interactions. However, crystallographic and surface defects greatly impair their potential performance in devices. Herein, we present a straightforward approach to improve the quality of copper indium disulfide (CuInS2) QDs by adjusting the parameters of the colloidal synthesis. By the introduction of prolonged heating times after the nanocrystal growth has already gone to completion, defect states are partially removed. This “colloidal annealing” for varying time spans (from 5 up to 90 min) with longer annealing times correlating with a decreased ratio of emission from defect states compared to band edge emission, results in enhanced color purity. At shorter annealing times, the defects removed are mainly structural, indicated by the transition from mixed crystal phases to an almost phase-pure material. At longer annealing times, further improvements are linked to surface defect removal. Findings from transient absorption spectroscopy further confirm this trend by revealing a decrease in the intensity of a photoinduced absorption feature associated with sub-band gap states compared to the band edge bleach signal. These findings highlight the applicability of colloidal annealing as a straightforward strategy for direct material optimization during colloidal synthesis.<br

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The trinuclear complex [('S-2')(Ni(PMe3)

Ambiphilicity: A Characteristic Reactivity Principle of Pi-Bound Phosphorus Heterocycles - Clark, Timothy; Toepffer, Christian; Heinemann, Frank Wilhelm; Hennemann, Matthias; Zenneck, Ulrich; et al. (Angewandte Chemie International Edition, 2002)
Bicycles made in crystals: The phosphorus atoms of the: π ligand 1,3-diphosphete turn out to be ambiphilic centers with pronounced intramolecular reactivity. This property results in a temperature-dependent bond formation in [(2,4-di-tBu-1,3-diphosphete)3Mo], which is found to be a topotactic reaction in the single crystal (see scheme). This new reactivity principle can be used to explain a series of complex interligand bond-formation reactions of phosphorus heterocycles.
UnivIS-Import:2015-04-14:Pub.2002.forsch.sonder.sfb583.ambiph
Keywords: DFT calculations; Molybdenum; P ligands; Phosphorus heterocycles; Pi interactions; Solid-state reactions

A Mononuclear and High-Spin Tetrahedral TiIIComplex - Reinholdt, Anders; Pividori, Daniel Maximilian; Laughlin, Alexander L.; Dimucci, Ida M.; MacMillan, Samantha N.; Jafari, Mehrafshan G.; Gau, Michael R.; Carroll, Patrick J.; Krzystek, J.; Ozarowski, Andrew; Telser, Joshua; Lancaster, Kyle M.; et al. (Inorganic Chemistry, 2020)
A high-spin, mononuclear TiII complex, [(TptBu,Me)TiCl] [TptBu,Me- = hydridotris(3-tert-butyl-5-methylpyrazol-1-yl)borate], confined to a tetrahedral ligand-field environment, has been prepared by reduction of the precursor [(TptBu,Me)TiCl2] with KC8. Complex [(TptBu,Me)TiCl] has a 3A2 ground state (assuming C3v symmetry based on structural studies), established via a combination of high-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy, solution and solid-state magnetic studies, Ti K-edge X-ray absorption spectroscopy (XAS), and both density functional theory and ab initio (complete-active-space self-consistent-field, CASSCF) calculations. The formally and physically defined TiII complex readily binds tetrahydrofuran (THF) to form the paramagnetic adduct [(TptBu,Me)TiCl(THF)], which is impervious to N2 binding. However, in the absence of THF, the TiII complex captures N2 to produce the diamagnetic complex [(TptBu,Me)TiCl]2(η1,η1μ2-N2), with a linear TiNNTi topology, established by single-crystal X-ray diffraction. The N2 complex was characterized using XAS as well as IR and Raman spectroscopies, thus establishing this complex to possess two TiIII centers covalently bridged by an N22- unit. A πacid such as CNAd (Ad = 1-adamantyl) coordinates to [(TptBu,Me)TiCl] without inducing spin pairing of the d electrons, thereby forming a unique high-spin and five-coordinate TiII complex, namely, [(TptBu,Me)TiCl(CNAd)]. The reducing power of the coordinatively unsaturated TiII-containing [(ptBu,Me)TiCl] species, quantified by electrochemistry, provides access to a family of mononuclear TiIV complexes of the type [(TptBu,Me)TiE(Cl)] (with E2- = NSiMe3, N2CPh2, O, and NH) by virtue of atom- or group-transfer reactions using various small molecules such as N3SiMe3, N2CPh2, N2O, and the bicyclic amine 2,3:5,6-dibenzo-7-azabicyclo[2.2.1]hepta-2,5-diene.
CRIS-Team Scopus Importer:2020-12-25

A mononuclear Fe(III) single molecule magnet with a 3/2↔5/2 spin crossover - Mossin, Susanne; Tran, Ba L.; Adhikari, Debashis; Pink, Maren; Heinemann, Frank Wilhelm; Sutter, Jörg; Szilagyi, Robert K.; Meyer, Karsten; Mindiola, Daniel J. (Journal of the American Chemical Society, 2012)
The air stable complex [(PNP)FeCl2] (1) (PNP = N[2-P(CHMe2)(2)-4-methylphenyl](2)(-)), prepared from one-electron oxidation of [(PNP)FeCl] with ClCPh3, displays an unexpected S = 3/2 to S = 5/2 transition above 80 K as inferred by the dc SQUID magnetic susceptibility measurement The ac SQUID magnetization data, at zero field and between frequencies 10 and 1042 Hz, dearly reveal complex 1 to have frequency dependence on the out-of-phase signal and thus being a single molecular magnet with a thermally activated barrier of U-eff = 32-36 cm(-1) (47-52 K). Variable-temperature Mossbauer data also corroborate a significant temperature dependence in delta and Delta E-Q values for 1, which is in agreement with the system undergoing a change in spin state. Likewise, variable temperature X-band EPR spectra of 1 reveals the S = 3/2 to be likely the ground state with the S = 5/2 being close in energy. Multiedge XAS absorption spectra suggest the electronic structure of 1 to be highly covalent with an effective iron oxidation state that is more reduced than the typical ferric complexes due to the significant interaction of the phosphine groups in PNP and Cl ligands with iron. A variable temperature single crystal X-ray diffraction study of 1 collected between 30 and 300 K also reveals elongation of the Fe-P bond lengths and increment in the Cl-Fe-Cl angle as the S = 5/2 state is populated Theoretical studies show overall similar orbital pictures except for the d(z(2)) orbital, which has the most sensitivity to change in the geometry and bonding, where the quartet (B-4) and the sextet ((6)A) states are close in energy.

An additive-free silicon anode in nanotube morphology as a model lithium ion battery material - Zhuo, Ying; Sun, Hong; Uddin, Md. Helal; Barr, Maissa; Wisser, Dorothea; Roßmann, Philip Kazys; Esper, Julian Duane; Tymek, Sarah; Döhler, Dirk; Peukert, Wolfgang; Hartmann, Martin; Bachmann, Julien (Electrochimica Acta, 2021)
Ordered arrays of parallel, cylindrical silicon nanotubes are obtained by aluminothermic reduction of SiO2 nanotubes generated by atomic layer deposition (ALD) on nanoporous aluminum oxide templates. The reduction to amorphous Si (a-Si) is characterized by a combination of X-ray diffraction (XRD), solid-state cross-polarization magic-angle spinning nuclear magnetic resonance (29Si CP-MAS NMR), ultraviolet-visible spectroscopy, attenuated total reflectance infrared spectroscopy (ATR-IR), and X-ray photoelectron spectroscopy (XPS). These a-Si nanotube arrays are electrochemically active in a lithium-ion battery environment when prepared on Cu current collectors without any additives. The absence of the traditional additive carbon black, which is an electrochemically inert conductor, increases the proportion of capacity associated with faradaic reactions (Li incorporation) with respect to the capacitive component. Electrochemical impedance spectroscopy (EIS) and charge-discharge tests demonstrate that the nanotube morphology yields an improved tolerance to fast cycling.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Aluminothermic reduction; Anode material; Atomic layer deposition; Lithium ion battery; Si nanotube

An Air-Stable Heterobimetallic Si2M2 Tetrahedral Cluster - Dübek, Gizem; Hanusch, Franziska; Munz, Dominik; Inoue, Shigeyoshi (Angewandte Chemie International Edition, 2020)
Air- and moisture-stable heterobimetallic tetrahedral clusters [Cp(CO)2MSiR]2 (M=Mo or W; R=SitBu3) were isolated from the reaction of N-heterocyclic carbene (NHC) stabilized silyl(silylidene) metal complexes Cp(CO)2M=Si(SitBu3)NHC with a mild Lewis acid (BPh3). Alternatively, treatment of the NHC-stabilized silylidene complex Cp(CO)2W=Si(SitBu3)NHC with stronger Lewis acids such as AlCl3 or B(C6F5)3 resulted in the reversible coordination of the Lewis acid to one of the carbonyl ligands. Computational investigations revealed that the dimerization of the intermediate metal silylidyne (M≡Si) complex to a tetrahedral cluster instead of a planar four-membered ring is due to steric bulk.
CRIS-Team Scopus Importer:2020-03-06
Keywords: cluster compounds; silicon; silylidenes; silylidynes; tetrahedranes

An all white magnet by combination of electronic properties of a white light emitting MOF with strong magnetic particle systems - Seuffert, Marcel T.; Wintzheimer, Susanne; Oppmann, Maximilian; Granath, Tim; Prieschl, Johannes; Alrefai, Anas; Holdt, Hans Jürgen; Müller-Buschbaum, Klaus; Mandel, Karl (Journal of Materials Chemistry C, 2020)
A multi-component particle system was developed that combines the properties of white color, white light emission and strong magnetism on the macroscopic and microscopic scale. The system is constituted by combination of an inorganic white core with either hard or soft magnetic properties and a white light emitting MOF. The key towards this achievement is the supraparticulate character constituted by a magnetic core, of either magnetite or α-Fe, surrounded by titania and silica nanoparticles of a certain size in a loose structural shell-arrangement as white components and finally the white light emitting metal-organic framework (MOF) EuTb@IFP-1 as building blocks of a core-shell structure. The supraparticles are created by forced assembly of the inorganic compounds and by combining spray-drying and postsynthetic modification by solvothermal chemistry. Thereby, the gap is bridged that homogenous compounds are either strongly magnetic, white in appearance or white light emitting. The composites presented herein inherit these properties intrinsically as electronic properties. The white characteristics are based on all optical properties that enable white: light reflection, refraction, and light emission. This work shifts the paradigm that strong magnetic materials are always expected to be intrinsically dark. This journal is
CRIS-Team Scopus Importer:2020-12-11

Analysis of the influence of synthetic paramaters on the structure and physico-chemical properties of non-spherical iron oxide nanocrystals and their biological stability and compatibility - Pujales Paradela, Rosa; et al. (Dalton Transactions, 2016)
In this work, we analyzed the effects of subtle changes in the synthetic conditions and synthetic parameters on the resulting size, shape, monodispersity, crystallinity and magnetic properties of iron oxide nanocrystals (IONCs) obtained through a modified one pot method for the production of mainly cubicshaped nanoparticles (NPs). Cubic, octahedral and cuboctahedral shapes with different sizes and monodispersity could be obtained by slightly changing the stabilizer/precursor molar ratio, the precursor concentration, the reaction time and temperature and/or the heating rate. Their physical properties were evaluated using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), selected-area electron diffraction (SAED) and a superconducting quantum interference (SQUID) device. It was found that monodisperse cubic nanocrystals from ca. 25 to 94 nm could be obtained either by changing the precursor concentration, the heating rate or the reaction time. These cubic nanocrystals were ferrimagnetic in the whole temperature rage analyzed, with saturation magnetization values even larger than those of bulk magnetite. In addition, slightly truncated octahedral NPs could be achieved at relatively large heating ramp rates, whereas cubooctahedral NPs were derived by simply increasing the stabilizer/precursor molar ratio. The saturation magnetization of both types of NPs was slightly lower than the cubic ones, but they were still ferrimagnetic in the whole temperature range analyzed. Moreover, transfer to aqueous solution was possible by a ligand exchange with dimercaptosuccinic acid (DMSA) providing, at the same time, chemical groups for additional functionalization if required. The DMSA-coated cubic IONCs were fairly stable in culture medium, allowing their internalization by different cell types. The NPs inside the cells were located in the cytoplasm and most of them showed a perinuclear distribution. Moreover, a great cytocompatibility in a large range of particle concentrations was observed without the induction of morphological changes in the cultured cells.

An Approach to Rigid, Optically Active Chelate Ligands with C-2 Symmetry: Dialkylhexaphosphapentaprismanes - Höhn, Christine; Keller, Irene; Rohwer, Lars; Heinemann, Frank Wilhelm; Zenneck, Ulrich (European Journal of Inorganic Chemistry, 2013)
Diastereomeric Pd and Pt complexes with a highly rigid chelate cage ligand core have been designed on the basis of alkylated C-2-symmetric tetra-tert-butylhexaphosphapentaprismanes R(2)P(6)C(4)tBu(4). The ligands are accessible by substitution of the diiodo derivative I(2)P(6)C(4)tBu(4) with Grignard and organyllithium reagents. Depending on the optical properties of the organyl group, racemic or diastereomeric dialkylhexaphosphapentaprismanes R(2)P(6)C(4)tBu(4) can be treated with suitable Pd-II or Pt-II precursor complexes to form neutral square-planar cis-[(R(2)P(6)C(4)tBu(4))PdCl2] and cis-[(R(2)P(6)C(4)tBu(4))PtCl2] complexes, respectively. Monoalkylation products RIP(6)C(4)tBu(4) were also observed in the reaction mixtures, but in most cases were inactive as chelate ligands towards Pd-II and Pt-II. For R = (S)-2-methylbutyl, the diastereomers of the PdCl2 complex were efficiently separated by column chromatography and crystallization to give the two diastereomers in up to >99% de and they were fully characterized by NMR and CD spectroscopy as well as by X-ray diffraction analysis. The two diastereomers of cis-[(S)-2-methylbutyl(2)(P(6)C(4)tBu(4))PdCl2] represent the first example of a pair of isolated optically active, C-2-symmetric, square-planar Pd-II complexes with chelate P-C cage ligands. A square-planar Pd complex with two monoanionic RP(6)C(4)tBu(4) cage ligands can be obtained from the monoallylation product (allyl)IP(6)C(4)tBu(4). This reaction failed for the other monoalkylation products RIP(6)C(4)tBu(4) and Pt-II.
Keywords: Cage compounds; Ligand design; Phosphorus; Chirality; Coordination modes

An Editorial about Elemental Analysis - Gabbai, Francois P.; Chirik, Paul J.; Fogg, Deryn E.; Meyer, Karsten; Mindiola, Daniel J.; Schafer, Laurel L.; You, Shu-Li (Organometallics, 2016)
CRIS-Team Scopus Importer:2020-09-14

An electrically conducting 3D coronene-based metal-organic framework - Schönherr, Marina I.; Scheurle, Patricia I.; Frey, Laura; Martínez-Abadía, Marta; Döblinger, Markus; Mähringer, Andre; Fehn, Dominik; Gerhards, Lena; Santourian, Irina; Schirmacher, Alfred; Quast, Tatjana; Wittstock, Gunther; et al. (Journal of Materials Chemistry A, 2024)
A novel cubic mesoporous metal-organic framework (MOF), consisting of hexahydroxy-cata-hexabenzocoronene (c-HBC) and FeIII ions is presented. The highly crystalline and porous MOF features broad optical absorption over the whole visible and near infrared spectral regions. An electrical conductivity of 10−4 S cm−1 was measured on a pressed pellet.
CRIS-Team Scopus Importer:2024-05-03

An Electrically Conducting Three-Dimensional Iron-Catecholate Porous Framework - Mahringer, Andre; Doeblinger, Markus; Hennemann, Matthias; Gruber, Christoph; Fehn, Dominik; Scheurle, Patricia I.; Hosseini, Pouya; Santourian, Irina; Schirmacher, Alfred; Rotter, Julian M.; Wittstock, Gunther; Meyer, Karsten; et al. (Angewandte Chemie International Edition, 2021)
We report the synthesis of a unique cubic metal-organic framework (MOF), Fe-HHTP-MOF, comprising hexahydroxytriphenylene (HHTP) supertetrahedral units and Fe-III ions, arranged in a diamond topology. The MOF is synthesized under solvothermal conditions, yielding a highly crystalline, deep black powder, with crystallites of 300-500 nm size and tetrahedral morphology. Nitrogen sorption analysis indicates a highly porous material with a surface area exceeding 1400 m(2) g(-1). Furthermore, Fe-HHTP-MOF shows broadband absorption from 475 up to 1900 nm with excellent absorption capability of 98.5 % of the incoming light over the visible spectral region. Electrical conductivity measurements of pressed pellets reveal a high intrinsic electrical conductivity of up to 10(-3) S cm(-1). Quantum mechanical calculations predict Fe-HHTP-MOF to be an efficient electron conductor, exhibiting continuous charge-carrier pathways throughout the structure.
CRIS-Team WoS Importer:2021-07-16

An electrochemically functional layer of hydrogenase extract on an electrode of large and tunable specific surface area - Schlicht, Stefanie; Assaud, Loic; Hansen, Moritz; Licklederer, Markus; Bechelany, Mikhael; Perner, Mirjam; Bachmann, Julien (Journal of Materials Chemistry A, 2016)
Electrode supports are generated by electrospinning of polyacrylonitrile fibers and subsequent coating of a thin electrically conductive TiO2 layer by atomic layer deposition. The supports are then functionalized with a [NiFe]-hydrogenase-containing membrane fraction from Escherichia coli and are characterized structurally and electrochemically. The hydrogenase suspension generates a micron-thick organic film around the fiber mat, which exhibits electrocatalytic activity for hydrogen evolution. Furthermore, the electrode geometric surface area is varied systematically via the electrospinning procedure, which reduces the charge transfer resistance and increases the hydrogen evolution current density to > 500 mu A cm(-2) at 0.3 V overpotential.

An enantiopure N,N,O heteroscorpionate ligand derived from (-)-menthone - Bleifuß, Sascha; Hofmann, Fabian; Burzlaff, Nicolai (Zeitschrift für Anorganische und Allgemeine Chemie, 2013)
A new enantiopure heteroscorpionate ligand HOPhbpm (2) was synthesized in a one-pot synthesis. Ligand 2 was obtained in a pyridine-catalysed Peterson rearrangement starting from menthopyrazole, thionyl chloride, and salicylaldehyde. The evidence of κ-coordination of the ligand was shown by the formation of a tetrahedral zinc complex [Zn-κ-(OPhbpm)CH] (3) as well as an molybdenum complex [Mo-κ-(OPhbpm)O Cl] (4). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An enantiopure N,N,S scorpionate ligand derived from (+)-camphor - Godau, Tom; Platzmann, Florian; Heinemann, Frank Wilhelm; Burzlaff, Nicolai (Dalton Transactions, 2009)
Reductive S-S bond cleavage of a disulfide precursor 3 obtained from a pyridine-catalyzed Peterson-type reaction starting from camphorpyrazole 1, thionyl chloride and 2-methyl-2-(methyldithio)propionaldehyde yields 2,2′-bis(camphorpyrazol-1-yl)-2-methylpropane-2-thiol (HS prbpm, 4); the first zinc complexes bearing this ligand exhibit κ coordination of the ligand. © 2009 The Royal Society of Chemistry.

A Neutral Tetraphosphacyclobutadiene Ligand in Cobalt(I) Complexes - Yao, Shenglai; Lindenmaier, Nils; Xiong, Yun; Inoue, Shigeyoshi; Szilvasi, Tibor; Adelhardt, Mario; Sutter, Jörg; Meyer, Karsten; Driess, Matthias (Angewandte Chemie International Edition, 2015)
The unusual reactivity of the newly synthesized -diketiminato cobalt(I) complexes, [((LCo)-Co-Dep)(2)] (2a, L-Dep=CH[C(Me)N(2,6-Et2C6H3)](2)) and [L(Dipp)Cotoluene] (2b, L-Dipp=CH[CHN(2,6-(Pr2C6H3)-Pr-i)](2)), toward white phosphorus was investigated, affording the first cobalt(I) complexes [((LCo)-Co-Dep)(2)((2):(4),(4)-P-4)] (3a) and [((LCo)-Co-Dipp)(2)((2):(4),(4)-P-4)] (3b) bearing the neutral cyclo-P-4 ligand with a rectangular-planar structure. The redox chemistry of 3a and 3b was studied by cyclic voltammetry and their chemical reduction with one molar equivalent of potassium graphite led to the isolation of [((LCo)-Co-Dep)(2)((2):(4),(4)-P-4)][K(dme)(4)] (4a) and [((LCo)-Co-Dipp)(2)((2):(4),(4)-P-4)][K(dme)(4)] (4b). Unexpectedly, the monoanionic Co2P4 core in 4a and 4b, respectively, contains the two-electron-reduced cyclo-P-4(2-) ligand with a square-planar structure and mixed-valent cobalt(I,II) sites. The electronic structures of 3a, 3b, 4a, and 4b were elucidated by NMR and EPR spectroscopy as well as magnetic measurements and are in agreement with results of broken-symmetry DFT calculations.
Keywords: bond activation; cobalt; -diketiminates; phosphorus

A new bis-pyrazolylpyridine ruthenium(III) complex as a potential anticancer drug: in vitro and in vivo activity in murine colon cancer - Lazic, Dejan; Scheurer, Andreas; Cocic, Dusan; Milovanovic, Jelena; Arsenijevic, Aleksandar; Stojanovic, Bojana; Arsenijevic, Nebojsa; Milovanovic, Marija; Simovic, Ana Rilak (Dalton Transactions, 2021)
We synthesized and characterized the ruthenium(III) pincer-type complex [RuCl3(H2Lt-Bu] (H2Lt-Bu = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine, 1) by elemental analysis, IR and UV-Vis spectroscopy, and the mass spectrometry (MS) method ESI Q-TOF. For comparison reasons, we also studied ruthenium(III) terpyridine complexes of the general formula [Ru(N-N-N)Cl-3], where N-N-N = 4'-chloro-terpyridine (Cl-tpy; 2) or 4'-chlorophenyl-terpyridine (Cl-Ph-tpy; 3). A kinetic study of the substitution reactions of 1-3 with biomolecules showed that the rate constants depend on the properties of the spectator ligand and the nature of the entering nucleophile. The DNA/HSA binding study showed that in comparison to complex 1 (bis-pyrazolylpyridine), the other two (2 and 3) terpyridine complexes had a slightly better binding affinity to calf thymus DNA (CT DNA), while in the case of human serum albumin (HSA), complex 1 exhibited the strongest quenching ability. We demonstrated that 1 possesses significant in vitro cytotoxic activity against mouse colon carcinoma CT26 cells and in vivo antitumor activity in murine heterotopic colon carcinoma. Complex 1 induced G0/G1 cell cycle arrest and apoptotic death in CT26 cells. Additionally, 1 showed anti-proliferative activity, as evaluated by the detection of the expression levels of the Ki67 protein. Furthermore, the in vivo results showed that 1 reduced primary tumour growth and the number and growth of lung and liver metastases, significantly prolonging the treated mice's survival rate. This study highlighted that 1 does not show hepato- and nephrotoxicity. Our data demonstrated the considerable antitumor activity of the ruthenium(iii) pincer complex against CT26 tumour cells and implicated further investigations of its role as a potential chemotherapeutic agent for colon carcinoma.
CRIS-Team WoS Importer:2021-05-28

A new carbonate bridged dinuclear zinc complex with tripodal amine ligands - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 1999)
Keywords: Carbonate complexes; Tripodal amine complexes; Crystal structures; Zinc complexes

A new class of double alkyl-substituted, liquid crystalline imidazolium ionic liquids - A unique combination of structural features, viscosity effects, and thermal properties - Wang, Xinjiao; Heinemann, Frank Wilhelm; Yang, Mei; Melcher, Berthold Ulrich; Fekete, Melinda; Mudring, Anja-Verena; Wasserscheid, Peter; Meyer, Karsten (Chemical Communications, 2009)
1,3-Didodecylimidazolium salts have been prepared as first representatives of a new class of ionic liquid crystals (ILCs), showing thermotropic liquid crystalline behaviour in an extended temperature range below 70 °C. Remarkably strong non-Newtonian viscosity behaviour was found for the liquid-crystalline state of these ILCs. © 2009 The Royal Society of Chemistry.

A New Class of Task-Specific Imidazolium Salts and Ionic Liquids and Their Corresponding Transition-Metal Complexes for Immobilization on Electrochemically Active Surfaces - Seidl, Vera; Romero Cordero, Angel Heriberto; Heinemann, Frank Wilhelm; Scheurer, Andreas; Vogel, Carola; Unruh, Tobias; Wasserscheid, Peter; Meyer, Karsten (Chemistry - A European Journal, 2022)
Adding to the versatile class of ionic liquids, we report the detailed structure and property analysis of a new class of asymmetrically substituted imidazolium salts, offering interesting thermal characteristics, such as liquid crystalline behavior, polymorphism or glass transitions. A scalable general synthetic procedure for N-polyaryl-N’-alkyl-functionalized imidazolium salts with para-substituted linker (L) moieties at the aryl chain, namely [LPhmImHR]+ (L=Br, CN, SMe, CO2Et, OH; m=2, 3; R=C12, PEGn; n=2, 3, 4), was developed. These imidazolium salts were studied by single-crystal X-ray diffraction (SC-XRD), NMR spectroscopy and thermochemical methods (DSC, TGA). Furthermore, these imidazolium salts were used as N-heterocyclic carbene (NHC) ligand precursors for mononuclear, first-row transition metal complexes (MnII, FeII, CoII, NiII, ZnII, CuI, AgI, AuI) and for the dinuclear Ti-supported Fe-NHC complex [(OPy)2Ti(OPh2ImC12)2(FeI2)] (OPy=pyridin-2-ylmethanolate). The complexes were studied concerning their structural and magnetic behavior via multi-nuclear NMR spectroscopy, SC-XRD analyses, variable temperature and field-dependent (VT-VF) SQUID magnetization methods, X-band EPR spectroscopy and, where appropriate, zero-field 57Fe Mössbauer spectroscopy.
CRIS-Team Scopus Importer:2022-03-25
Keywords: carbene ligands; electronic structure; ionic liquids; solid-state structure; thermal properties

A new diamantane functionalized tris(aryloxide) ligand system for small molecule activation chemistry at reactive uranium complexes - Lam, Oanh P.; Heinemann, Frank Wilhelm; Meyer, Karsten (Comptes Rendus Chimie, 2010)
The diamantane functionalized triazacyclononane ligand ( ArOH)tacn (L) has been synthesized and the reactivity of its U(III) metallated product [((ArO) tacn)U] (1) has been explored. Complex 1 promotes dichloromethane and azidotrimethylsilane activation to generate U(IV) complex [(( ArO)tacn)U(Cl)] (2) and U(V) complex [(( ArO)tacn) U(NTMS)] (3), respectively. Spectroscopic investigations of complexes 1, 2, and 3 will be discussed, along with molecular structures where possible. © 2010 Published by Elsevier Masson SAS on behalf of Académie des sciences.

A new high-pressure NMR probe designed for a narrow bore magnet system - van Eldik, Rudi; Weller, Manfred; Zahl, Achim; Igel, Peter (Review of Scientific Instruments, 2004)
UnivIS-Import:2015-03-09:Pub.2004.nat.dchph.laoc1.anewhi

A new sterically loaded pentadentate N3S2 ligand and its zinc complexes - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 2007)
In quest of complexes having [MN3S2] cores in the monomeric form and trans-thiolate donor atoms, the new pentadentate thiolate amine py(t)BuN(2)H(2)S(2-)H(2) [=py(t)BuN(2)H(2)S(2)(2-)=2,6-bis(2-mercapto-3, 5-di-tert-butylphenylaminomethyl)pyridine(2-)] has been synthesized. The template condensation reaction of bis(2-mercapto-3,5-di-tert-butylaniline)zinc (II)[Zn((t)Bu(2)ma)(2)] and pyridine-2,6-dicarbaidehyde in methanol at 40 degrees C leads to the formation of imine zinc complex [Zn(py(t)BuN(2)S(2))] (7), which is very unstable and decomposes to give thiazole 5. However, if the template condensation is followed by in situ reduction with an excess of NaBH4, the stable saturated amine complex [Zn(py(t)BuN(2)H(2)S(2))] (8) is formed. Demetallation of zinc complex 8 under acidic conditions leads to the formation of the desired dithiolate py(t)BuN(2)H(2)S(2)-H-2 ligand (9). (C) 2007 Elsevier B.V. All rights reserved.
Keywords: amine sulfur ligands; nitrogenases; template synthesis; steric ligands

A New Trigonal-Bipyramidal [Cu-II(pytBuN(3))Cl-2] Complex: Synthesis, Structure and Ligand Substitution Behaviour - Shaban, Shaban Abd El Fattah Youssef; Heinemann, Frank Wilhelm; van Eldik, Rudi (European Journal of Inorganic Chemistry, 2009)
The synthesis, structure and ligand substitution mechanism of a new five-coordinate copper(II) complex with a sterically constrained pytBuN(3) chelate ligand [pytBuN(3) = 2,6-bis(3,5di-tert-butylphenyhminomethyl)pyridine] are reported. In the crystal structure of the complex the [Cu(pytBuN(3))Cl-2] chromophore possesses a distorted trigonal-bipyramidal coordination geometry. The kinetics and mechanism of chloride substitution by thiourea (TU) and N,N,N',N'-tetramethylthiourea (TMTU) were studied in detail as a function of nucleophile concentration, temperature and pressure in methanol as solvent. The kinetics showed that the substitution reaction of [Cu(pytBuN(3))Cl-2] is a biphasic process that involves the subsequent displacement of both chloride ligands. The substitution of the first chloride by TU, k(1)(296) = 918 +/- 30 M-1 s(-1), is 570 times faster than the substitution of the second chloride, k(2)(296) = 1.62 +/- 0.06 M-1 s(-1). Substitution of chloride by TU is characterized by the activation parameters: Delta H-# = 42 2 and 58 +/- 2 kJmol(-1), Delta S-# = -46 +/- 7 and -47 +/- 6 J K(-1)mol(-1), and Delta V-# = -6.5 +/- 0.2 and -5.3 +/- 0.7 cm(3)mol(-1), for the first and second substitution reactions, respectively. It is concluded from the activation parameters that both reactions follow an associative interchange (I-a) mechanism. When the substitution reaction was carried out with the sterically hindered nucleophile TMTU, the rate constant for the displacement of the first chloride, k(2)(296) = 6.9 +/- 0.5 M-1 s(-1), was more than 133 times slower than for the reaction with TU, which further supports the I-a nature of the substitution mechanism. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Keywords: Copper; Chelates; Copper(II) complexes; Kinetics; UV/Vis spectroscopy; Biphasic reaction

A new tripodal ligand system with steric and electronic modularity for uranium coordination chemistry - Bart, Suzanne C.; Heinemann, Frank Wilhelm; Anthon, Christian; Hauser, Christina; Meyer, Karsten (Inorganic Chemistry, 2009)
The synthesis of a potentially redox active tripodal ligand containing a tris(aryloxide) functionalized mesitylene anchor, (( ArOH) mes) (1), and its metalation with low-valent uranium to form [(( ArO) mes)U] (1-U) Is reported. The results from characterization by X-ray crystallography, spectroscopic studies, and computational analysis, as well as Initial reactivity studies, support a +3 uranium oxidation state. Comparison to the previously synthesized complex, [(( ArO) tacn)U] (2-U), featuring the redox-lnnocent triazacyclononane anchor reveals that changing the anchor from the flexible trlazacyclononane to a rigid mesityl fragment increases the structural flexibility of the aryloxide substituents in complexes of 1. The synthesis and crystal structures of uranium(IV) amide complexes of 1-U and 2-U are discussed. © 2009 American Chemical Society.

An improved synthesis of 4-cyano-1,10-phenanthroline, 4,7-dicyano-1,10- phenanthroline and their bis(4,4′-di-tert-butyl-2,2′-bipyridine) ruthenium(II) complexes - Staehle, Robert; Menzel, Roberto; Peuntinger, Katrin; Pilz, T. David; Heinemann, Frank Wilhelm; Guldi, Dirk Michael; Beckert, Rainer; Rau, Sven (Polyhedron, 2014)
This report describes a new palladium catalyzed synthesis of 4-cyano-1,10-phenanthroline (nphen, 1), 4,7-dicyano-1,10-phenanthroline (dnphen, 2) and their corresponding ruthenium complexes. The two cationic complexes, [(tbbpy)Ru(nphen)] 3 and [(tbbpy)Ru(dnphen) ] 4 (tbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine), were synthesized using an improved microwave procedure. All compounds were fully characterized, including the solid-state molecular structures of the complexes. The influence of 1 and 2 on the metal-to-ligand charge transfer (MLCT) transitions were studied and compared to the ruthenium(II) polypyridyl complexes containing the related 4,4′-dicyano-2,2′-bipyridine (dnbpy) and the non-functionalized 1,10-phenanthroline (phen) ligand. © 2014 Elsevier Ltd. All rights reserved.

An intermediate cobalt(IV) nitrido complex and its N-migratory insertion product. - Zolnhofer, Eva; Käß, Martina; Khusniyarov, Marat; Heinemann, Frank Wilhelm; Maron, Laurent; Van Gastel, Maurice; Bill, Eckhard; Meyer, Karsten (Journal of the American Chemical Society, 2014)
Low-temperature photolysis experiments (T = 10 K) on the tripodal azido complex [(BIMPN(Mes,Ad,Me))Co(II)(N3)] (1) were monitored by EPR spectroscopy and support the formation of an exceedingly reactive, high-valent Co nitrido species [(BIMPN(Mes,Ad,Me))Co(IV)(N)] (2). Density functional theory calculations suggest a low-spin d(5), S = 1/2, electronic configuration of the central cobalt ion in 2 and, thus, are in line with the formulation of complex 2 as a genuine, low-spin Co(IV) nitride species. Although the reactivity of this species precludes handling above 50 K or isolation in the solid state, the N-migratory insertion product [(NH-BIMPN(Mes,Ad,Me))Co(II)](BPh4) (3) is isolable and was reproducibly synthesized as well as fully characterized, including CHN elemental analysis, paramagnetic (1)H NMR, IR, UV-vis, and EPR spectroscopy as well as SQUID magnetization and single-crystal X-ray crystallography studies. A computational analysis of the reaction pathway 2 → 3 indicates that the reaction readily occurs via N-migratory insertion into the Co-C bond (activation barrier of 2.2 kcal mol(-1)). In addition to the unusual reactivity of the nitride 2, the resulting divalent cobalt complex 3 is a rare example of a trigonal pyramidal complex with four different donor ligands of a tetradentate chelate-an N-heterocyclic carbene, a phenolate, an imine, and an amine-binding to a high-spin Co(II) ion. This renders complex 3 chiral-at-metal.

An Iron-Mesoionic Carbene Complex for Catalytic Intramolecular C-H Amination Utilizing Organic Azides - Stroek, Wowa; Keilwerth, Martin; Pividori, Daniel Maximilian; Meyer, Karsten; Albrecht, Martin (Journal of the American Chemical Society, 2021)
The synthesis of N-heterocycles is of paramount importance for the pharmaceutical industry. They are often synthesized through atom economic and environmentally unfriendly methods, generating significant waste. A less explored, but greener, alternative is the synthesis through the direct intramolecular C-H amination utilizing organic azides. Few examples exist by using this method, but many are limited due to the required use of stoichiometric amounts of Boc2O. Herein, we report a homoleptic C,O-chelating mesoionic carbene-iron complex, which is the first iron-based complex that does not require the addition of any protecting groups for this transformation and that is active also in strong donor solvents such as THF or even DMSO. The achieved turnover number is an order of magnitude higher than any other reported catalytic system. A variety of C-H bonds were activated, including benzylic, primary, secondary, and tertiary. By following the reaction over time, we determined the presence of an initiation period. Kinetic studies showed a first-order dependence on substrate concentration and half-order dependence on catalyst concentration. Intermolecular competition reactions with deuterated substrate showed no KIE, while separate reactions with deuterium-labeled substrate resulted in a KIE of 2.0. Moreover, utilizing deuterated substrate significantly decreased the initiation period of the catalysis. Preliminary mechanistic studies suggest a unique mechanism involving a dimeric iron species as the catalyst resting state.
CRIS-Team Scopus Importer:2021-12-24

An iron nitride complex - Vogel, Carola; Heinemann, Frank Wilhelm; Sutter, Jörg; Anthon, Christian; Meyer, Karsten (Angewandte Chemie International Edition, 2008)

An Iron Pincer Complex in Four Oxidation States - Gravogl, Lisa; Heinemann, Frank Wilhelm; Munz, Dominik; Meyer, Karsten (Inorganic Chemistry, 2020)
The synthesis and characterization of a series of homoleptic iron complexes [Fe(benzNHCOCO)2]2-/1-/0/1+ supported by the tridentate bis-aryloxide benzimidazolin-2-ylidene pincer ligand benzNHCOCO2- (II) is presented. While the reaction of 2 equiv of free ligand II with a ferrous iron precursor leads to the isolation of the coordination polymer [Fe(benzNHCOCOK)2]n (1), treatment of II with ferric iron salts allows for the synthesis and isolation of the mononuclear, octahedral bis-pincer compound K[Fe(benzNHCOCO)2] (2) and its crown-ether derivative [K(18c6)(THF)2][Fe(benzNHCOCO)2] (3). Electrochemical studies of 2 suggested stable products upon further one- and two-electron oxidation. Hence, treatment of 2 with 1 equiv of AgPF6 yields the charge-neutral species [Fe(benzNHCOCO)2] (4). Similarly, the cationic complex [Fe(benzNHCOCO)2]PF6 (5) is obtained by addition of 2 equiv of AgPF6. The characterization of complexes 1, 3, and 4 reveals iron-centered reduction and oxidation processes; thus, preserving the dianionic, closed-shell structure of both coordinated benzNHCOCO pincer chelates, II. This implies a stabilization of a highly Lewis acidic iron(IV) center by four phenolate anions rather than charge distribution across the ligand framework with a lower formal oxidation state at iron. Notably, the overall charge-neutral iron(IV) complex undergoes reductive elimination of the pincer ligand, providing a metal-free compound that can be described as a spirocyclic imidazolone ketal (6). In contrast, the ligand-metal bonds in 5, formally an iron(V) complex, are considerably covalent, rendering the assignment of its oxidation state challenging, if not impossible. All compounds are fully characterized, and the complexes' electronic structures were studied with a variety of spectroscopic and computational methods, including single-crystal X-ray diffraction (SC-XRD), X-band electron paramagnetic resonance (EPR), and zero-field 57Fe Mössbauer spectroscopy, variable-field and variable-temperature superconducting quantum interference device (SQUID) magnetization measurements, and multi-reference ab initio (NEVPT2/CASSCF) as well as density functional theory (DFT) studies. Taken altogether, the electronic structure of 5 is best described as an iron(IV) center antiferromagnetically coupled to a ligand-centered radical. ©
CRIS-Team Scopus Importer:2020-04-24

An Isolable Terminal Imido Complex of Palladium and Catalytic Implications - Grünwald, Annette; Orth, Nicole; Scheurer, Andreas; Heinemann, Frank Wilhelm; Pöthig, Alexander; Munz, Dominik (Angewandte Chemie International Edition, 2018)
Keywords: C−H activation; palladium nitrene complexes; small-molecule activation; homogeneous catalysis; palladium imido complexes

Anisotropic Magnetic Supraparticles with a Magnetic Particle Spectroscopy Fingerprint as Indicators for Cold-Chain Breach - Müssig, Stephan; Granath, Tim; Schembri, Tim; Fidler, Florian; Haddad, Daniel; Hiller, Karl-Heinz; Wintzheimer, Susanne; Mandel, Karl (ACS Applied Nano Materials, 2019)
Magnetic particle spectroscopy (MPS) is used in this work to obtain a magnetic fingerprint signal from anisotropic supraparticles, i.e., microrods assembled from superparamagnetic iron oxide nanoparticles. Exceeding its intended purpose of nanoparticle characterization for biomedical magnetic particle imaging, it is shown that MPS is capable of resolving structural differences between the anisotropic alignment of individual nanoparticles and its isotropic counterpart. Additionally, orientation-dependent MPS signal variations of anisotropic supraparticles are identifiable. This finding enables the detection of cold-chain breaches (for instance, during delivery of a product that needs to be cooled all of the time) by recording the initial and final MPS signals of microrod samples integrated into the container of a frozen product.
CRIS-Team Scopus Importer:2020-04-02
Keywords: cold-chain breach; detectors; magnetic particle spectroscopy; magnetic particles; magnetic sensor; supraparticles

An iterative approach to cis-oligodiacetylenes - Kosinski, Christoph; Hirsch, Andreas; Heinemann, Frank Wilhelm; Hampel, Frank (European Journal of Organic Chemistry, 2001)
Phenyl-terminated cis-oligodiacetylenes such as 18, containing a π-conjugated backbone with four triple and three double bonds, were synthesized using Pd-catalysed Sonogashira coupling reactions. Compound 18 represents the longest cis-oligoenyne system to date, but it suffers from the drawback of cis/trans isomerization observed in solution. In order to avoid cis/trans isomerization in such cis-oligodicacetylenes, the ene moieties within the oligomeric backbone were locked by incorporation into ring systems. 1,2-Dibromocyclopentene was used as an olefinic building block for this purpose, permitting the iterative synthesis of the cis-oligodiacetylenes 27 and 28, possessing the same π-conjugated backbone as 18. Unlike that compound, however, 27 and 28 are stable both in solution and in the solid state. Whereas X-ray crystallography revealed a completely planar structure for 27 in the single crystal, NMR and computational investigations suggest that a preferred helical conformation is likely in solution.

Anodes for Li-ion batteries prepared from microcrystalline silicon and enabled by binder’s chemistry and pseudo-self-healing - Foss, Carl Erik Lie; Müssig, Stephan; Svensson, Ann Mari; Vie, Preben J. S.; Ulvestad, Asbjørn; Mæhlen, Jan Petter; Koposov, Alexey Y. (Scientific Reports, 2020)
Silicon, while suffering from major degradation issues, has been recognized as a next promising material to replace currently used graphite in the anodes of Li-ion batteries. Several pathways to mitigate the capacity fading of silicon has been proposed, including optimization of the electrode composition. Within the present work we evaluated different binder formulations to improve the long-term performance of the Li-ion batteries’ anodes based on industrial grade silicon (Si) which is typically characterized by a particle sizes ranging from 100 nm to 5.5 microns. The decrease of pH in a binder formulation was found to detrimental for the cycling performance of Si due to enhanced formation of an ester-type bonding between the carboxylic group of the binder and hydroxyl group on the Si surface as well as cross-linking. Furthermore, the present work was focused on the use of the industrial grade Si with very high loading of Si material (up to 80% by weight) to better highlight the effects of the surface chemistry of Si and its influence on the performance of Si-based anodes in Li-ion batteries. The tested system allowed to establish a pseudo self-healing effect that manifests itself through the restoration of the anode capacity by approximately 25% and initiates after approximately 20 cycles. The stabilization of the capacity is attributed to self-limiting lithiation process. Such effect is closely related to SEI formation and transport properties of an electrode prepared from silicon of industrial grad

A non-heme dinuclear iron(II) complex containing a single, unsupported hydroxo bridge - Heinemann, Frank Wilhelm; et al. (Chemical Communications, 2006)

A novel five-coordinate mn complex with a redox-active snnns ligand system - Dürr, Katharina L.; Yalalov, Denis A.; Heinemann, Frank Wilhelm; Tsogoeva, Svetlana; Ivanovic-Burmazovic, Ivana (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2010)
Synthesis and characterization of a manganese complex of a new redox-active diaminocyclohexane derivative of a thiourea-based ligand with SNNNS donor atom set is reported. The molecular structure of the complex exhibits a pentadentate SNNNS ligand coordinated in the neutral form to the Mn(II) center. The coordination around the central metal is best described as distorted trigonal bipyramidal with the pyridine nitrogen and the two sulfur atoms being in the equatorial plane and the remaining two nitrogen donors occupying the apical positions of the bipyramid. Cyclic voltammetry in DMSO shows the Mn /Mn redox couple with the oxidation peak at -0.199 V and the reduction peak at -0.587 V vs. Fc/Fc (scan rate 0.5 V s ). The ligand itself possesses redox activity and exhibits prominent oxidation and reduction peaks at -1.194 and -1.481 V vs. Fc/Fc , respectively. The results of electrochemical experiments under oxygen atmosphere suggest that upon reaction with electrochemically generated superoxide the redox-active ligand is modified causing decomposition of the complex. © 2010 Verlag der Zeitschrift für Naturforschung, Tübingen.

Anticancer Effect of an Electronically Coupled Oligoferrocene - Zeh, Gina; Haines, Philipp; Miehlich, Matthias; Kienz, Torben; Neidlinger, Andreas; Friedrich, Ralf P.; Alexiou, Christoph; Hampel, Frank; Guldi, Dirk Michael; Meyer, Karsten; Schatz, Jürgen; Heinze, Katja; et al. (Organometallics, 2020)
The mode of anticancer activity of simple ferrocenes often relies on their intracellular oxidation with the formation of cytotoxic ferrocenium species. The former compounds should be considered as prodrugs and derived from them ferroceniums as drugs. The drugs are 17e- organometallic species. Therefore, they are chemically unstable and decompose with formation of free cyclopentadienyl ligands (which are further transformed to more stable species) and iron ions. The short lifetime of ferrocenium drugs limits the anticancer effect of ferrocene prodrugs. In this paper we prepared a series of acylated aminoferrocene monomers, dimers, and higher oligonuclear complexes FcN (where N = 1-4). Drugs [FcN]+ derived from FcN (N > 1) are more stable than monomeric [Fc]+, provided that the ferrocene units are electronically coupled. Correspondingly, we expected that FcN species will be more potent anticancer agents in comparison to the related monomers. These assumptions were confirmed for dimer 10. We observed that this prodrug has sufficient solubility in aqueous solution (100 μM) and favorable lipophilicity (log P = 2.2 ± 0.2). Ferrocene units in 10 are efficiently electronically coupled via a -C(═O)NH- linker according to cyclic voltammetry, differential pulse voltammetry, and spectroelectrochemistry. We observed that 10 is the most efficient catalyst of the production of reactive oxygen species (ROS) and the most active anticancer agent in comparison to control monomers and their mixtures.
CRIS-Team Scopus Importer:2020-09-14

"Anti-electrostatic" Halogen Bonding between Ions of Like Charge - Holthoff, Jana M.; Weiss, Robert; Rosokha, Sergiy; Huber, Stefan M. (Chemistry - A European Journal, 2021)
Halogen bonding occurs between molecules featuring Lewis acidic halogen substituents and Lewis bases. It is often rationalized as a predominantly electrostatic interaction and thus interactions between ions of like charge (e. g., of anionic halogen bond donors with halides) seem counter-intuitive. Herein, we provide an overview on such complexes. First, theoretical studies are described and their findings are compared. Next, experimental evidences are presented in the form of crystal structure database analyses, recent examples of strong "anti-electrostatic" halogen bonding in crystals, and the observation of such interactions also in solution. We then compare these complexes to select examples of "counter-intuitive" adducts formed by other interactions, like hydrogen bonding. Finally, we comment on key differences between charge-transfer and electrostatic polarization.
CRIS-Team WoS Importer:2021-10-08

“Anti-Electrostatic” Halogen Bonding - Holthoff, Jana M.; Engelage, Elric; Weiss, Robert; Huber, Stefan M. (Angewandte Chemie International Edition, 2020)
Halogen bonding is often described as being driven predominantly by electrostatics, and thus adducts between anionic halogen bond (XB) donors (halogen-based Lewis acids) and anions seem counterintuitive. Such “anti-electrostatic” XBs have been predicted theoretically but for organic XB donors, there are currently no experimental examples except for a few cases of self-association. Reported herein is the synthesis of two negatively charged organoiodine derivatives that form anti-electrostatic XBs with anions. Even though the electrostatic potential is universally negative across the surface of both compounds, DFT calculations indicate kinetic stabilization of their halide complexes in the gas phase and particularly in solution. Experimentally, self-association of the anionic XB donors was observed in solid-state structures, resulting in dimers, trimers, and infinite chains. In addition, co-crystals with halides were obtained, representing the first cases of halogen bonding between an organic anionic XB donor and a different anion. The bond lengths of all observed interactions are 14–21 % shorter than the sum of the van der Waals radii.
CRIS-Team Scopus Importer:2020-05-08
Keywords: density-functional calculations; electrostatics; halogen bonding; hydrogen bonding; noncovalent interactions

"Anti-electrostatic" halogen bonding in solution - Loy, Cody; Holthoff, Jana M.; Weiss, Robert; Huber, Stefan M.; Rosokha, Sergiy V. (Chemical Science, 2021)
Halogen-bonded (XB) complexes between halide anions and a cyclopropenylium-based anionic XB donor were characterized in solution for the first time. Spontaneous formation of such complexes confirms that halogen bonding is sufficiently strong to overcome electrostatic repulsion between two anions. The formation constants of such "anti-electrostatic" associations are comparable to those formed by halides with neutral halogenated electrophiles. However, while the latter usually show charge-transfer absorption bands, the UV-Vis spectra of the anion-anion complexes examined herein are determined by the electronic excitations within the XB donor. The identification of XB anion-anion complexes substantially extends the range of the feasible XB systems, and it provides vital information for the discussion of the nature of this interaction.
CRIS-Team WoS Importer:2021-05-28

Antimony sulfide as a light absorber in highly ordered, coaxial nanocylindrical arrays: preparation and integration into a photovoltaic device - Wu, Yanlin; Assaud, Loic; Kryschi, Carola; Capon, Boris; Detavernier, Christophe; Santinacci, Lionel; Bachmann, Julien (Journal of Materials Chemistry A, 2015)
We demonstrate the preparation of functional 'extremely thin absorber' solar cells consisting of massively parallel arrays of nanocylindrical, coaxial n-TiO2/i-Sb2S3/p-CuSCN junctions. Anodic alumina is used as an inert template that provides ordered pores of 80 nm diameter and 1-50 mu m length. Atomic layer deposition (ALD) then coats pores of up to 20 mm with thin layers of the electron conductor and the intrinsic light absorber. The crystallization of the initially amorphous Sb2S3 upon annealing is strongly promoted by an underlying crystalline TiO2 layer. After the remaining pore volume is filled with the hole conductor by solution evaporation, the resulting coaxial p-i-n junctions display stable diode and photodiode electrical characteristics. A recombination timescale of 40 ms is extracted from impedance spectroscopy in open circuit conditions, whereas transient absorption spectroscopy indicates that holes are extracted from Sb2S3 with a lifetime of 1 ns.

A Pair of Cobalt(III/IV) Terminal Imido Complexes - Mao, Weiqing; Fehn, Dominik; Heinemann, Frank Wilhelm; Scheurer, Andreas; Munz, Dominik; Meyer, Karsten (Angewandte Chemie International Edition, 2021)
The reaction of the cobalt(I) complex [(TIMMNmes)Co-I](BPh4) (2) (TIMMNmes=tris-[2-(3-mesitylimidazolin-2-ylidene)methyl]amine) with 1-adamantylazide yields the cobalt(III) imido complex [(TIMMNmes)Co-III(NAd)](BPh4) (3) with concomitant release of dinitrogen. The N-anchor in diamagnetic 3 features an unusual, planar tertiary amine, which results from repulsive electrostatic interaction with the filled d(z(2))-orbital of the cobalt ion and negative hyperconjugation with the neighboring methylene groups. One-electron oxidation of 3 with [FeCp2](OTf) provides access to the rare, high-valent cobalt(IV) imido complex [(TIMMNmes)Co-IV(NAd)](OTf)(2) (4). Despite a half-life of less than 1 h at room temperature, 4 could be isolated at low temperatures in analytically pure form. Single-crystal X-ray diffractometry and EPR spectroscopy corroborate the molecular structure and the d(5) low-spin, S=1/2 , electron configuration. A computational analysis of 4 suggests high covalency within the Co-IV=NAd bond with non-negligible spin density located at the imido moiety, which translates into substantial triplet nitrene character.
CRIS-Team WoS Importer:2021-06-25

A pentadentate member of the picolinate family for Mn(ii) complexation and an amphiphilic derivative - Pujales Paradela, Rosa; et al. (Dalton Transactions, 2019)
We report a pentadentate ligand containing a 2,2-azanediyldiacetic acid moiety functionalized with a picolinate group at the nitrogen atom (H(3)paada), as well as a lipophylic derivative functionalized with a dodecyloxy group at position 4 of the pyridyl ring (H(3)C(12)Opaada). The protonation constants of the paada(3-) ligand and the stability constant of the Mn(ii) complex were determined using a combination of potentiometric and spectrophotometric titrations (25 degrees C, 0.15 M NaCl). A detailed relaxometric characterisation was accomplished by recording H-1 Nuclear Magnetic Relaxation Dispersion (NMRD) profiles and O-17 chemical shifts and relaxation rates. These studies provide detailed information on the microscopic parameters that control their efficiency as relaxation agents in vitro. For the sake of completeness and to facilitate comparison, we also characterised the related [Mn(nta)](-) complex (nta = nitrilotriacetate). Both the [Mn(paada)](-) and [Mn(nta)](-) complexes turned out to contain two inner-sphere water molecules in aqueous solution. The exchange rate of these coordinated water molecules was slower in [Mn(paada)](-) (k298ex = 90 x 10(7) s(-1)) than in [Mn(nta)](-) (k298ex = 280 x 10(7) s(-1)). The complexes were also characterised using both DFT (TPSSh/def2-TZVP) and ab initio CAS(5,5) calculations. The lipophylic [Mn(C(12)Opaada)](-) complex forms micelles in solution characterised by a critical micellar concentration (cmc) of 0.31 +/- 0.01 mM. This complex also forms a rather strong adduct with Bovine Serum Albumin (BSA) with an association constant of 5.5 x 10(4) M-1 at 25 degrees C. The enthalpy and entropy changes obtained for the formation of the adduct indicate that the binding event is driven by hydrophobic interactions.

A planar three-coordinate vanadium(II) complex and the study of terminal vanadium nitrides from N 2: A kinetic or thermodynamic impediment to N-N bond cleavage? - Tran, Ba L.; Pinter, Balazs; Nichols, Adam J.; Konopka, Felicia T.; Thompson, Rick; Chen, Chun-Hsing; Krzystek, J.; Ozarowski, Andrew; Telser, Joshua; Baik, Mu-Hyun; Meyer, Karsten; Mindiola, Daniel J. (Journal of the American Chemical Society, 2012)
We report the first mononuclear three-coordinate vanadium(II) complex [(nacnac)V(ODiiP)] and its activation of N to form an end-on bridging dinitrogen complex with a topologically linear V(III)N V(III) core and where each vanadium center antiferromagnetically couples to give a ground state singlet with an accessible triplet state as inferred by HFEPR spectroscopy. In addition to investigating the conversion of N to the terminal nitride (as well as the microscopic reverse process), we discuss its similarities and contrasts to the isovalent d system, [Mo(N[ Bu]Ar) ], and the S = 1 system [(Ar[ Bu]N) Mo] (μ - η :η -N ). © 2012 American Chemical Society.

A Potent Auto-Umpolung Ligand for Conjugative Radical Stabilization - Holthoff, Jana M.; Engelage, Elric; Ruff, Adrian; Galazzo, Laura; Bordignon, Enrica; Huber, Stefan M.; Weiss, Robert (Chemistry - A European Journal, 2022)
Carbenes with conjugatively connected redox system act as "auto-umpolung" ligands. Due to their electronic flexibility, they should also be particularly suitable to stabilize open-shell species. Herein, the first neutral radical of such sort is described in form of a dialkylamino-substituted bis(dicyanomethylene)cyclopropanide. Despite the absence of steric shielding, the radical is stable for an extended amount of time and was consequently characterized in solution via EPR measurements. These data and accompanying X-ray structural analyses indicate that the radical species is in equilibrium with aggregates (formed via pi-stacking) and dimers (obtained via sigma-bond formation between methylene carbons).
CRIS-Team WoS Importer:2022-12-16

A practical route to regiospecifically substituted (R)- and (S)-oxazolylphenols - Scheurer, Andreas; et al. (European Journal of Organic Chemistry, 2001)
Keywords: Amino alcohols; Nitrogen heterocycles; Chirality; Salicylic acids; Oxazolines

Aquabis(salicyl-aldoximato) zinc - Potocnak, I.; Heinemann, Frank Wilhelm; Rausch, M.; Steinborn, Dirk (Acta Crystallographica Section C: Crystal Structure Communications, 1997)

A Roadmap for Transforming Research to Invent the Batteries of the Future Designed within the European Large Scale Research Initiative BATTERY 2030+ - Amici, Julia; Asinari, Pietro; Ayerbe, Elixabete; Barboux, Philippe; Bayle-Guillemaud, Pascale; Behm, R. Juergen; Berecibar, Maitane; Berg, Erik; Bhowmik, Arghya; Bodoardo, Silvia; Castelli, Ivano E.; Cekic-Laskovic, Isidora; et al. (Advanced Energy Materials, 2022)
This roadmap presents the transformational research ideas proposed by "BATTERY 2030+," the European large-scale research initiative for future battery chemistries. A "chemistry-neutral" roadmap to advance battery research, particularly at low technology readiness levels, is outlined, with a time horizon of more than ten years. The roadmap is centered around six themes: 1) accelerated materials discovery platform, 2) battery interface genome, with the integration of smart functionalities such as 3) sensing and 4) self-healing processes. Beyond chemistry related aspects also include crosscutting research regarding 5) manufacturability and 6) recyclability. This roadmap should be seen as an enabling complement to the global battery roadmaps which focus on expected ultrahigh battery performance, especially for the future of transport. Batteries are used in many applications and are considered to be one technology necessary to reach the climate goals. Currently the market is dominated by lithium-ion batteries, which perform well, but despite new generations coming in the near future, they will soon approach their performance limits. Without major breakthroughs, battery performance and production requirements will not be sufficient to enable the building of a climate-neutral society. Through this "chemistry neutral" approach a generic toolbox transforming the way batteries are developed, designed and manufactured, will be created.
CRIS-Team WoS Importer:2022-01-28
Keywords: battery 2030+ roadmap; battery interface genome; chemistry neutral approach; manufacturing; materials acceleration platform; recycling; smart battery functionalities

Aromatic interactions in unusual backbone nitrogen-coordinated zinc peptide complexes: A crystallographic and spectroscopic study - Heinemann, Frank Wilhelm; Zahl, Achim; et al. (Inorganic Chemistry, 2005)
A series of zinc complexes with dipeptide ligands of the type Dpg-Xaa was synthesized, where Dpg is dipicolylglycine and Xaa is phenylalanine (Phe), tyrosine (Tyr), tryptophan (Trp), 2-naphthylalanine (Nal), or glycine (Gly). It was shown that aromatic interactions promote the unusual coordination of an anionic peptide backbone nitrogen atom to zinc. This binding mode was, for the first time, characterized by X-ray structure analyses of the electrically neutral complexes [(Dpg-Phe)Zn], [(Dpg-Tyr)Zn], [(Dpg-Trp)Zn], and [(Dpg-Nal)Zn]. The pK values for amide nitrogen deprotonation were determined by H NMR titrations [(Dpg-Phe)Zn], 7.17; [(Dpg-Tyr)Zn], 6.85; [(Dpg-Trp)Zn], 6.85; [(Dpg-Nal)Zn], 6.64; [(Dpg-Gly)Zn], 8.54. It was calculated that aromatic interactions contribute ca. -8 to -11 kJ/mol of stabilizing free enthalpy changes in the derivatives with aromatic amino acid side chains. These are the first quantitative data obtained for crystallographically characterized metal complexes. A comparison with the literature shows that it is difficult to distinguish between π-cation attraction and π-π stacking. However, it is evident that modification of small peptides with synthetic pyridine ligands enhances their ability to stabilize secondary structures by noncovalent interactions. This is an important consideration for the design of biomimetic metallopeptides. © 2005 American Chemical Society.

Aromaticity and sterics control whether a cationic olefin radical is resistant to disproportionation - Messelberger, Julian; Grünwald, Annette; Goodner, Stephen J.; Zeilinger, Florian; Pinter, Piermaria; Miehlich, Matthias; Heinemann, Frank Wilhelm; Hansmann, Max M.; Munz, Dominik (Chemical Science, 2020)
We elucidate why some electron rich-olefins such as tetrathiafulvalene (TTF) or paraquat (1,1 '-dimethyl-4,4 '-bipyridinylidene) form persistent radical cations, whereas others such as the dimer of N,N '-dimethyl benzimidazolin-2-ylidene (benzNHC) do not. Specifically, three heterodimers derived from cyclic (alkyl) (amino) carbenes (CAAC) with N,N '-dimethyl imidazolin-2-ylidene (NHC), N,N '-dimethyl imidazolidin-2-ylidene (saNHC) and N-methyl benzothiazolin-2-ylidene (btNHC) are reported. Whereas the olefin radical cations with the NHC and btNHC are isolable, the NHC compound with a saturated backbone (saNHC) disproportionates instead to the biscation and olefin. Furthermore, the electrochemical properties of the electron-rich olefins derived from the dimerization of the saNHC and btNHC were assessed. Based on the experiments, we propose a general computational method to model the electrochemical potentials and disproportionation equilibrium. This method, which achieves an accuracy of 0.07 V (0.06 V with calibration) in reference to the experimental values, allows for the first time to rationalize and predict the (in)stability of olefin radical cations towards disproportionation. The combined results reveal that the stability of heterodimeric olefin radical cations towards disproportionation is mostly due to aromaticity. In contrast, homodimeric radical cations are in principle isolable, if lacking steric bulk in the 2,2 ' positions of the heterocyclic monomers. Rigid tethers increase accordingly the stability of homodimeric radical cations, whereas the electronic effects of substituents seem much less important for the disproportionation equilibrium.
CRIS-Team WoS Importer:2020-05-26

A Room-Temperature Stable Y(II) Aryloxide: Using Steric Saturation to Kinetically Stabilize Y(II) Complexes - Moehring, Samuel A.; Miehlich, Matthias; Hörger, Christopher; Meyer, Karsten; Ziller, Joseph W.; Evans, William J. (Inorganic Chemistry, 2020)
The utility of the bulky aryloxide ligands 2,6-Ad2-4-Me-C6H2O- (Ad,Ad,MeArO-) and 2,6-Ad2-4-t-Bu-C6H2O- (Ad,Ad,t-BuArO- Ad = 1-adamantyl) for stabilizing the Y(II) ion is reported and compared with the results with 2,6-t-Bu2-4-Me-C6H2O- (Ar′O-). In contrast to the reduction product obtained from reducing Y(OAr′)3 with potassium graphite, which is only stable in solution for 60 s at room temperature, KC8 reduction of Y(OArAd,Ad,t-Bu)3 in THF in the presence of 2.2.2-cryptand (crypt) produces the room-temperature stable, crystallographically characterizable Y(II) aryloxide [K(crypt)][Y(OArAd,Ad,t-Bu)3]. The X-band EPR spectrum at 77 K shows an axial pattern with resonances centered at g= 1.97 and g= 2.00 and hyperfine coupling constants of A = 156.5 G and A= 147.8 G and at room temperature shows an isotropic pattern with giso = 1.98 and Aiso = 153.3 G, which is consistent with an S = 1/2 spin system with nuclear spin I = 1/2 for the 89Y isotope (100% natural abundance).
CRIS-Team Scopus Importer:2020-03-06

Arrested disproportionation in trivalent, mononuclear, and non-metallocene complexes of Zr(III) and Hf(III) - Grant, Lauren N.; Miehlich, Matthias; Meyer, Karsten; Mindiola, Daniel J. (Chemical Communications, 2018)
Reduction of the group 4 transition metal precursors [(PN)2MCl2] (M = Zr (1), and Hf (2)); PN- = (N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide), both readily prepared by transmetallation of 2 LiPN with [MCl4(THF)2], with a slight excess of KC8, resulted in the isolation of the trivalent complexes [(PN)2MCl] (M = Zr (3), and Hf (4)). Complexes 1-4 were all identified by solid-state X-ray diffraction analysis, whereas in the case of 3 and 4 low temperature X-band EPR spectroscopy allowed for the identification of these metal-centered d1 radicals. A comparison with the isostructural and isoelectronic but more stable [(PN)2TiCl] is also presented.
CRIS-Team Scopus Importer:2020-09-14

Aryl, methyl-diplatinum complexes each with a metal-metal donor-acceptor bond and bridging 2-diphenylphosphinopyridine (PN) ligands: general synthetic approach and mechanism of isomerization - Heinemann, Frank Wilhelm; et al. (Dalton Transactions, 2007)
A general synthetic method has been designed to prepare a series of unsymmetrical cationic organo-diplatinum complexes each containing two bridging 2-diphenylphosphinopyridine (PN), PPh(2)py, ligands and a platinum - platinum donor - acceptor bond. Thus, reaction of cis-[PtR2(SMe2)(2)] (R = Ph, p-MeC6H4 or p-FC6H4), 1, or cis,cis-[R2Pt(mu-SMe2)(2)PtR2](R = Me) with 2 equiv. or 4 equiv., respectively, of PN in CH2Cl2 gave cis-[PtR2(PN-kappa P-1)(2)], 2. When complex 2 was reacted with 1 equiv. of HX (X = CF3COO) in CH2Cl2, an approximately 2 : 1 mixture of trans-[PtRX(PN-kappa P-1)(2)], 3, and [PtR(eta(2)-PN)(PN-kappa P-1)]X, 4, was obtained. The reaction of one equiv. of the latter monomeric mixture with 0.5 equiv. of cis, cis-[R'Pt-2(mu-SMe2)(2)PtR'(2)](R' = Me)or one equiv. of cis-[PtR'(2)(SMe2)(2)](R' = p- MeC6H4) in CH2Cl2 immediately gave the head-to-head (HH) stereoisomer of the diplatinum complex hh-[RPt(mu-PN)(2)PtR'(2)]X, 6. However, the same reaction in benzene gave the corresponding head-to-tail (HT) stereoisomer ht-[RPt(mu-PN)(mu-NP)PtR'(2)]X, 9, in pure form after a few hours. The conversion of the HH isomer 6 to the HT isomer 9 in CH2Cl2 took place very slowly during 10 d, while the conversion in C6H6 was much faster and took place over 5 h. Based on the observations, a mechanism for the conversion of the kinetic HH stereoisomer to the thermodynamic HT stereoisomer is suggested which involves association of X- with the N2PtR'(2) center following by one-arm dissociation of one of the PN bridging ligands from the nitrogen terminal in the HH isomer, and subsequent exchange of the ligating atom and reformation of the HT arrangement. The methyl-dip-tolyl dimer ht-[MePt(mu-PN)(mu-NP)Pt(p-MeC6H4)(2)]X, 9e, in solution gradually isomerizes to ht-[(p-MeC6H4)Pt(mu-PN)(mu-NP)PtMe(p-MeC6H4)]X, 11, by an aryl ligand transfer. All the complexes were fully characterized using multinuclear (H-1, P-31 and Pt-195) NMR spectroscopy and the complexes ht-[PhPt(mu-PN)(mu-NP)PtMe2]X, 9a, and ht-[(p-MeC6H4)Pt(mu-PN)(mu-NP)PtMe(p-MeC6H4)]X, 11, were further characterized by single crystal X-ray crystallography.

A Self‐Ordered Nanostructured Transparent Electrode of High Structural Quality and Corresponding Functional Performance - Döhler, Dirk; Triana Merlo, Andres Dario; Büttner, Pascal; Scheler, Florian; Görlitzer, Eric; Harrer, Johannes; Vasileva, Anna A.; Ali, Ezzeldin; Gruber, Wolfgang; Unruh, Tobias; Manshina, Alina A.; Vogel, Nicolas; et al. (Small, 2021)
The preparation of a highly ordered nanostructured transparent electrode based on a combination of nanosphere lithography and anodization is presented. The size of perfectly ordered pore domains is improved by an order of magnitude with respect to the state of the art. The concomitantly reduced density of defect pores increases the fraction of pores that are in good electrical contact with the underlying transparent conductive substrate. This improvement in structural quality translates directly and linearly into an improved performance of energy conversion devices built from such electrodes in a linear manne
Keywords: nanosphere lithography; anodic alumina; antimony sulfide

A Series of Discrete Dichloride Dihydrates: Characterisation and Symmetry Effects - Senthooran, Rathiga; Curnow, Owen J.; Brenner, Thomas; Weiss, Robert; Ferreras, Manuel; Crittenden, Deborah L. (ChemPlusChem, 2020)
A series of three discrete dichloride dihydrates [Cl2(H2O)2]2− have been isolated with different triaminocyclopropenium (TAC) cations and with different crystallographic symmetries. The cluster exhibits D2h symmetry with the tris(dimethylamino)cyclopropenium cation [C3(NMe2)3]+, C2h symmetry with the fluorinated cation [C3(N(CH2CF3)2)(NBu2)2]+ (containing two 2,2,2-trifluoroethyl substituents) and C2v symmetry with the more fluorinated [C3(N(CH2CF3)2)2(NBu2)]+ cation. The effect of symmetry on the infrared spectra of the dichloride ion-pair clusters, as well as deuterated analogues, has been investigated. The D2h- and C2h-symmetric clusters each exhibit two stretching bands in the infrared at 3427 and 3368 cm−1 for D2h symmetry and 3444 and 3392 cm−1 for C2h symmetry, whereas the C2v-symmetric cluster exhibits three bands at 3475, 3426 and 3373 cm−1. Computational studies were carried out on a [Cl2(H2O)2]2− cluster with C2v symmetry to aid the infrared band assignments.
CRIS-Team Scopus Importer:2020-09-18
Keywords: cyclopropenium cations; dichlorides; hydrates; ion-pair clusters; symmetry

A Series of Iron Nitrosyl Complexes Fe-NO6-9 and a Fleeting FeNO10 Intermediate en route to a Metalacyclic Iron Nitrosoalkane - Keilwerth, Martin; Hohenberger, Johannes; Heinemann, Frank Wilhelm; Sutter, Jörg; Scheurer, Andreas; Fang, Huayi; Bill, Eckhard; Neese, Frank; Ye, Shengfa; Meyer, Karsten (Journal of the American Chemical Society, 2019)
Iron-Nitrosyls have fascinated chemists for a long time due to the non-innocent nature of the NO ligand that can exist in up to five different oxidation and spin states. Coordination to an open-shell iron center leads to complex electronic structures, which is the reason Enemark and Feltham introduced the Fe-NOn notation.1 In this work, we succeeded to characterize a series of Fe-NO6-9 complexes, including a reactive Fe-NO10 intermediate. All complexes were synthesized with the tris-N-heterocyclic carbene ligand tris[2-(3-mesityl-imidazol-2-ylidene)ethyl]amine (TIMENMes), which is known to support iron in high and low oxidation states. Reaction of NOBF4 with [(TIMENMes)Fe]2+ resulted in formation of the Fe-NO6 compound [(TIMENMes)Fe(NO)(CH3CN)](BF4)3, (1). Stepwise chemical reduction with Zn, Mg, and Na/Hg leads to the isostructural series of high-spin iron nitrosyl complexes Fe-NO7,8,9 (2 - 4). Reduction of Fe-NO9 with Cs electride finally yields the highly reduced Fe-NO10 intermediate, key to formation of [Cs[2.2.2.]crypt][(TIMENMes)Fe(NO)], (5) featuring a metalacyclic Fe-NHC(NO)3− nitrosoalkane unit. All complexes were characterized by single-crystal XRD analyses, temperature and field-dependent SQUID magnetization methods as well as 57Fe Mössbauer, IR, UV/vis, multi-nuclear NMR, and dual-mode EPR spectroscopy. Spectroscopy-based DFT analyses provide insight into the electronic structures of all compounds and allowed assignments of oxidation states to iron and NO ligands. An alternative synthesis to the Fe-NO8 complex was found via oxygenation of the nitride complex [(TIMENMes)Fe(N)](BF4). Surprisingly, the resulting Fe-NO8 species is electronically and structural similar to the [(TIMENMes)Fe(N)]+ precursor. Based on the structural and electronic similarities between this nitrosyl/nitride complex couple, we adopted the strategy, developed by Wieghardt et al.,1 of extending the Enemark & Feltham nomenclature to nitrido complexes, rendering [(TIMENMes)Fe(N)]+ as a Fe-N8 species.
CRIS-Team Scopus Importer:2019-10-22

A series of metal complexes with the non-innocent N,N’-bis(pentafluorophenyl)-o-phenylenediamido ligand: twisted geometry for tuning the electronic structure - Khusniyarov, Marat; Harms, Klaus; Sundermeyer, Jörg; Sarkar, Biprajit; Kaim, W.; van Slageren, J.; Duboc, C.; Fiedler, Jan (Dalton Transactions, 2008)

A series of uranium (IV, V, VI) tritylimido complexes, their molecular and electronic structures and reactivity with CO2. - Schmidt, Anna-Corina; Heinemann, Frank Wilhelm; Maron, Laurent; Meyer, Karsten (Inorganic Chemistry, 2014)
A series of uranium tritylimido complexes with structural continuity across complexes in different oxidation states, namely U(IV), U(V), and U(VI), is reported. This series was successfully synthesized by employing the trivalent uranium precursor, [(((nP,Me)ArO)3tacn)U(III)] (1) (where ((nP,Me)ArO)3tacn(3-) = trianion of 1,4,7-tris(2-hydroxy-5-methyl-3-neopentylbenzyl)-1,4,7-triazacyclononane), with the organic azides Me3SiN3, Me3SnN3, and Ph3CN3 (tritylazide). While the reaction with Me3SiN3 yields an inseparable mixture of both the azido and imido uranium complexes, applying the heavier Sn homologue yields the bis-μ-azido complex [(((nP,Me)ArO)3tacn)U(IV)2(μ-N3)2] (2) exclusively. In contrast to this one-electron redox chemistry, the reaction of precursor 1 with tritylazide solely leads to the two-electron oxidized U(V) imido [(((nP,Me)ArO)3tacn)U(V)(N-CPh3)] (3). Oxidation and reduction of 3 yield the corresponding U(VI) and U(IV) complexes [(((nP,Me)ArO)3tacn)U(VI)(N-CPh3)][B(C6F5)4] (4) and K[(((nP,Me)ArO)3tacn)U(IV)(N-CPh3)] (5), respectively. In addition, the U(V) imido 3 engages in a H atom abstraction reaction with toluene to yield the closely related amido complex [(((nP,Me)ArO)3tacn)U(IV)(N(H)-CPh3)] (6). Complex 6 and the three tritylimido complexes 3, 4, and 5, with oxidation states ranging from +IV to +VI and homologous core structures, were investigated by X-ray diffraction analyses and magnetochemical and spectroscopic studies as well as density functional theory (DFT) computational analysis. The series of structurally very similar imido complexes provides a unique opportunity to study electronic properties and to probe the uranium imido reactivity solely as a function of electron count of the metal-imido entity. Evidence for the U-N bond covalency and f-orbital participation in complexes 3-6 was drawn from the in-depth and comparative DFT study. The reactivity of the imido and amido complexes with CO2 was probed, and conclusions about the influence of the formal oxidation state are reported.

A Simple Model Setup Using Spray-Drying Principles and Fluorescent Silica Nanoparticles to Evaluate the Efficiency of Facemask Materials in Terms of Virus Particle Retention - Oppmann, Maximilian; Wenderoth, Sarah; Ballweg, Thomas; Schug, Benedikt; Mandel, Karl (Advanced Materials Technologies, 2021)
Herein, a simple model setup is presented to spray fine liquid droplets containing nanoparticles in an air stream transporting this toward a filter material. The nanoparticles are made of silica and tagged with a fluorescent dye in order to render the trace of the particles easily visible. The silica nanoparticles, in a first approximation, mimic virus (severe acute respiratory syndrome coronavirus 2) particles. The setup is used to evaluate different tissues, nowadays, in times of the coronavirus pandemic, commonly used as facemasks, with regard to their particle retention capability. The setup enables adjusting different “breathing scenarios” by adjusting the gas flow speed and, thereby, to compare the filter performance for these scenarios. The effective penetration of particles can be monitored via fluorescence intensity measurements and is visualized via scanning electron micrographs and photographs under UV light. Ultimately, a strong increase of particle penetration in various mask materials as function of flow speed of the droplets is observed and an ultimate retention is only observed for FFP3 and FFP2 masks.
CRIS-Team Scopus Importer:2021-05-21
Keywords: aerosol; Corona; COVID-19; facemask; FFP2; mask test; virus barrier

A Single Magnetic Particle with Nearly Unlimited Encoding Options - Müssig, Stephan; Reichstein, Jakob; Prieschl, Johannes; Wintzheimer, Susanne; Mandel, Karl (Small, 2021)
Communicating objects are demanded for product security and the concepts of a circular economy or the Internet of Nano Things. Smart additives in the form of particles can be the key to equip objects with the desired materials intelligence as their miniaturized size improves applicability and security. Beyond their proposed identification by optical signals, magnetic signals deriving from magnetic particles can hypothetically be used for identification but are to date only resolved roughly. Herein, a magnetic particle-based toolbox is reported, that provides more than 77 billion (77 × 109) different magnetic codes, adjustable in one single particle, that can be read out unambiguously, easily, and quickly. The key towards achieving the vast code variety is a hierarchical supraparticle design that is inspired by music: similarly to how the line-up variation of a musical ensemble yields distinguishable overtones, the variation of the supraparticle composition alters their magnetic overtones. By minimizing magnetic interactions, customizable signals are spectrally decoded by the simple method of magnetic particle spectroscopy. A large number of chemically adjustable magnetic codes and the possibility of their remote, contactless detection from within materials is a breakthrough for unexploited labeling applications and pave the way towards materials intelligence.
CRIS-Team Scopus Importer:2021-06-11
Keywords: identification; magnetic supraparticles; markers; tracers

A solution-based ALD route towards (CH3NH3)(PbI3) perovskite via lead sulfide films - Koch, Vanessa; Barr, Maissa; Büttner, Pascal; Mínguez-Bacho, Ignacio; Döhler, Dirk; Winzer, Bettina; Reinhardt, Elisabeth; Segets, Doris; Bachmann, Julien (Journal of Materials Chemistry A, 2019)
We present a procedure to grow thin films of lead sulfide (PbS) with 'solution Atomic Layer Deposition' (sALD), a technique which transfers the principles of ALD from the gas phase (gALD) to liquid processing. PbS thin films are successfully deposited on planar and porous substrates with a procedure that exhibits the unique ALD characteristics of self-limiting surface chemistry and linear growth at room temperature. The polycrystalline p-type PbS films are stoichiometric and pure. They are converted to the hybrid perovskite methylammonium iodoplumbate (methylammonium lead iodide, MAPI, CH3NH3PbI3) by annealing to 150 °C in the presence of vapors from methylammonium iodide (MAI).
CRIS-Team Scopus Importer:2019-11-19

A specific pi-ligand transfer reaction via triple-decker sandwich complex intermediates - Bohm, D.; Heinemann, Frank Wilhelm; Hu, D. Q.; Kummer, S.; Zenneck, Ulrich (Collection of Czechoslovak Chemical Communications, 1997)
Photochemically generated cationic cyclopentadienyl iron fragments [FeCp](+) allow a specific stacking reaction of [(t-Bu(3)C(3)P(2))Fe(t-Bu(2)C(2)P(3))]. This results in the transient formation of an unstable cationic Fe-Fe triple-decker sandwich complex which decomposes by deliberating the neutral sandwich complex [CpFe(t-Bu(2)C(2)P(3))], and is stacked again by a second [FeCp](+)-unit, yielding the moderately stable cationic triple-decker sandwich complex [CpFe(t-Bu(2)C(2)P(3))FeCp](+) with a central mu-eta(5):eta(5)-triphospholyl ligand. Air exposure or storage of solutions at room temperature leads to a destacking and the neutral triphosphaferrocene derivative [CpFe(t-Bu(2)C(2)P(3))] is formed again almost quantitatively in respect to the pentaphospha-ferrocene educt.
Keywords: iron compounds; triple-decker sandwich complexes; triphospholyl complexes

A specific route to enantiomerically pure asymmetric (eta(6)-arene)(eta(4)-1,5-cyclooctadiene)Ru(0) complexes - Heinemann, Frank Wilhelm; Klodwig, Jens; Knoch, Falk; Wundisch, M.; Zenneck, Ulrich (Chemische Berichte, 1997)
Chiral or achiral (arene)(COD)Ru complexes can be made by replacing the eta(6)-ligands of (eta(4)-1,5-COD)(eta(6)-1,3,5-cyclooctatriene)Ru (1) or (eta(4)-1,5-COD)(eta(6)-naphthalene)Ru (2) by a suitable arene. This well known reaction has been extended to mono- and dibromoarenes and we report a novel route to substituted (arene)(COD)Ru species, utilizing (bromoarene)-(COD)Ru as starting materials. These facilitate a rapid bromine-lithium exchange reaction with nBuLi at low temperatures and the Lithiated species react readily with alkyl chloro-formates as electrophiles. By using chiral electrophiles [alkyl = (-)-menthyl] enantiomerically pure or diastereomeric complexes containing CO(2)R* groups are formed, depending on the symmetry of the original complex. A diastereomeric 1:1 mixture was separated by recrystallization. All (arene)-(COD)Ru complexes tested so far are useful as catalysts for the hydrogenation of simple alkenes at room temperature.
Keywords: arene complexes; ruthenium compounds; electrophilic substitution; lithiation; catalysis

A Spherically Shielded Triphenylamine and Its Persistent Radical Cation - Schaub, Tobias A.; Mekelburg, Theresa; Dral, Pavlo O.; Miehlich, Matthias; Hampel, Frank; Meyer, Karsten; Kivala, Milan (Chemistry - A European Journal, 2020)
This work reports the design and synthesis of a sterically protected triphenylamine scaffold which undergoes one-electron oxidation to form an amine-centered radical cation of remarkable stability. Several structural adjustments were made to tame the inherent reactivity of the radical cation. First, the parent propeller-shaped triphenylamine was planarized with sterically demanding bridging units and, second, protecting groups were deployed to block the reactive positions. The efficiently shielded triphenylamine core can be reversibly oxidized at moderate potentials (+0.38 V, vs. Fc/Fc(+) in CH2Cl2). Spectroelectrochemistry and chemical oxidation studies were employed to monitor the evolution of characteristic photophysical features. To obtain a better understanding of the impact of one-electron oxidation on structural and electronic properties, joint experimental and computational studies were conducted, including X-ray structural analysis, electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. The sterically shielded radical cation combines various desirable attributes: A characteristic and unobstructed absorption in the visible region, high stability which enables storage for weeks without spectroscopically traceable degradation, and a reliable oxidation/re-reduction process due to effective screening of the planarized triphenylamine core from its environment.
CRIS-Team WoS Importer:2020-03-06

A square-planar ruthenium(II) complex with a low-spin configuration - Askevold, Bjorn; Khusniyarov, Marat; Herdtweck, Eberhardt; Meyer, Karsten; Schneider, Sven (Angewandte Chemie International Edition, 2010)
Ground-about: The ruthenium(II) complex [RuClN(CH CH PtBu ) ] (B) is obtained in high yield by the reaction of [RuCl HN(CH CH PtBu ) ] (A) with KOtBu. Complex B exhibits an unusual electronic low-spin (S=0) ground-state configuration. Comparison with Caulton's [RuClN(SiMe CH PtBu ) ] (ground state: S=1) shows that the ground-state spin multiplicity in these complexes is controlled by the N→Ru π-donor strength. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Assembly of Zinc‐Single‐Site‐Containing Silica Nanoparticles to Supraparticle Powders with Destructibility to Serve as Filler and Vulcanization Activator in Rubbers - Wenderoth, Sarah; Milana, Paola; Zimmermann, Thomas; Deues, Moritz; Oppmann, Maximilian; Prieschl, Johannes; Mostoni, Silvia; Scotti, Roberto; Wintzheimer, Susanne; Mandel, Karl (Particle & Particle Systems Characterization, 2024)
SECTIONSPDFPDFTOOLS SHARE Abstract The vulcanization process is widely used in industry for tire manufacturing. Therefore, zinc oxide is commonly utilized as an activator material, but unreacted zinc oxide remains in the final products and can be released into the environment with a significant impact. To reduce the amount of required zinc and to prevent leaching from tire material, zinc single site-containing silica fillers are interesting candidates. In these materials, zinc sites are anchored on the surface of silica nanoparticles through their complexation with functionalized aminosilanes. Based on these, a novel powder sample is prepared via spray-drying. The obtained supraparticles allow for a homogeneous distribution of the filler nanoparticles in the rubber matrix via their disintegration during the incorporation process. All synthesis steps are carried out in ethanol and water, respectively, at very mild temperatures to account for sustainability demands. As core of this study, the role of zinc ions and their amino-complexation in nanoparticle dispersion stability and in supraparticle formation during spray-drying is elucidated. Additionally, the superior performance of supraparticles as activator in rubber vulcanization is demonstrated. These show a higher curing efficiency, leading to lower curing time (−70%), higher torque values (+15%), and improved dynamic mechanical properties compared to the conventional ZnO activato
Keywords: morphology control; rubber nanocomposite; silica nanoparticles; spray-dried supraparticles; surface modification; zinc-activated vulcanization

Assigning Electronic States in Carbon Nanodots - Strauß, Volker; Kahnt, Axel; Zolnhofer, Eva; Meyer, Karsten; Maid, Harald; Placht, Christian; Bauer, Walter; Nacken, Thomas; Peukert, Wolfgang; Etschel, Sebastian; Halik, Marcus; Guldi, Dirk Michael (Advanced Functional Materials, 2016)
Luminescent carbon nanodots exhibit enormous potential to be used as functional building blocks in energy conversion devices. Their intrinsic heterogeneity, however, hinders a thorough characterization and subsequently their applicability. In this work, the spectroscopic and electrochemical properties of prototype carbon nanodots were thoroughly studied in solution. Spectro-electrochemical experiments revealed information on the spectral features of several oxidized and reduced species of our carbon nanodots. Therefore, these experiments were complemented with pulse radiolysis where the spectral signature of the one-electron oxidized and reduced forms were identified. Both, electrochemically and radiolytically reduced and oxidized products show high reactivity in solution which correlates with an open-shell character, detected by paramagnetic resonance spectroscopy. The herein presented studies help to understand the complex nature of carbon nanodots and serve to overcome difficulties in device fabrication.

A Stable Crystalline Triarylphosphine Oxide Radical Anion - Schaub, Tobias; Zolnhofer, Eva; Halter, Dominik; Shubina, Tatyana; Hampel, Frank; Meyer, Karsten; Kivala, Milan (Angewandte Chemie International Edition, 2016)
Triarylphosphine oxides (Ar3P=O) are being intensely studied as electron-accepting (n-type) materials. Despite the widespread application of these compounds as electron conductors, experimental data regarding the structural and electronic properties of their negatively charged states remain scarce owing to their propensity for follow-up chemistry. Herein, a carefully designed triarylphosphine oxide scaffold is disclosed that comprises sterically demanding spirofluorenyl moieties to shield the central phosphoryl (P=O) moiety. This compound undergoes chemical one-electron reduction to afford an exceptionally stable radical anion, which was isolated and characterized by X-ray crystallography for the very first time. The experimental data, corroborated by computational studies, shall allow for the construction of phosphine oxide materials with enhanced stability.
EAM Import::2019-03-13

A structurally characterised pair of dicobalt(III) peroxo/superoxo complexes with C2-symmetrical tetrapodal pentadentate amine ligands, and some reactivity en route - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2000)
Keywords: Cobalt; Peroxo complexes; N ligands; Superoxo complexes; Sulfito complexes

A Supraparticle-Based Five-Level-Identification Tag That Switches Information Upon Readout - Miller, Franziska; Wintzheimer, Susanne; Prieschl, Johannes; Strauss, Volker; Mandel, Karl (Advanced Optical Materials, 2020)
Product identification tags are of great importance in a globalized world with increasingly complex trading routes and networks. Beyond currently used coding strategies, such as QR codes, higher data density, flexible application as well as miniaturization and readout indication are longed for in the next generation of security tags. In this work, micron-sized supraparticles (SPs) with encoded information (ID) are produced that not only exhibit multiple initially covert identification levels but are also irreversibly marked as “read” upon readout. To achieve this, lanthanide doped CaF2 nanoparticles are assembled in various quantity-weighted ratios via spray-drying in presence of a broad-spectrum stealth fluorophore (StFl), yielding covert spectrally encoded ID-SPs. Using these as pigments, QR codes, initially dominated by the green fluorescence of the StFl, could be generated. Upon thermal energy input, these particle-based tags irreversibly switch to an activated state revealing not only multiple luminescent colors but also spectral IDs. This strategy provides the next generation of material-based security tags with a high data density and security level that switch information upon readout and can be, therefore, used as seal of quality.
CRIS-Team Scopus Importer:2020-12-25
Keywords: multilevel luminescence identification; rare earth doped nanoparticles; security tags; stealth fluorophores; supraparticles

Asymmetric cyclopropanation catalyzed by C2-symmetric bi(oxazolines) - Scheurer, Andreas; et al. (Tetrahedron Letters, 2000)
Keywords: Alkenes; Copper; Asymmetric reactions; Cyclopropanation; Copper compounds

A synthesis detour to planar-diastereoisomeric ferrocene derivatives around an unexpected rearrangement of ortho-lithiated Kagan's template [S(S)]-(p-tolylsulfinyl)ferrocene - Heinemann, Frank Wilhelm; et al. (Helvetica Chimica Acta, 2007)
Usually, ortho lithiation of Kagan's template 1 and quenching with electrophiles leads highly diastereoselectively to planar-chiral 1,2-disubstituted ferrocenes. Surprisingly, lithiation of 1 with lithium diisopropylamide (LDA) followed by addition of paraformaldehyde afforded regioisomer (+)-[S(S)]-[4-(2-hydroxyethyl)phenyl]sulfinyl)ferrocene (2), which was converted to (+)-[S(S)]-4-2-[(methylsulfonyl)oxy]ethyl)phenyl)sulfinylferrocene (3) (Scheme 1). The desired diastereoisomer (l)-1-(hydroxymethyl)-2-(p-tolylsulfinyl)ferrocene (5) in turn could also be obtained by ortho lithiation of 1 with LDA but by quenching with DMF to yield aldehyde 4 first, which then was reduced with NaBH4 to 5. Finally, target compound (l)-1-[(dimethylamino)methyl]-2-(p-tolylsulfinyl)ferrocene (6) was obtained by substitution of the OH group of 5 under mild conditions or directly by ortho lithiation of I with lithio-2,4,6-triisopropylbenzene (= 2,4,6-triisopropylphenyl)lithium; LTP) followed by quenching with N, N-dimethylmethyleneiminium chloride. At low temperatures, reaction of 1 with LDA leads, via the preferred diastereoisomeric transition state 'exo'-7 and under extrusion of a (diisopropylamine)lithium complex of type 8, in a highly selective manner, to diastereoisomeric ortho-lithiated chelate (l)-9 (Scheme 2). The reaction of I to 2 is explained by a rearrangement of (l)-9 to [S(S)][4-(lithiomethyl)phenyl]sulfinylferrocene 10, which is acid-catalyzed by coordinated diisopropylamine in complexes of type 8. This rearrangement is not observed if LTP is used as base or, in case LDA is applied, if the electrophile is sufficiently reactive at low temperatures.

A Terminal Iron Nitrilimine Complex: Accessing the Terminal Nitride through Diazo N−N Bond Cleavage - Aghazada, Sadig; Miehlich, Matthias; Messelberger, Julian; Heinemann, Frank Wilhelm; Munz, Dominik; Meyer, Karsten (Angewandte Chemie International Edition, 2019)
A novel method for the N−N bond cleavage of trimethylsilyl diazomethane is reported for the synthesis of terminal nitride complexes. The lithium salt of trimethylsilyl diazomethane was used to generate a rare terminal nitrilimine transition metal complex with partially occupied d-orbitals. This iron complex 2 was characterized by CHN combustion analysis, 1H and 13C NMR spectroscopic analysis, single-crystal X-ray crystallography, SQUID magnetometry, 57Fe Mössbauer spectroscopy, and computational analysis. The combined results suggest a high-spin d 6 (S=2) electronic configuration and an allenic structure of the nitrilimine ligand. Reduction of 2 results in release of the nitrilimine ligand and formation of the iron(I) complex 3, which was characterized by CHN combustion analysis, 1H NMR spectroscopic analysis, and single-crystal X-ray crystallography. Treatment of 2 with fluoride salts quantitatively yields the diamagnetic FeIV nitride complex 4, with concomitant formation of cyanide and trimethylsilyl fluoride through N−N bond cleavage.
CRIS-Team Scopus Importer:2019-11-15
Keywords: diazo compounds; iron; N-heterocyclic carbenes; N−N activation; terminal nitrides

A Tetramethylplatinum(IV) Complex with 1,1 '-Bis(diphenylphosphanyl)ferrocene Ligands: Reaction with Trifluoroacetic Acid - Shahsavari, Hamid R.; Rashidi, Mehdi; Nabavizadeh, S. Masoud; Habibzadeh, Sepideh; Heinemann, Frank Wilhelm (European Journal of Inorganic Chemistry, 2009)
A new tetramethylplatinum(IV) complex [PtMe4(dppf)] [2; dppf = 1,1'-bis(diphenylphosphanyl)ferrocene], as the first platinum(IV) complex to contain a chelating dppf ligand, was prepared by the reaction of the known dimeric tetramethylplatinum(IV) complex cis, cis-[Me4Pt(mu-SMe2)(2)PtMe4] (1) with the biphosphane ligand dppf (2 equiv.) at room temperature by replacement of the SMe2 ligands with the P ligating atoms of dppf. The single-crystal X-ray structure of complex 2 revealed that the dppf chelating ligand is arranged close to the "synperiplanar-eclipsed" conformation, with a Cp(centroid)center dot center dot center dot Fe center dot center dot center dot Cp(centroid) twist angle of 17.6 degrees and a dppf bite angle, P1-Pt1-P2, of 95.77(3)degrees. This is in contrast to the usually pref erred "synclinal-staggered" conformation, in which the Cp(centroid)center dot center dot center dot Fe center dot center dot center dot Cp(centroid) twist angle is close to 36 degrees as found in Pt-II complexes with chelating dppf ligands, like for example [PtMe2(dppf)] exhibiting a dppf bite angle close to 100 degrees. When complex 2 was treated with the strong acid CF3COOH (1 equiv.) first evolution of methane was observed, followed by a C-C coupling reaction to give ethane and the methylplatinum(II) complex [PtMe(OCOCF3)(dppf)] (3). The reaction of complex 2 with the nucleophile HgCl2 (1 equiv.) similarly gave MeHgCl, ethane, and the methylplatinum(II) complex [PtMeCl(dppf)] (11). The structure of complex 3 was also determined by X-ray crystallography. The geometry around the platinum center is best described as distorted square-planar and the dppf is arranged in the usually preferred "synclinal-staggered" conformation. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Keywords: Platinum; Metallocenes; P ligands; Conformation analysis

A tetraphosphane imine ligand which enforces square-pyramidal coordination - Zimmermann, C.; Heinemann, Frank Wilhelm; Grohmann, Andreas (European Journal of Inorganic Chemistry, 2005)
Keywords: Cobalt; Chelates; Phosphane ligands; Nickel; Tetrapodal pentadentate ligand

A theoretical mechanistic study of [K ⊂ [2.2.2]]+ enantiomerization - Balovic, Jelena; Cocic, Dusan; Dordevic, Sladana; Radenkovic, Slavko; van Eldik, Rudi; Puchta, Ralph (Journal of Physical Organic Chemistry, 2021)
Density functional calculations at three different levels of theory (B3LYP/LANL2DZp, B3LYP-GD3/LANL2DZp, and ωB97XD/def2tzvp) were applied to different conformers of the Lehn-type macrobicyclic polyether cryptate complex [K ⊂ [2.2.2]]+ to construct the enantiomerization pathway and to compute the energy barrier for the change in symmetry. Changes in the conformation of the investigated complex are discussed in terms of energy and geometric criteria, where changes in the structures follow a trend of activation energies prohibiting the achiral pathways. The investigated D3-symmetric cryptate [K ⊂ [2.2.2]]+ shows enantiomerization through an all chiral five step pathway with two local minima (C2 and C2′) and three C1 transition states ending in the D3′-symmetric cryptate [K ⊂ [2.2.2]]+, the mirror image of the starting structure. The potential achiral transition states are higher order saddle points with a minimum twice as high in energy as an all-chiral path. This study unambiguously accounts for Lehn's NMR data showing fluxionality of the studied complex. The obtained results were further rationalized by means of energy decomposition analysis (EDA) and natural bond orbital (NBO) calculations performed for the metal cation and the host in its different conformations.
CRIS-Team Scopus Importer:2021-10-08
Keywords: cryptand; DFT study; EDA; enantiomerization; NBO

A three-coordinate copper(II) amide from reductive cleavage of a nitrosamine - Melzer, Marie M.; Mossin, Susanne; Dai, Xuliang; Bartell, Ashley M.; Kapoor, Pooja; Meyer, Karsten; Warren, Timothy H. (Angewandte Chemie International Edition, 2010)
A NO-velty: A copper(1) β-diketiminate activates the nitrosamine Ph NNO to give a rare, three-coordinate copper(II) amide, [(Me NN)Cu-NPh ]. Reaction of this amide with NO returns Ph NNO as well as a mixed-valence species with NOfunctionalized β-diketiminate ligands (see scheme; Cu light blue, N dark blue, O red). Thus, both the cleavage and formation of R N-NO bonds may take place at a common copper center. (Figure Presented) © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Atomic Layer Deposition from Dissolved Precursors - Wu, Yanlin; Döhler, Dirk; Barr, Maissa K. S.; Oks, Elina; Wolf, Marc; Santinacci, Lionel; Bachmann, Julien (Nano Letters, 2015)
We establish a novel thin film deposition technique by transferring the principles of atomic layer deposition (ALD) known with gaseous precursors toward precursors dissolved in a liquid. An established ALD reaction behaves similarly when performed from solutions. "Solution ALD" (sALD) can coat deep pores in a conformal manner. sALD offers novel opportunities by overcoming the need for volatile and thermally robust precursors. We establish a MgO sALD procedure based on the hydrolysis of a Grignard reagen
Keywords: Atomic layer deposition; LBL; SEAR; thin films; magnesium oxide; microfluidic

Atomic Layer Deposition of i-Sb2S3/p-NiO Thin Layers into Anodic Alumina Membranes for Photoelectrochemical Water Splitting - Barr, M. K.S.; Assaud, Loic; Wu, Yanlin; Bachmann, Julien; Santinacci, L. (ECS Transactions, 2015)
A nanostructured photoelectrode was fabricated by atomic layer deposition (ALD) of NiO and Sb2S3 in nanoporous alumina. The fabrication, i.e. the successive ALD of NiO and Sb2S3, and the characterization of the arrays of coaxial NiO/Sb2S3 junction by electron microscopies are first reported. The optical and photoelectrochemical preliminary testing of the combination of such extremely thin absorber, Sb2S3, with a p-type semiconductor, NiO, are proposed in a second part. Although the photoconversion performances should be improved, the present work demonstrates validity of the concept.
EAM Import::2019-03-13

A Trinuclear [NiFe] Cluster Exhibiting Structural and Functional Key Features of [NiFe] Hydrogenases - Heinemann, Frank Wilhelm; et al. (Angewandte Chemie International Edition, 2004)
Charged but not changed: A trinuclear [NiFe] cluster combining the key structural features and reactivity of [NiFe] hydrogenases has been prepared (structure shown). Protons oxidize this cluster to its cation, which has the same structural parameters as the neutral form and therefore shows an important key feature of many oxidoreductases: structural rigidity during the electron-transfer processes.
UnivIS-Import:2017-03-24:Pub.2004.forsch.sonder.sfb583.atrinu
Keywords: Bioinorganic chemistry; Hydrogenases; Iron; Nickel; Redox chemistry

Aufklärung von Reaktionswegen bei der Dithiocarboxylierung mittels Röntgenkristallstrukturanalyse - Heinemann, Frank Wilhelm; Hartung, H; Dölling, W. (Gemeinsame Tagung der Arbeitsgemeinschaft Kristallographie (der DMG, DPG und GDCh) und Vereinigung für Kristallographie 1991 München, 1991)

A valence tautomeric cobalt-dioxolene complex with an anchoring group for prospective chemical grafting to metal oxides - Mörtel, Max; Seller, Michael; Heinemann, Frank Wilhelm; Khusniyarov, Marat (Dalton Transactions, 2020)
Here, we synthesized a valence tautomeric cobalt-dioxolene complex featuring a protected anchoring group. At room temperature, the complex reveals a nearly pure low-spin-Co(III)-catecholate state in the solid state, but a nearly pure high-spin-Co(II)-semiquinonate state in toluene solution. Thermal switchability of the complex in solution and in the solid state is investigated.
CRIS-Team WoS Importer:2021-01-29

A Vanadium Methylidene - Senthil, Shuruthi; Fehn, Dominik; Gau, Michael R.; Bacon, Alexandra M.; Carroll, Patrick J.; Meyer, Karsten; Mindiola, Daniel J. (Journal of the American Chemical Society, 2024)
Examples of stable 3d transition metal methylidene complexes are extremely rare. Here we report an isolable and stable vanadium methylidene complex, [(PNP)V(=NAr)(=CH2)] (PNP = N[2-PiPr2-4-methylphenyl]−, Ar = 2,6-iPr2C6H3), via H atom transfer (HAT) from [(PNP)V(NHAr)(CH3)] or [(PNP)V(=NAr)(CH3)] using two or one equivalents of the TEMPO radical (TEMPO = (2,2,6,6-tetramethylpiperidin-1-yl)oxyl), respectively. Alternatively, the vanadium methylidene moiety can also be formed via the treatment of transient [(PNP)V=NAr] with the Wittig reagent, H2CPPh3. Structural and spectroscopic analysis, including 13C enriched labeling of the methylidene ligand, unequivocally confirmed the terminal nature of a rare 3d methylidene complex, featuring a V=CH2 bond distance of 1.908(2) Å and a highly downfield 13C NMR spectral shift at 298 ppm. In the absence of the ylide, intermediate [(PNP)V=NAr] activates dinitrogen to form an end-on bridging N2 complex, [(PNP)V(=NAr)]2(μ2-η1:η1-N2), having a singlet ground state. Complex [(PNP)V(=NAr)(=CH2)] reacts with H3COTf to form [(PNP)V(=NAr)(OTf)], accompanied by the release of ethylene as evidenced by 1H NMR spectroscopy, and reactivity studies suggest a β-hydride elimination pathway.
CRIS-Team Scopus Importer:2024-06-14

Azole-based diarylethenes as the next step towards advanced photochromic materials - Lvov, Andrey G.; Khusniyarov, Marat; Shirinian, Valerii Z. (Journal of Photochemistry and Photobiology C-Photochemistry Reviews, 2018)
Keywords: Photochromism; Thiazole; Imidazole; Oxazole; Diarylethene

A Zwitterionic Heterobimetallic Gold–Iron Complex Supported by Bis(N-Heterocyclic Imine)Silyliumylidene - Hanusch, Franziska; Munz, Dominik; Sutter, Jörg; Meyer, Karsten; Inoue, Shigeyoshi (Angewandte Chemie International Edition, 2021)
The facile synthesis of the first bis-N-heterocyclic imine-stabilized chlorosilyliumylidene 1 is reported. Remarkably, consecutive reaction of 1 with PPh3AuCl and K2Fe(CO)4 gives rise to the unique heterobimetallic complex 1,2-(MesNHI)2-C2H4-ClSiAuFe(CO)4 (4). The overall neutral complex 4 bears an unusual linear Si−Au−Fe structure and a rare anagostic interaction between the d10-configured gold atom and a CH bond of the mesityl ligand. According to the computational analysis and 57Fe Mössbauer spectroscopy, the formal Fe-oxidation state remains at −II. Thus, the electronic structure of 4 is best described as an overall neutral—yet zwitterionic—heterobimetallic “Si(II)+-Au(I)+-Fe(-II)2−”-silyliumylidene complex, derived from double anion exchange. The computational analysis indicates strong hyperconjugative back donation from the gold(I) atom to the silyliumylidene ligand.
CRIS-Team Scopus Importer:2021-10-01
Keywords: anagostic interactions; gold; iron; silicon; zwitterionic complexes

Back Cover: Energy Storage in Strained Organic Molecules: (Spectro)Electrochemical Characterization of Norbornadiene and Quadricyclane (ChemSusChem 12/2016) - Brummel, Olaf; Besold, Daniel; Döpper, Tibor; Wu, Yanlin; Bochmann, Sebastian; Lazzari, Federica; Waidhas, Fabian; Bauer, Udo; Bachmann, Philipp; Papp, Christian; Steinrück, Hans-Peter; Görling, Andreas; et al. (ChemSusChem, 2016)
Keywords: infrared spectroscopy; norbornadiene; quadricyclane; spectroelectrochemistry; voltammetry

Beneficial effects of liquid crystalline phases in solid-state dye-sensitized solar cells - Costa, Ruben Dario; Werner, Fabian; Wang, Xinjiao; Grönninger, Philipp; Feihl, Sebastian; Kohler, Florian; Wasserscheid, Peter; Hibler, Susanne; Beranek, Radim; Meyer, Karsten; Guldi, Dirk Michael (Advanced Energy Materials, 2013)
Two novel double-alkyl functionalized imidazolium ionic liquid crystals have successfully been utilized to demonstrate the benefits of the liquid crystalline phase on the ssDSSC performance. In particular, a good balance between dye regeneration and hole transport is only realized in the liquid crystalline phase. Devices that employ a single component ionic liquid based electrolyte show a remarkably stable efficiency during 1000 h under outdoor operation temperature conditions and 1 sun illumination. Two novel double-alkyl functionalized imidazolium ionic liquid crystals have successfully been utilized to demonstrate the benefits of the liquid crystalline phase on the ssDSSC performance. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Benzene-1,4-Di(dithiocarboxylate) Linker-Based Coordination Polymers of Mn2+, Zn2+, and Mixed-Valence Fe2+/3+ - Aust, Margit; Schönherr, Marina I.; Halter, Dominik P.; Schröck, Lena; Pickl, Thomas; Deger, Simon N.; Hussain, Mian Z.; Jentys, Andreas; Bühler, Raphael; Zhang, Zihan; Meyer, Karsten; Kuhl, Matthias; et al. (Inorganic Chemistry, 2024)
Three new coordination polymers (CPs) constructed from the linker 1,4-di(dithiocarboxylate) (BDDTC2-)─the sulfur-analog of 1,4-benzenedicarboxylate (BDC2-)─together with Mn-, Zn-, and Fe-based inorganic SBUs are reported with description of their structural and electronic properties. Single-crystal X-ray diffraction revealed structural diversity ranging from one-dimensional chains in [Mn(BDDTC)(DMF)2] (1) to two-dimensional (2D) honeycomb sheets observed for [Zn2(BDDTC)3][Zn(DMF)5(H2O)] (2). Gas adsorption experiments confirmed a 3D porous structure for the mixed-valent material [Fe2(BDDTC)2(OH)] (3). 3 contains a 1:1 ratio of Fe2+/3+ ions, as evidenced by 57Fe Mössbauer, X-band EPR, and X-ray absorption spectroscopy. Its empirical formula was established by elemental analysis, thermal gravimetric analysis, infrared vibrational spectroscopy, and X-ray absorption spectroscopy in lieu of elusive single-crystal X-ray diffraction data. In contrast to the Mn- and Zn-based compounds 1 and 2, the Fe2+/3+ CP 3 showed remarkably high electrical conductivity of 5 × 10-3 S cm-1 (according to van der Pauw measurements), which is within the range of semiconducting materials. Overall, our study confirms that sulfur derivatives of typical carboxylate linkers (e.g., BDC) are suitable for the construction of electrically conducting CPs, due to acceptedly higher covalency in metal-ligand bonding compared to the electrically insulating carboxylate CPs or metal-organic frameworks. At the same time, the direct comparison between insulating CPs 1 and 2 with CP 3 emphasizes that the electronic structure of the metal is likewise a crucial aspect to construct electrically conductive materials.
CRIS-Team Scopus Importer:2024-01-19

Between imide, imidyl and nitrene - an imido iron complex in two oxidation states - Reith, Sascha; Demeshko, Serhiy; Battistella, Beatrice; Reckziegel, Alexander; Schneider, Christian; Stoy, Andreas; Lichtenberg, Crispin; Meyer, Franc; Munz, Dominik; Werncke, C. Gunnar (Chemical Science, 2022)
Imidyl and nitrene metal species play an important role in the N-functionalisation of unreactive C-H bonds as well as the aziridination of olefines. We report on the synthesis of the trigonal imido iron complexes [Fe(NMes)L2]0,− (L = -NDippSiMe3); Dipp = 2,6-diisopropyl-phenyl; Mes = (2,4,6-trimethylphenyl) via reaction of mesityl azide (MesN3) with the linear iron precursors [FeL2]0,−. UV-vis-, EPR-, 57Fe Mössbauer spectroscopy, magnetometry, and computational methods suggest for the reduced form an electronic structure as a ferromagnetically coupled iron(ii) imidyl radical, whereas oxidation leads to mixed iron(iii) imidyl and electrophilic iron(ii) nitrene character. Reactivity studies show that both complexes are capable of H atom abstraction from C-H bonds. Further, the reduced form [Fe(NMes)L2]− reacts nucleophilically with CS2 by inserting into the imido iron bond, as well as electrophilically with CO under nitrene transfer. The neutral [Fe(NMes)L2] complex shows enhanced electrophilic behavior as evidenced by nitrene transfer to a phosphine, yet in combination with an overall reduced reactivity.
CRIS-Team Scopus Importer:2022-07-08

Bicyclic diironcryptates with mobile guest cations: A new class of solid ionic conductors - Puchta, Ralph; Roling, Bernhard; Scheurer, Andreas; Weiskopf, Verena; Hampel, Frank; van Eikema Hommes, Nico; Hummel, Hans-Ulrich (Solid State Ionics, 2008)
Polycrystalline bicyclic diironcryptates with different mobile guest cations were synthesized and characterized by XRD analysis, IR spectroscopy, FAB-mass spectroscopy, elemental analysis, electrical conductivity spectroscopy and ion exchange experiments. We find strong indication that the guest cations exhibit a long-range mobility and that their mobility is governed by their size relative to the size of the cryptand molecules. On the other hand, the valence of the guest cations seems to play a minor role for the mobility. These results are discussed in comparison to the properties of conventional solid cationic conductors. (c) 2008 Elsevier B.V. All rights reserved.
Keywords: supramolecular chemistry; metallacryptates; cationic conductor; conductivity spectroscopy; ion exchange

Bidirectional photoswitching of magnetic properties at room temperature: ligand-driven light-induced valence tautomerism - Witt, Alexander; Heinemann, Frank Wilhelm; Khusniyarov, Marat (Chemical Science, 2015)
Valence tautomeric (VT) metal complexes are highly promising bistable molecular compounds for applications as molecular switches in molecular electronics and spintronics. Although VT species can be switched with light, the photoswitching in all reported systems requires very low temperatures (usually below 20 K) because photoinduced states are highly unstable at room temperature. The thermal instability hinders any practical application of these complexes in genuine devices. In this report, for the first time we demonstrate photoswitching of VT species and associated magnetic properties at room temperature. The bidirectional photoswitching in solution is due to cis-trans photoisomerizable 4-styrylpyridine ligands deliberately integrated into cobalt dioxolene molecular complexes. The novel type of photoswitching has been coined Ligand-Driven Light-Induced Valence Tautomerism (LD-LIVT). The photoconversion of VT states of 28% has been achieved in solution at room temperature. The photoinduced states show extraordinary thermal stability for hours at room temperature, as compared to common nanoseconds reported previously. The switching proceeds at molecular level with the effective photoswitching rate of 3 x 10(13) molecules per s under our conditions. Consequently, this work may open new horizons in applications of molecular switches based on VT metal complexes in molecular devices functioning at room temperature.

Bifurcated N-H•••S hydrogen bridges resulting in strong stabilization of nitrogenase model complexes - Heinemann, Frank Wilhelm; Sellmann, Dieter; Blum, D.; Engl, K.; Gottschalk-Gaudig, Torsten (Lecture Notes and Poster Abstracts P15, 2001)

Bimetallic μ-cyanoimide complexes prepared by NCN group transfer - Mindiola, Daniel; Tsai, Yi-Chou; Hara, Ryuichiro; Chen, Qinghao; Meyer, Karsten; Cummins, Christopher C. (Chemical Communications, 2001)
A cyanoimide [NCN] transfer reagent has been developed and applied to the synthesis of the μ-NCN systems (μ ;η ,η -NCN) M[N(R)Ar] (Ar = C H Me -3,5; M = V or U, R = Bu ; M = Mo, R = Pr ).

Binary Alkali Metal Compounds with the Zintl Anions [Ge9]4- and [Sn9]4- - von Schnering, H. G.; Baitinger, M.; Bolle, U.; Carillo-Cabrera, W.; Curda, J.; Grin, Y.; Heinemann, Frank Wilhelm; Llanos, J.; Peters, Kim; Schmeding, A.; Somer, M. (Zeitschrift für Anorganische und Allgemeine Chemie, 1997)

Binding H2, N2, H-, and BH3 to transition-metal sulfur sites: synthesis and properties of [RuL(PR3)(N2Me2S2)] Complexes (L=eta2-H2, H-, BH3; R=Cy, iPr). - Heinemann, Frank Wilhelm; et al. (Chemistry - A European Journal, 2004)
The reactions of [Ru(N(2))(PR(3))('N(2)Me(2)S(2)')] ['N(2)Me(2)S(2)'=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)] [1 a (R=iPr), 1 b (R=Cy)] and [micro-N(2)[Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')](2)] (1 c) with H(2), NaBH(4), and NBu(4)BH(4), intended to reduce the N(2) ligands, led to substitution of N(2) and formation of the new complexes [Ru(H(2))(PR(3))('N(2)Me(2)S(2)')] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH(3))(PR(3))('N(2)Me(2)S(2)')] [3 a (R=iPr), 3 b (R=Cy)], and [Ru(H)(PR(3))('N(2)Me(2)S(2)')](-) [4 a (R=iPr), 4 b (R=Cy)]. The BH(3) and hydride complexes 3 a, 3 b, 4 a, and 4 b were obtained subsequently by rational synthesis from 1 a or 1 b and BH(3).THF or LiBEt(3)H. The primary step in all reactions probably is the dissociation of N(2) from the N(2) complexes to give coordinatively unsaturated [Ru(PR(3))('N(2)Me(2)S(2)')] fragments that add H(2), BH(4) (-), BH(3), or H(-). All complexes were completely characterized by elemental analysis and common spectroscopic methods. The molecular structures of [Ru(H(2))(PR(3))('N(2)Me(2)S(2)')] [2 a (R=iPr), 2 b (R=Cy)], [Ru(BH(3))(PiPr(3))('N(2)Me(2)S(2)')] (3 a), [Li(THF)(2)][Ru(H)(PiPr(3))('N(2)Me(2)S(2)')] ([Li(THF)(2)]-4 a), and NBu(4)[Ru(H)(PCy(3))('N(2)Me(2)S(2)')] (NBu(4)-4 b) were determined by X-ray crystal structure analysis. Measurements of the NMR relaxation time T(1) corroborated the eta(2) bonding mode of the H(2) ligands in 2 a (T(1)=35 ms) and 2 b (T(1)=21 ms). The H,D coupling constants of the analogous HD complexes HD-2 a ((1)J(H,D)=26.0 Hz) and HD-2 b ((1)J(H,D)=25.9 Hz) enabled calculation of the H–D distances, which agreed with the values found by X-ray crystal structure analysis (2 a: 92 pm (X-ray) versus 98 pm (calculated), 2 b: 99 versus 98 pm). The BH(3) entities in 3 a and 3 b bind to one thiolate donor of the [Ru(PR(3))('N(2)Me(2)S(2)')] fragment and through a B-H-Ru bond to the Ru center. The hydride complex anions 4 a and 4 b are extremely Brønsted basic and are instantaneously protonated to give the eta(2)-H(2) complexes 2 a and 2 b.

Binding N2, N2H2, N2H4, and NH3 to transition-metal sulfur sites: modeling potential intermediates of biological N2 fixation. - Heinemann, Frank Wilhelm; et al. (Chemistry - A European Journal, 2004)
In the quest for low-molecular-weight metal sulfur complexes that bind nitrogenase-relevant small molecules and can serve as model complexes for nitrogenase, compounds with the [Ru(PiPr(3))('N(2)Me(2)S(2)')] fragment were found ('N(2)Me(2)S(2)'(2-)=1,2-ethanediamine-N,N'-dimethyl-N,N'-bis(2-benzenethiolate)(2-)). This fragment enabled the synthesis of a first series of chiral metal sulfur complexes, [Ru(L)(PiPr(3))('N(2)Me(2)S(2)')] with L=N(2), N(2)H(2), N(2)H(4), and NH(3), that meet the biological constraint of forming under mild conditions. The reaction of [Ru(NCCH(3))(PiPr(3))('N(2)Me(2)S(2)')] (1) with NH(3) gave the ammonia complex [Ru(NH(3))(PiPr(3))('N(2)Me(2)S(2)')] (4), which readily exchanged NH(3) for N(2) to yield the mononuclear dinitrogen complex [Ru(N(2))(PiPr(3))('N(2)Me(2)S(2)')] (2) in almost quantitative yield. Complex 2, obtained by this new efficient synthesis, was the starting material for the synthesis of dinuclear (R,R)- and (S,S)-[micro-N(2)[Ru(PiPr(3))('N(2)Me(2)S(2)')](2)] ((R,R)-/(S,S)-3). (Both 2 and 3 have been reported previously.) The as-yet inexplicable behavior of complex 3 to form also the R,S isomer in solution has been revealed by DFT calculations and (2)D NMR spectroscopy studies. The reaction of 1 or 2 with anhydrous hydrazine yielded the hydrazine complex [Ru(N(2)H(4))(PiPr(3))('N(2)Me(2)S(2)')] (6), which is a highly reactive intermediate. Disproportionation of 6 resulted in the formation of mononuclear diazene complexes, the ammonia complex 4, and finally the dinuclear diazene complex [micro-N(2)H(2)[Ru(PiPr(3))('N(2)Me(2)S(2)')](2)] (5). Dinuclear complex 5 could also be obtained directly in an independent synthesis from 1 and N(2)H(2), which was generated in situ by acidolysis of K(2)N(2)(CO(2))(2). Treatment of 6 with CH(2)Cl(2), however, formed a chloromethylated diazene species [[Ru(PiPr(3))('N(2)Me(2)S(2)')]-micro-N(2)H(2)[Ru(Cl)('N(2)Me(2)S(2)CH(2)Cl')]] (9) ('N(2)Me(2)S(2)CH(2)Cl'(2-) =1,2-ethanediamine-N,N'-dimethyl-N-(2-benzenethiolate)(1-)-N'-(2-benzenechloromethylthioether)(1-)]. The molecular structures of 4, 5, and 9 were determined by X-ray crystal structure analysis, and the labile N(2)H(4) complex 6 was characterized by NMR spectroscopy.

Binding N_2_, N_2_H_2_, N_2_H_4_ and NH_3_ to Transition Metal Sulfur Sites: Modeling Potential Intermediates of Biological N_2_ Fixation - Sellmann, Dieter; Kisch, Horst; Hille, Andreas; Rösler, Annette; Heinemann, Frank Wilhelm; Moll, Matthias; Brehm, Georg; Reiher, Markus; Heß, Bernd Artur; Bauer, W. (Chemistry - A European Journal, 2003)
UnivIS-Import:2017-03-24:Pub.2003.forsch.sonder.sfb583.bindin

Biological activity of bis(pyrazolylpyridine) and terpiridine Os(II) complexes in the presence of biocompatible ionic liquids - Petrovic, Angelina Z.; Cocic, Dusan C.; Bockfeld, Dirk; Zivanovic, Marko; Milivojevic, Nevena; Virijevic, Katarina; Jankovic, Nenad; Scheurer, Andreas; Vranes, Milan; Bogojeski, Jovana V. (Inorganic Chemistry Frontiers, 2021)
Within this paper is presented the synthesis and structural characterization of three newly synthesized osmium(ii) complexes Os1-3, with the chemical formula [(OsLCl2H2O)-L-II], [L = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine (for Os1), 2,6-bis(5-tert-butyl-1-methyl-1H-pyrazol-3-yl)pyridine (for Os2) or 2,2 ':6 ',2 ''-terpyridine (for Os3)]. Single crystal X-ray analysis of a DMSO adduct of complex Os1 was performed. Kinetics of substitution reactions of examined Os1-3 complexes with biomolecules 5-GMP, l-Met, and GSH were followed in the presence and absence of different biocompatible ionic liquids. Binding properties of the examined complexes to biologically important molecules, CT-DNA and HSA, were investigated using UV-Vis spectrophotometry, fluorescence spectroscopy, and gel electrophoresis. Interactions with CT-DNA were performed both in the absence and presence of biocompatible ionic liquids. To locate the binding site and possible binding mode of the examined complexes to CT-DNA and HSA, fluorescence competition experiments with site-markers were performed. To better understand these interactions and obtain detailed binding information of the examined complexes with CT-DNA, and HSA, molecular docking studies and fluorescence resonance energy transfer (FRET) were performed. In vitro cytotoxicity and redox status experiments on three cancer cell lines and on one healthy cell line were performed to elucidate the possible molecular mechanisms of investigated Os1-3 complexes.
CRIS-Team WoS Importer:2021-05-21

Biomimetic [2Fe-2S] Clusters with Extensively Delocalized Mixed-Valence Iron Centers - Yao, Shenglai; Meier, Florian; Lindenmaier, Nils; Rudolph, Robert; Blom, Burgert; Adelhardt, Mario; Sutter, Jörg; Mebs, Stefan; Haumann, Michael; Meyer, Karsten; Kaupp, Martin; Driess, Matthias (Angewandte Chemie International Edition, 2015)
A complete series of biomimetic [2Fe-2S] clusters, [((LFe)-Fe-Dep)(2)(mu-S)(2)] (3, L(De)p = CH[CMeN(2,6-Et2C6H3)](2)), [((LFe)-Fe-Dep)(2)(mu-S)(2)K] (4), [(L(De)pFe)(2)(mu-S)(2)][Bu4N] (5, Bu=n-butyl), and [((LFe)-Fe-Dep)(2)(mu-S)(2)K-2] (6), could be synthesized and characterized. The all-ferric [2Fe-2S] cluster 3 is readily accessible through the reaction of [((LFe)-Fe-Dep)(2)(mu-H)(2)] (2) with elemental sulfur. The chemical reduction of 3 with one molar equivalent of elemental potassium affords the contact ion pair K+[2Fe-2S](-) (4) as a one-dimensional coordination polymer, which in turn reacts with [Bu4N] Cl to afford the separate ion pair [Bu4N](+)[2Fe-2S](-) (5). Further reduction of 4 with potassium furnishes the super-reduced all-ferrous [2Fe-2S] cluster 6. Remarkably, complexes 4 and 5 are [2Fe-2S] clusters with extensively delocalized Fe2+Fe3+ pairs as evidenced by Fe-57 Mossbauer, X-ray absorption and emission spectroscopy (XAS, XES) and in accordance with DFT calculations.
Keywords: iron; mixed-valence compounds; Rieske clusters; sulfur; beta-diketiminato ligands

Bis(3,5-dimethyl-4-vinylpyrazol-1-yl)acetic acid: A new heteroscorpionate building block for copolymers that mimic the 2-His-1-carboxylate facial triad - Türkoglu, Gazi; Ulldemolins, Cristina Pubill; Müller, Rainer; Hübner, Eike; Heinemann, Frank Wilhelm; Wolf, Marion; Burzlaff, Nicolai (European Journal of Inorganic Chemistry, 2010)
The new N,N,O ligand bis(3,5-dimethyl-4-vinylpyrazol-l-yl)-acetic acid. (Hbdmvpza) (4) suitable for copolymerisation was synthesised in a multi-step synthesis starting from bis(3,5-dimethylpyrazol-l-yl)methane (1). The κ -N,N,O facial coordination behaviour of 4 was verified by synthesis and characterisation of the tricarbonyl compounds [Mn(bdmvpza)(CO) ] (5) and [Re(bdmvpza)(CO) ] (6), the ruthenium bisphosphane complex [Ru(bdmvpza)Cl(PPh ) ] (7), as well as the complex [Cu(bdmvpza) ] (8). Copolymerisation of 4 with methyl methacrylate (MMA) or ethylene glycol dimethacrylate (EGDMA) led to solid phases P1a, P1b and P2 with different amounts of incorporated ligand 4. Furthermore, a homopolymer H1 of ligand 4 was successfully synthesised. Copolymer-bound manganese and rhenium tricarbonyl complexes P1a-Mn, P1a-Re, P2-Mn and P2-Re have been obtained by reaction of P1a and P2 with the metal precursors [MnBr(CO) ] and [ReBr(CO) ], respectively. The κ -N,N,O coordination of the manganese and rhenium centres was verified by IR spectroscopy and the amount of incorporated metal complex was determined by AAS or ICP-AES measurements. Treatment of the deprotonated copolymer P1a or P2 with copper(II) or iron(II) led to polymers P1a-Cu, P1a-Fe and P2-Fe. A bathochromic shift in the UV spectrum of P1a-Cu compared to the absorption maximum of the homogeneous complex 8 by 64 nm indicates copper centres with one ligand moiety bound only. AAS analysis of P1a-Fe and P2-Fe show that up to 64% of the ligand sites can be accessed with iron(II). Furthermore, two 2-oxocarboxylato complexes [Ru(bdmvpza)(BF)(PPh )] (9) (BF = benzoylformato) and [Ru(bdmvpza)(NOG)(PPh )] (10) (NOG = N-oxalylglycine) have been synthesised that mimic the shape of the active sites of 2-oxoglutarate dependent iron oxygenases. The successful copolymerisation of 9 and 10 with EGDMA was proven, by UV spectros py. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, We heim.

Bis(imidazolium)-1,3-diphosphete-diide: A Building Block for FeC2P2 Complexes and Clusters - Scharnhölz, Moritz Theodor; Coburger, Peter; Gravogl, Lisa; Klose, Daniel; Gamboa-Carballo, Juan José; Le Corre, Grégoire; Bösken, Jonas; Schweinzer, Clara; Thöny, Debora; Li, Zhongshu; Meyer, Karsten; Grützmacher, Hansjörg (Angewandte Chemie International Edition, 2022)
Reaction of the 6π-electron aromatic four-membered heterocycle (IPr)2C2P2 (1) (IPr=1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene) with [Fe2CO9] gives the neutral iron tricarbonyl complex [Fe(CO)3-η3-(IPr)2C2P2] (2). Oxidation with two equivalents of the ferrocenium salt, [Fe(Cp)2](BArF24), affords the dicationic tricarbonyl complex [Fe(CO)3-η4-(IPr)2C2P2](BArF24)2 (4). The one-electron oxidation proceeds under concomitant loss of one CO ligand to give the paramagnetic dicarbonyl radical cation complex [Fe(CO)2-η4-(IPr)2C2P2](BArF24) (5). Reduction of 5 allows the preparation of the neutral dicarbonyl complex [Fe(CO)2-η4-(IPr)2C2P2] (6). An analysis by various spectroscopic techniques (57Fe Mössbauer, EPR) combined with DFT calculations gives insight into differences of the electronic structure within the members of this unique series of iron carbonyl complexes, which can be either described as electron precise or Wade–Mingos clusters.
CRIS-Team Scopus Importer:2022-07-22
Keywords: Cluster Compounds; Density Functional Calculations; Donor–Acceptor Systems; Iron; Phosphorus

Bis(ny4-cycloocta-1,5-diene)rhodium (I) trifluoromethanesulfonate - Dahlenburg, Lutz; Osthoff, Nils; Heinemann, Frank Wilhelm (Acta Crystallographica Section E: Structure Reports Online, 2001)

Bis-polyethylene glycol-functionalized imidazolium ionic liquids: A multi-method approach towards bulk and surface properties - Seidl, Vera; Bosch, Michael; Paap, Ulrike; Livraghi, Mattia; Zhai, Ziwen; Wick, Christian; Koller, Thomas Manfred; Wasserscheid, Peter; Maier, Florian; Smith, Ana-Suncana; Bachmann, Julien; Steinrück, Hans-Peter; et al. (Journal of Ionic Liquids, 2022)
Adding to the versatile class of ionic liquids, we report a new series of hydrophilic polyethylene glycol-functionalized room-temperature ionic liquids, offering interesting thermo- and electrochemical behavior as well as remarkable surface properties. A scalable and generally applicable synthetic procedure for the preparation of N,N’-bis(polyethylene glycol)imidazolium salts, generally abbreviated as [(mPEGn)2Im][A] (n = 2‒6, A = I‒, OMs‒, PF6‒, NTf2‒) was developed. These ionic liquids were studied concerning their thermo- and electrochemical properties, such as phase transition behavior, decomposition temperature, viscosity, and density, as well as electrical conductivity and electrochemical stability, using i.a. differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV). Additionally, the surface properties were investigated by angle-resolved X-ray photoelectron spectroscopy (ARXPS) and the pendant drop method. olecular dynamics simulations complement the studies and provide insight into the molecular structure of the ionic liquids and their specific orientation at the liquid-vacuum interface.<br

Bis(pyrazol-1-yl)acetic acid bearing ferrocenyl substituents - Tampier, Stefan; Bleifuß, Sascha; Abd-Elzaher, Mokhles M.; Sutter, Jörg; Heinemann, Frank Wilhelm; Burzlaff, Nicolai (Organometallics, 2013)
The new compound 4-ferrocenyl-3,5-dimethylpyrazole (4; fcdmpzH) has been synthesized from 4-iodo-3,5-dimethyl-1-tritylpyrazole (2) via a Negishi type cross-coupling reaction and subsequent deprotection of the intermediate 4-ferrocenyl-3,5-dimethyl-1-tritylpyrazole (3; fcdmpzTrt). Reaction of the pyrazole 4 with dichloromethane, base, and phase transfer catalyst results in the chelating N,N ligand bis(4-ferrocenyl-3,5-dimethylpyrazol-1-yl)methane (5; bfcdmpzm). Bis(4-ferrocenyl-3,5-dimethylpyrazol-1-yl)ketone (6; bfcdmpzk) is obtained by reacting 4 with NEt and triphosgene. The N,N,O heteroscorpionate ligand bis(4-ferrocenyl-3,5-dimethylpyrazol-1-yl)acetic acid (7; H[bfcdmpza]) can be accessed by reacting pyrazole 4 with dibromoacetic acid, KOtBu, and phase transfer catalyst and subsequent acidic workup. The heteroscorpionate ligand H[bfcdmpza] (7) is suitable to bind metal ions in a κ coordination mode, as could be proven by the formation of a the bis-ligand complex [Fe(bfcdmpza)] (8). The molecular structures of 3, 5, 6, and 8 have been obtained by single-crystal X-ray structure determination. The electrochemical properties of the four ferrocenyl-substituted compounds 3-6 have been studied by cyclic voltammetric measurements and discussed as well. © 2013 American Chemical Society.

Bis(triazinyl)pyridine complexes of Pt(II) and Pd(II): studies of the nucleophilic substitution reactions, DNA/HSA interactions, molecular docking and biological activity - Jovanovic-Stevic, Snezana; Radisavljevic, Snezana; Scheurer, Andreas; Cocic, Dusan; Smit, Biljana; Petkovic, Marijana; Zivanovic, Marko N.; Virijevic, Katarina; Petrovic, Biljana (Journal of Biological Inorganic Chemistry, 2021)
Four new complexes of Pt(II) and Pd(II), [Pd(L1)Cl]Cl 1, [Pd(L2)Cl]Cl 2, [Pt(L1)Cl]Cl 3 and [Pt(L2)Cl]Cl 4 (where L1 = 2,6-bis(5,6-diphenyl-1,2,4-triazin-3-yl)pyridine and L2 = 2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine), were synthesized. Characterization of the complexes was performed using elemental analysis, IR, 1H NMR spectroscopy and MALDI-TOF mass spectrometry. The substitution reactions of 1–4 complexes with l-methionine (l-met), l-cysteine (l-cys) and guanosine-5ʹ-monophosphate (5ʹ-GMP), were studied spectrophotometrically at physiological conditions. Complexes with ligand L1 (1 or 3) were more reactive than those with ligand L2 (2 or 4) by a factor ranging up to 1.57 and 3.71, respectively. The order of reactivity of the nucleophiles was: l-met > l-cys > 5ʹ-GMP. The interactions of complexes with calf thymus-DNA (CT-DNA) and human serum albumin (HSA) were studied by Uv–Vis absorption and fluorescence emission spectroscopy. Competitive binding studies with intercalative agent ethidium bromide (EB) and minor groove binder Hoechst 33258 were performed as well. All studied complexes can interact with DNA through the intercalation and minor groove binding, where the latter was preferred. The binding constants (103 and 104 M−1) for the interaction of complexes with HSA indicate the moderate binding affinity of complexes 1–4 to protein. The trends in the experimental results of binding studies between complexes 3 and 4 with DNA and HSA were compared to those obtained from the molecular docking study. Biological evaluation of cytotoxicity of 1 and 2 on HCT-116 and MDA-MB-231 cell lines showed significant cytotoxic and prooxidative character, while 2 also exerted extraordinary selectivity towards colon cancer in comparison to breast cancer cells. Graphic abstract: The nucleophilic substitution reactions, DNA/HSA interactions, molecular docking and biological activity of bis(triazinyl)pyridine complexes of Pt(II) and Pd(II) were studied. [Figure not available: see fulltext.]
CRIS-Team Scopus Importer:2021-07-30
Keywords: Bis(triazinyl)pyridine; Cytotoxicity; DNA/HSA interaction; Kinetics; Molecular docking; Pd(II)/Pt(II) complexes; Redox status

Black Magic in Gray Titania: Noble-Metal-Free Photocatalytic H2 Evolution from Hydrogenated Anatase - Liu, Ning; Zhou, Xuemei; Nguyen, Nhat Truong; Peters, Kristina; Zoller, Florian; Hwang, Imgon; Schneider, Christopher; Miehlich, Matthias; Freitag, Detlef; Meyer, Karsten; Fattakhova-Rohlfing, Dina; Schmuki, Patrik (Chemsuschem, 2017)
‘Black’ TiO2—in the widest sense, TiO2reduced by various treatments—has attracted tremendous scientific interest in recent years because of some outstanding properties; most remarkably in photocatalysis. While the material effects visible light absorption (the blacker, the better), black titania produced by high pressure hydrogenation was recently reported to show another highly interesting feature; noble-metal-free photocatalytic H2generation. In a systematic investigation of high-temperature hydrogen treatments of anatase nanoparticles, TEM, XRD, EPR, XPS, and photoelectrochemistry are used to characterize different degrees of surface hydrogenation, surface termination, electrical conductivity, and structural defects in the differently treated materials. The materials’ intrinsic activity for photocatalytic hydrogen evolution is coupled neither with their visible light absorption behavior nor the formation of amorphous material, but rather must be ascribed to optimized and specific defect formation (gray is better than black). This finding is further confirmed by using a mesoporous anatase matrix as a hydrogenation precursor, which, after conversion to the gray state, even further enhances the overall photocatalytic hydrogen evolution activity.
CRIS-Team Scopus Importer:2020-09-14
Keywords: absorption; hydrogen evolution; hydrogenation; photocatalysis; titania

Bond Activation in Iron(II) and Nickel(II) Complexes of Polypodal Phosphanes - Gentschow, Simon-Andreas; Kohl, Stephan W.; Bauer, Walter; Heinemann, Frank Wilhelm; Wiedemann, Dennis; Grohmann, Andreas (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2010)
A pyridine-derived tetraphosphane ligand (donor set: NP(4)) has been found to undergo remarkably specific C P bond cleavage reactions, thereby producing a ligand with an NP(3) donor set. The reaction may be reversed under suitable conditions, with regeneration of the original NP(4) ligand. In order to investigate the mechanism of this reaction, the NP(3) donor ligand C(5)H(3)N[CME(CH(2)PMe(2))(2)][CMe(2)(CH(2)PMe(2))] (11) was prepared, and its iron(II) complex 4 generated from Fe(BF(4))(2) center dot 6H(2)O, with methyl diethylphosphinite (7) as an additional monodentate ligand. Ligand 11 has, in addition to the NP(3) donor set, one methyl group in close contact with the iron center, reminiscent of an agostic M center dot center dot center dot H-C interaction. Depending on the stoichiometric amount of iron(II) salt, a side product 15 is formed, which has a diethylphosphane ligand instead of the phosphinite 7 coordinated to iron(II). While attempts to deprotonate the metal-coordinated methyl group in 4 were unsuccessful, the reaction was shown to occur in an alternative complex (18), which is similar to 4 but has a trimethylphosphane ligand instead of the phosphinite 7. The reaction of complex 15 with CO gave two different products, which were both characterized by single-crystal X-ray diffraction. One (19) is the dicarbonyl iron(II) complex of the triphosphane ligand 11, the other (3) is the carbonyl iron(II) complex of the tetraphosphane C(5)H(3)N[CMe(CH(2)PMe(2))(2)](2) (1). This suggests an intermolecular mechanism for the C-P bond formation in question.
Keywords: Bond Activation; N/P Ligands; Polypodal Ligands; Agostic Interaction; Iron; Nickel

Boronic acids as probes for investigation of allosteric modulation of the chemokine receptor CXCR3. - Bernat, Viachaslau; Admas, Tizita; Brox, Regine; Heinemann, Frank Wilhelm; Tschammer, Nuska (ACS Chemical Biology, 2014)
The chemokine receptor CXCR3 is a G protein-coupled receptor, which conveys extracellular signals into cells by changing its conformation upon agonist binding. To facilitate the mechanistic understanding of allosteric modulation of CXCR3, we combined computational modeling with the synthesis of novel chemical tools containing boronic acid moiety, site-directed mutagenesis, and detailed functional characterization. The design of boronic acid derivatives was based on the predictions from homology modeling and docking. The choice of the boronic acid moiety was dictated by its unique ability to interact with proteins in a reversible covalent way, thereby influencing conformational dynamics of target biomolecules. During the synthesis of the library we have developed a novel approach for the purification of drug-like boronic acids. To validate the predicted binding mode and to identify amino acid residues responsible for the transduction of signal through CXCR3, we conducted a site-directed mutagenesis study. With the use of allosteric radioligand RAMX3 we were able to establish the existence of a second allosteric binding pocket in CXCR3, which enables different binding modes of structurally closely related allosteric modulators of CXCR3. We have also identified residues Trp109(2.60) and Lys300(7.35) inside the transmembrane bundle of the receptor as crucial for the regulation of the G protein activation. Furthermore, we report the boronic acid 14 as the first biased negative allosteric modulator of the receptor. Overall, our data demonstrate that boronic acid derivatives represent an outstanding tool for determination of key receptor-ligand interactions and induction of ligand-biased signaling.

Bright luminescent lithium and magnesium carbene complexes - Pinter, Piermaria; Schüßlbauer, Christoph; Watt, Fabian A.; Dickmann, Nicole; Herbst-Irmer, Regine; Morgenstern, Bernd; Grünwald, Annette; Ullrich, Tobias; Zimmer, Michael; Hohloch, Stephan; Guldi, Dirk Michael; Munz, Dominik (Chemical Science, 2021)
We report on the convenient synthesis of a CNC pincer ligand composed of carbazole and two mesoionic carbenes, as well as the corresponding lithium- and magnesium complexes. Mono-deprotonation affords a rare "naked" amide anion. In contrast to the proligand and its mono-deprotonated form, tri-deprotonated s-block complexes show bright luminescence, and their photophysical properties were therefore investigated by absorption- and luminescence spectroscopy. They reveal a quantum yield of 16% in solution at ambient temperature. Detailed quantum-chemical calculations assist in rationalizing the emissive properties based on an Intra-Ligand-Charge-Transfer (ILCT) between the carbazolido- and mesoionic carbene ligands. (Earth-)alkali metals prevent the distortion of the ligand following excitation and, thus, by avoiding non-radiative deactivation support bright luminescence.
CRIS-Team WoS Importer:2021-05-07

Brightly Luminescent and Color-Tunable CsPbBr3 Nanocrystals with Enhanced Stability and Room Temperature Cubic Structure through Codoping with MnCl2 - Darwish, Elshaimaa; Elia, Jack; Fehn, Dominik; Köllner, David; Pourjafar, Amir; Christiansen, Silke; Meyer, Karsten; Webber, Kyle Grant; Brabec, Christoph; Batentschuk, Miroslaw; Osvet, Andres (Advanced Engineering Materials, 2024)
Lead halide perovskites have attracted much attention from the scientific community in recent years due to their attractive properties and their proven potential in many applications. Nevertheless, their stability and lead toxicity have remained a problem. Herein, the potential of manganese as a divalent dopant to offer better stability and replace a fraction of the toxic lead ions is investigated. Moreover, the reverse microemulsion method is used to obtain tunability in emission and bandgap by doping cesium lead bromide. Furthermore, cubic cesium lead bromide particles are managed to obtain at room temperature as a result of doping.
CRIS-Team Scopus Importer:2024-05-24
Keywords: light conversion; perovskite nanoparticle; semiconductor quantum dots

Broadband Setup for Magnetic-Field-Induced Domain Wall Motion in Cylindrical Nanowires - Wartelle, Alexis; Thirion, Christophe; Afid, Raja; Jamet, Segolene; Da Col, Sandrine; Cagnon, Laurent; Toussaint, Jean-Christophe; Bachmann, Julien; Bochmann, Sebastian; Locatelli, Andrea; Mentes, Tevfik Onur; Fruchart, Olivier (Institute of Electrical and Electronics Engineers (IEEE), 2015)
In order to improve the precision of domain wall (DW) dynamics measurements, we develop a coplanar waveguide-based setup, where the DW motion should be triggered by pulses of magnetic field. The latter are produced by the Oersted field of the waveguide as a current pulse travels toward its termination, where it is dissipated. Our objective is to eliminate a source of bias in DW speed estimation while optimizing the field amplitude. Here, we present the implementations of this concept for magnetic force microscopy and synchrotron-based investigation.
Keywords: Domain walls (DWs); high-frequency (HF) electronics; instrumentation; magnetization dynamics; micromagnetics

C2 and C1-Symmetric Camphopyrazole Dioxomolybdenum(VI) Complexes catalyze the Epoxidation of Cyclic Olefins - Aguilera, Tania; Pastrán, Jesús; Llovera, Ligia; Linden, Anthony; Herrera, Alberto Cesar; Venuti, Doménico; Agrifoglio, Giuseppe; Dorta, Romano (Zeitschrift für Anorganische und Allgemeine Chemie, 2023)
Dioxomolybdenum(VI) complexes (1-6) were prepared in good yields (≥79 %) using enantiopure C2 and C1-symmetric bidentate N,N-ligands (L1-L6) derived from (+)-camphor. The ligands and complexes were characterized by NMR spectroscopy, IR, and elemental analysis. Single crystal X-ray diffraction analyses of complexes 3, 4 and 6 confirmed the bidentate coordination modes of ligands L3, L4, and L6 and revealed distorted octahedral coordination geometries around the metal center. Complexes 3 and 6 form conformational isomers depending on the orientation of the substituents of the ligand aryl groups. Preliminary evaluation of the complexes as catalysts for the epoxidation of cyclohexene (81–93 % conversion) and cis-cyclooctene (66–94 % conversion) with cumyl hydroperoxide and 35 % w/w aqueous hydrogen peroxide (39–73 %) demonstrated their activity for oxygen atom transfer reactions, opening the way for asymmetric epoxidations.
CRIS-Team Scopus Importer:2023-09-15
Keywords: (+)-camphor; bis-pyrazole; dioxomolybdenum(VI); enantiopure chiral ligands; epoxidation

C-2-Symmetric (SO)N(SO) Suloxide Pincer Complexes of Mg and Pd: Helicity Switch by Ambidentate S/O-Coordination and Isolation of a Chiral Pd-Sulfenate - Seidel, Falk; Frieß, Sibylle; Heinemann, Frank Wilhelm; Chelouan, Ahmed; Scheurer, Andreas; Grasruck, Alexander; Herrera, Alberto Cesar; Dorta, Romano (Organometallics, 2018)
Quinine-based (R)-tert-butylsulfinate 3 reacts with tris-lithiated bis-arylamide 2 to afford gram-quantities of optically pure (S*O)N(S*O) sulfoxide pincer ligand (R,R)-4. Deprotonation of (R,R)-4 and p-Tol-substituted analogue (S,S)-5 with MgPh2 and BnK yields respective Mg and K amido-bis-sulfoxides 6–9. In Mg complexes 6 and 7, the sulfoxide functions are O-coordinated, thereby imparting a pronounced helicity to the ligand backbone. Transmetalation of 6 and 7 with [PdCl2(NCPh)2] affords the S,S-coordinated C2-symmetric and the O,S-coordinated C1-symmetric chlorido complexes 10 and 11, respectively, and reaction of potassium amides 8 and 9 with [PdCl(CH3)(COD)] leads to methyl-palladium pincer complexes 12 and 13, respectively. The crystal structures of 6, 7, 12, and 13 reveal a chameleonic ligand system with predictable behavior: (R)-configured 4 induces pronounced λ backbone helicity in the O-coordinated Mg-complex and weaker δ helicity in S-coordinated Pd-complexes, while (S)-configured ligand 5 mirrors this stereochemistry. S-Coordination induces stronger, C2-symmetric, steric crowding in the head-on quadrants compared to O-coordination. When (R,R)-4 is reacted with 2 equiv of [Pd(CH3)2(tmeda)], crystalline chiral Pd-sulfenate complex 16 forms by elimination of iso-butene and methane with inversion of configuration at the sulfenate S ato

[(C_6_H_4_S_2_)Ni(my-'S_3_')Fe(CO)(PMe_3_)_2_]: A Dinuclear [NiFe] Complex Modeling the [(RS)_2_Ni(my-SR)_2_Fe(CO)(L)_2_] Core of [NiFe] Hydrogenase Centers - Sellmann, Dieter; Geipel, Franz; Lauderbach, Frank; Heinemann, Frank Wilhelm (Angewandte Chemie International Edition, 2002)
UnivIS-Import:2017-03-24:Pub.2002.forsch.sonder.sfb583.c_6_h_

Cage chirality of P-C cage compounds: highly diastereoselective formation of diastereomeric P5-deltacyclenes, separation of diastereomers, and removal of the chiral auxiliary. - Hofmann, Martin; Höhn, Christine; Heinemann, Frank Wilhelm; Zenneck, Ulrich (Chemistry - A European Journal, 2009)
An effective cyclic addition reaction of diastereomeric (R*)diphenyltin-3,5-di(tert-butyl)-1,2,4-triphosphole derivatives 6 a-c (R* = (-)-cis-myrtanyl (a), (-)-trans-myrtanyl (b), m-(2-bornyl-2-ene)phenyl (c) with two equivalents of tert-butylphosphaalkyne 1 leads to 1:1 mixtures of diastereomeric stannylated pentaphosphadeltacyclene derivatives 7 a-c with seven stereogenic centers in the cage unit. The (-)-cis-myrtanyl derivative 7 a could be separated into its diastereomers; destannylation of diastereomer 7 a(RR) led to the P-H cage 8 as a pure enantiomer. Circular dichroism (CD) spectroscopy of the pure diastereomer 7 a(RR) and the enantiomer 8 give evidence for identical stereoisomers of the P(5)-deltacyclene cage units and prove a strong dominance of the chiral cages over the chiral auxiliary groups with respect to their chiroptical properties. Absolute X-ray structure investigations of the majority of the compounds presented in the paper reveal the details of the stereochemistry of the asymmetric P-C cage units. In this paper we demonstrated for the first time a general preparative route to stereochemically fully defined asymmetric P-C cage compounds by separation of diastereomers and replacement of the chiral auxiliary group.

Camphopyrazole-based N,N- and N,P-ligands and chiral complexes of Ni, Pd, and Rh: P-N bond activation upon Rh(I) complexation - Herrera, Alberto Cesar; Briceno, Alexander; Gonzalez, Teresa; Linden, Anthony; Heinemann, Frank Wilhelm; Agrifoglio, Giuseppe; Pastran, Jesus; Dorta, Romano (Tetrahedron-Asymmetry, 2016)
Enantiomerically pure C-1 and C-2-symmetric bidentate N,N- and N,P-ligands are accessible from (+)-camphor in good yields (60-90%). Modified syntheses of precursors 1 and 2 are disclosed as well as the crystal structures of three hydroxy-pyrazoline intermediates. Ligands 3, 4, 6, and 11 were fully characterized including an X-ray crystal structure of C-2-symmetric 6, which showed an E-configuration in the solid state. These ligands form complexes with Ni(II), Pd(II), and Rh(I) in good yields (84-96%); the X-ray crystal structures of complexes 12, 14, and 16 confirmed the bidentate coordination modes of ligands 4, 6, and 11 and distorted tetrahedral [for NON and square planar [for Rh(I)] coordination geometries. Furthermore, the structure of the Rh(I) complex 16 revealed the presence of a Ph2PCl ligand, which, along with spectroscopic data, is proof of an almost quantitative P-N bond cleavage upon coordination of ligand 11 to [RhCl(COD)](2). (C) 2016 Elsevier Ltd. All rights reserved.

Camphorpyrazolium-based chiral functional ionic liquids - Pastran, Jesus; Agrifoglio, Giuseppe; Gonzalez, Teresa; Briceno, Alexander; Dorta, Romano (Tetrahedron-Asymmetry, 2014)
The solvent-less quaternization of N-phenyl-camphorpyrazole 4 with BrC4H9,IC2H4OCH3, and IC2H4OC2-H4OC4H9 afforded the corresponding chiral pyrazolium halides 5a, 6a, and 7a in excellent yields. The anions were modified either by trihalide formation with Br-2 and 12, or by salt metathesis with LiNTf2 and NaCo(CO)(4). All pyrazolium salts bearing the di-ether side chain 7a-d were liquids at room temperature, while the X-ray crystal structure of the bis(trifluoromethylsulfonyl)amide salt of the corresponding mono-ether analogue 6c (mp 97 degrees C) revealed intermolecular H-bonding interactions. Furthermore, an improved protocol for the well-known but notoriously low-yielding synthesis of (+)-hydroxymethylene-camphor 3 is disclosed. (C) 2014 Elsevier Ltd. All rights reserved.

Can Metallocryptands act as Proton Cages? - DFT Study of Proton Afnity in [2.2.2]-analogous Metallocryptands Sind Metalloprotonencryptanden möglich? - DFT-Studie zur Protonenaffinität von [2.2.2]-analogen Metallocryptanden - Scheurer, Andreas; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2010)
Keywords: DFT calculations; Cryptand; Proton affinity; Metallocryptand; Proton sponge

Capped-tetrahedrally coordinated Fe(II) and Co(II) complexes using a "click"-derived tripodal ligand: Geometric and electronic structures - Schweinfurth, David; Demeshko, Serhiy; Khusniyarov, Marat; Dechert, Sebastian; Gurram, Venkatanarayana; Buchmeiser, Michael R.; Meyer, Franc; Sarkar, Biprajit (Inorganic Chemistry, 2012)

Carbamoyl derivatives of a pyridine-based tetraamine - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2007)
The reaction of four equivalents of phenyl or tert-butyl isocyanate with the pyridine-derived tetraamine 2,6-C5H3N[CMe(CH2NH2)(2)](2) in toluene gives high yields of the quadruply ureido substituted products 2,6-C5H3N[CMe(CH2R)(2)](2) [R = -NH(CO)NHPh and -NH(CO)(NHBu)-Bu-t]. Full spectroscopic data for both compounds are given. A single crystal X-ray structure determination of the phenyl derivative reveals an intricate network of both intra- and intermolecular hydrogen bonds involving the C=O and both NH functionalities in all ureido groups.
Keywords: tetrapodal pentadentate ligand; urea; chelates; hydrogen bonding

Carbene based photochemical molecular assemblies for solar driven hydrogen generation. - Peuntinger, Katrin; Pilz, T. David; Staehle, Robert; Schaub, Markus; Kaufhold, Simon; Petermann, Lydia; Wunderlin, Markus; Goerls, Helmar; Heinemann, Frank Wilhelm; Li, Jing; Drewello, Thomas; Vos, Johannes G.; et al. (Dalton Transactions, 2014)
Novel photocatalysts based on ruthenium complexes with NHC (N-heterocyclic carbene)-type bridging ligands have been prepared and structurally and photophysically characterised. The identity of the NHC-unit of the bridging ligand was established unambiguously by means of X-ray structural analysis of a heterodinuclear ruthenium-silver complex. The photophysical data indicate ultrafast intersystem crossing into an emissive and a non-emissive triplet excited state after excitation of the ruthenium centre. Exceptionally high luminescence quantum yields of up to 39% and long lifetimes of up to 2 μs are some of the triplet excited state characteristics. Preliminary studies into the visible light driven photocatalytic hydrogen formation show no induction phase and constant turnover frequencies that are independent on the concentration of the photocatalyst. In conclusion this supports the notion of a stable assembly under photocatalytic conditions.

Carbene derived diradicaloids-building blocks for singlet fission? - Munz, Dominik; Messelberger, Julian; Grünwald, Annette; Pinter, P.; Hansmann, Martin Leo (Chemical Science, 2018)

Carbonate formation from CO2 via oxo versus oxalate pathway: Theoretical investigations into the mechanism of uranium-mediated carbonate formation - Castro, Ludovic; Lam, Oanh P.; Bart, Suzanne C.; Meyer, Karsten; Maron, Laurent (Organometallics, 2010)
We report theoretical investigations of the reaction of [(( ArO)mes)U] with CO in order to support previously reported experimental data. Experimentally, the reaction in toluene leads to the immediate formation of the bridging carbonate complex [(( ArO)mes)U(μ- η:η-CO)] at room temperature. DFT calculations show that the preferred reaction pathway is a three-step mechanism: first, the formation of a dinuclear CO complex, followed by concomitant release of CO, forming the corresponding bridging μ-oxo species. The final step involves insertion of a CO molecule into a U-O bond, forming the carbonate product. Calculations reveal this three-step process to be thermodynamically favorable and kinetically accessible. An alternate pathway that proceeds through an oxalate dinuclear complex is also explored. Although the oxalate complex is calculated to be the thermodynamic product of the reaction, a high activation barrier prevents its formation. © 2010 American Chemical Society.

Carbon Dioxide Activation by a Palladium Terminal Imido Complex - Goodner, Stephen J.; Grünwald, Annette; Heinemann, Frank Wilhelm; Munz, Dominik (Australian Journal of Chemistry, 2019)
We recently reported the first example of a palladium(ii) terminal imido complex. We proposed that this complex features exceptional high nucleophilicity at the nitrogen atom and a peculiar zwitterionic electronic structure with an anti-bonding highest-occupied molecular orbital (HOMO). This complex swiftly activated moderately acidic CH, OH, and NH bonds and also reacted with dihydrogen. However, unambiguous nucleophilic reactivity with substrates not featuring a hydrogen atom could not be observed. Herein, we now show that this nucleophilic complex also reacts with CO2 to give a ring-strained four-membered palladium(ii) carbamate complex. Remarkably, the same product is obtained in the reaction of the related bisamido complex, albeit at a slower reaction rate. Density functional theory calculations indicate that the addition of CO2 does not proceed via initial 1,2-addition across the Pd-N bond, but instead through nucleophilic attack by the imido (amido respectively) nitrogen atom.
CRIS-Team Scopus Importer:2019-09-24

Carbon dioxide activation with sterically pressured mid- and high-valent uranium complexes - Bart, Suzanne C.; Anthon, Christian; Heinemann, Frank Wilhelm; Bill, Eckhard; Edelstein, N. M.; Meyer, Karsten (Journal of the American Chemical Society, 2008)
Sterically pressured mid- to high-valent uranium complexes with an aryloxide substituted triazacyclononane ligand scaffold, [((ArO) tacn)], were studied for carbon dioxide activation and transformation chemistry. The high valent uranium(V) imido species [(( ArO)tacn)U(NR)] (R = Bu, R′ = 2,4,6-trimethylphenyl (2-Bu); R = Ad, R′ = 2,4,6-trimethylphenyl (2-Ad); R = Bu, R′ = phenyl (3- Bu)) were synthesized and spectroscopically characterized. X-ray crystallography of the tert-butyl mesityl imido derivative, 2-Bu, reveals coordination of a bent imido fragment with a relatively long U-N bond distance of 2.05 Å. The mesityl imido complexes reacted with carbon dioxide, readily extruding free isocyanate to produce uranium(V) terminal oxo species, [((ArO)tacn)U(O)] (R = Bu (4- Bu), Ad (4-Ad)), presumably through multiple bond metathesis via a uranium(V) carbimate intermediate. Using the smaller phenyl imido fragment in 3-Bu slowed isocyanate loss, allowing the uranium(V) carbimate intermediate to undergo a second metathesis reaction, ultimately producing the diphenyl ureate derivative, [((ArO)tacn)U(NPh )CO] (5-Bu). Single crystal X-ray diffraction studies were carried out on both uranium(V) terminal oxo complexes and revealed short U-O bonds (1.85 Å) indicative of a formal U≡O triple bond. The electronic structure of the oxo U(V) complexes was investigated by electronic absorption and EPR spectroscopies as well as SQUID magnetization and DFT studies, which indicated that their electronic properties are highly unusual. To obtain insight into the reactivity of CO with U-N bonds, the reaction of the uranium(IV) amide species, [((ArO) tacn)U(NHMes)] (R = Bu (6-Bu), Ad (6-Ad) with carbon dioxide was investigated. These reactions produced the uranium(IV) carbamate complexes, [((ArO)tacn)U(CONHMes)] (R = Bu (7-Bu), Ad (7-Ad)), resulting from insertion of carbon dioxide into U-N(amide) bonds. The molecular structures of the synthesized uranium carbamate complexes highlight the different reactivities due to the steric pressure introduced by the alkyl derivatized tris(aryloxide) triazacyclononane ligand. The sterically open tert-butyl derivative creates a monodentate η-O bound carbamate species, while the sterically more bulky adamantyl-substituted compound forces a bidentate κ-O,O coordination mode of the carbamate ligand. © 2008 American Chemical Society.

Carbon dioxide insertion into uranium-activated dicarbonyl complexes - Zuend, Stephan Johann; Lam, Oanh P.; Heinemann, Frank Wilhelm; Meyer, Karsten (Angewandte Chemie International Edition, 2011)
Quick on the uptake: Uranium(III) complexes bearing hexadentate triazacyclononane macrocyclic ligands L engage di-and triketones in both one-and two-electron reduction pathways. The dinuclear enolate generated through one of these pathways reacts with carbon dioxide to generate a new C-C bond (see scheme). Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon xerogel based electric double layer capacitors with polymer gel electrolytes - Improving the performance by adjusting the type of electrolyte and its processing - Reichstein, Jakob; Reichenauer, Gudrun; Anneser, Katrin; Braxmeier, Stephan (Electrochimica Acta, 2018)
Polymer gel electrolytes for electric double layer capacitors (EDLC), also known as supercapacitors, represent a safe and low-cost alternative to liquid electrolytes. This study shows that EDLCs with polymer gel electrolytes may accomplish gravimetric capacitances comparable to or even higher than those of EDLCs with the same carbon electrodes and the respective ions in aqueous electrolyte. One of the most important parameters in this context is the effective electrode/electrolyte interface. This can be improved by using a suitable electrode and assembling method for the polymer electrolyte component. As polymer gel electrolytes we investigated polyvinyl alcohol (PVA) with either phosphoric or sulfuric acid as well as PVA and sulfuric acid with hydroxyethyl-cellulose as an additive in combination with porous carbon (xerogel) electrodes with different meso/macrostructures. The gravimetric capacitances determined for EDLCs with the sulfuric PVA electrolyte were considerable higher than those of EDLCs using phosphoric acid. Furthermore, the results of our study indicate a clear influence of the electrodes pore structure and the applied assembling method on the specific capacitance. The processing method providing the best contact between polymer electrolyte and electrode yields EDLCs with a gravimetric capacitance comparable to or even higher than that of EDLCs with liquid H2SO4. The experimental findings strongly suggest that micropores in the interconnected carbon backbone of the electrode including such in regions that are not in direct contact with the polymer gel phase - are saturated with electrolyte and contribute to the capacitance. (C) 2018 Elsevier Ltd. All rights reserved.
Keywords: Electric double layer capacitor; Polymer gel electrolyte; All-solid-state; Micropores; Carbon xerogel

Catalyst Supraparticles: Tuning the Structure of Spray-Dried Pt/SiO2 Supraparticles via Salt-Based Colloidal Manipulation to Control their Catalytic Performance - Groppe, Philipp; Reichstein, Jakob; Carl, Simon; Cuadrado Collados, Carlos; Niebuur, Bart Jan; Zhang, Kailun; Apeleo Zubiri, Benjamin; Libuda, Jörg; Kraus, Tobias; Retzer, Tanja; Thommes, Matthias; Spiecker, Erdmann; et al. (Small, 2024)
The structure of supraparticles (SPs) is a key parameter for achieving advanced functionalities arising from the combination of different nanoparticle (NP) types in one hierarchical entity. However, whenever a droplet-assisted forced assembly approach is used, e.g., spray-drying, the achievable structure is limited by the inherent drying phenomena of the method. In particular, mixed NP dispersions of differently sized colloids are heavily affected by segregation during the assembly. Herein, the influence of the colloidal arrangement of Pt and SiO2 NPs within a single supraparticulate entity is investigated. A salt-based electrostatic manipulation approach of the utilized NPs is proposed to customize the structure of spray-dried Pt/SiO2 SPs. By this, size-dependent separation phenomena of NPs during solvent evaporation, that limit the catalytic performance in the reduction of 4-nitrophenol, are overcome by achieving even Pt NP distribution. Additionally, the textural properties (pore size and distribution) of the SiO2 pore framework are altered to improve the mass transfer within the material leading to increased catalytic activity. The suggested strategy demonstrates a powerful, material-independent, and universally applicable approach to deliberately customize the structure and functionality of multi-component SP systems. This opens up new ways of colloidal material combinations and structural designs in droplet-assisted forced assembly approaches like spray-drying.
CRIS-Team Scopus Importer:2024-05-10
Keywords: catalysis; porosity; spray-drying; structure control; supraparticles

Catalytic C - H amination with unactivated amines through copper(II) amides - Wiese, Stefan; Badiei, Yosra M.; Gephart, Raymond T.; Mossin, Susanne; Varonka, Matthew S.; Melzer, Marie M.; Meyer, Karsten; Cundari, Thomas R.; Warren, Timothy H. (Angewandte Chemie International Edition, 2010)
En route to catalysis: Two equivalents of the three-coordinate copper(II) amide [(Cl NN)Cu]-NHAd participate in stoichiometric C - H amination by a H-atom abstraction/radical capture sequence. This active species may be generated through a copper(II) tert-butoxide intermediate to allow for the unprecedented catalytic amination of sp -C - H bonds with unactivated alkylamines. This method greatly expands the range of amines for catalytic C - H amination since most protocols require N-based electron-withdrawing groups. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytic Oxygenation of Hydrocarbons by Mono-mu-oxo Dicopper(II) Species Resulting from O-O Cleavage of Tetranuclear Cu-I/Cu-II Peroxo Complexes - Jurgeleit, Ramona; Grimm-Lebsanft, Benjamin; Floeser, Benedikt Maria; Teubner, Melissa; Buchenau, Soren; Senft, Laura; Hoffmann, Jonas; Naumova, Maria; Naether, Christian; Ivanovic-Burmazovic, Ivana; Ruebhausen, Michael; Tuczek, Felix (Angewandte Chemie International Edition, 2021)
One of the challenges of catalysis is the transformation of inert C-H bonds to useful products. Copper-containing monooxygenases play an important role in this regard. Here we show that low-temperature oxygenation of dinuclear copper(I) complexes leads to unusual tetranuclear, mixed-valent mu(4)-peroxo [Cu-I/Cu-II](2) complexes. These Cu4O2 intermediates promote irreversible and thermally activated O-O bond homolysis, generating Cu2O complexes that catalyze strongly exergonic H-atom abstraction from hydrocarbons, coupled to O-transfer. The Cu2O species can also be produced with N2O, demonstrating their capability for small-molecule activation. The binding and cleavage of O-2 leading to the primary Cu4O2 intermediate and the Cu2O complexes, respectively, is elucidated with a range of solution spectroscopic methods and mass spectrometry. The unique reactivities of these species establish an unprecedented, 100 % atom-economic scenario for the catalytic, copper-mediated monooxygenation of organic substrates, employing both O-atoms of O-2.
CRIS-Team WoS Importer:2021-05-14

Catching gaseous SO 2 in cone-type lanthanide complexes: An unexpected coordination mode for SO 2 in f-element chemistry - Benndorf, Paul; Schmitt, Sophia; Koeppe, Ralf; Ona-Burgos, Pascual; Scheurer, Andreas; Meyer, Karsten; Roesky, Peter W. (Angewandte Chemie International Edition, 2012)
Easy come, easy go: The first molecular SO complexes of the lanthanides (Ln=Sm, Eu) have been prepared. The compounds can reversibly coordinate gaseous SO . Concomitant with the addition and removal of SO , the color of the complexes changes reversibly (see scheme). The structures of the SO compounds could be confirmed in solution and in the solid state. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catching gaseous SO 2 in cone-type lanthanide complexes: An unexpected coordination mode for SO 2 in f-element chemistry - Scheurer, Andreas; et al. (Angewandte Chemie International Edition, 2012)
Keywords: rare-earth elements; SO 2 complexes; coordination compounds; lanthanides; cage compounds

Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts - Macinnis, Morgan C.; Demott, Jessica C.; Zolnhofer, Eva; Zhou, Jia; Meyer, Karsten; Hughes, Russell P.; Ozerov, Oleg V. (Chem, 2016)
One-electron oxidation of known (tBu3P)2M (1, M = Pd; 2, M = Pt) with [Ph3C][HCB11Cl11] leads to two-coordinate, monovalent cations of the formula [(tBu3P)2M][HCB11Cl11] (3, M = Pd; 4, M = Pt), which also possess linear geometry but with elongated M–P bonds. Spectroscopic and computational studies consistently show that the unpaired electron of the d9 configuration of 3 and 4 belongs to largely non-bonding orbitals: the s/dz2 hybrid for Pd and the degenerate dx2-y2/dxy pair for Pt. We show that molecular-orbital-based arguments alone are incapable of predicting or rationalizing the observed M–P bond lengthening on oxidation; correct prediction and rationalization are achieved only by inclusion of electrostatic and Pauli effects. This emphasizes the dangers of interpreting any perturbative changes in bond metrics solely on the basis of energies and occupancies of molecular orbitals; the inclusion of electrostatic and Pauli components is essential to providing a more complete picture.
EAM Import::2019-03-13