Syntheses and characterization of two dioxygen-reactive dinuclear macrocyclic schiff-base copper(I) complexes. - Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry, 2003)
The dinuclear copper(I) complex [Cu(2)L(1)(CH(3)CN)(2)](ClO(4))(2) (1, L(1) = 3,6,9,17,20,23-hexaazatricyclo[23.3.1.1]triaconta-1(29),2,9,11(30),12(13),14,16,23,25,27-decaene) has been structurally characterized. As previously described, intramolecular ligand hydroxylation (at the aromatic ring) was observed when 1 was reacted with dioxygen. A stopped-flow analysis of the reaction of 1 with dioxygen under different conditions did not allow a "dioxygen intermediate" to be spectroscopically detected. Detailed NMR and electrochemical data on 1 are also presented and evaluated for the first time. No copper(II) complexes of L(1) could be characterized due to hydrolysis of the compounds. In contrast, complex 2-differing from 1 only in an increase in the size of the chelate rings-did not undergo intramolecular hydroxylation when it was oxidized. The crystal structure of 2 is also described.

Syntheses and properties of metal-centered mixed-valent [NEt 4]MnII⊂[MnII 3Mn III 3Cl6(L)6] - Scheurer, Andreas; et al. (European Journal of Inorganic Chemistry)
Keywords: Cyclic voltammetry; Mixed valency; Manganese clusters; X-ray diffraction; Self-assembly

Syntheses, Characterization, and Magnetic Studies of Copper(II) Complexes with the Ligand N,N,N ',N '-Tetrakis(2-pyridylmethyl)-1,3-benzenediamine (1,3-tpbd) and its Phenol Derivative 2,6-Bis[bis(2-pyridylmethyl)amino]-p-cresol] (2,6-Htpcd) - Turba, Sabrina; Foxon, Simon P.; Beitat, Alexander; Heinemann, Frank Wilhelm; Petukhov, Konstantin; Müller, Paul; Walter, Olaf; Lloret, Francesc; Julve, Miguel; Schindler, Siegfried (Inorganic Chemistry, 2012)
The copper(II) complexes [Cu-4(1,3-tpbd)(2)(H2O)(4)(NO3)(4)](n)(NO3)(4n)center dot 13nH(2)O (1), [Cu-4(1,3-tpbd)(2)(AsO4)(ClO4)(3)(H2O)](ClO4)(2)center dot 2H(2)O center dot 0.5CH(3)OH (2), [Cu-4(1,3-tpbd)(2)(PO4)(ClO4)(3)(H2O)](ClO4)(2)center dot 2H(2)O.0.5CH(3)OH (3), [Cu-2(1,3-tpbd)-(PhO)(2)PO2(2)](2)(ClO4)(4) (4), and [Cu-2(1,3-tpbd)(PhO)PO3(2)(H2O)(0.69)-(CH3CN)(0.31)](2)(BPh4)(4)center dot Et2O center dot CH3CN (5) [1,3-tpbd=N,N,N',N'-tetrakis(2-pyridylmethyl)-1,3-benzenediarnine, BPh4- = tetraphenylborate] were prepared and structurally characterized. Analyses of the magnetic data of 2, 3, 4, and [Cu-2(2,6-tpcd)(H2O)Cl](ClO4)(2) (6) [2,6-tpcd = 2,6-bis[bis(2-pyridylmethyl)amino]-p-cresolate] show the occurrence of weak antiferromagnetic interactions between the copper(II) ions, the bis-terdentate 1,3-tpbd/2,6-tpcd, mu(4)-XO4 (X = As and P) mu(1,2)-OPO and mu-O-phenolate appearing as poor mediators of exchange interactions in this series of compounds. Simple orbital symmetry considerations based on the structural knowledge account for the small magnitude of the magnetic couplings found in these copper(II) compounds.

Syntheses, Characterization and Properties of Open-Chain Copper(I) Complexes - Utz, Diana; Kisslinger, Sandra; Heinemann, Frank Wilhelm; Hampel, Frank; Schindler, Siegfried (European Journal of Inorganic Chemistry, 2011)
The coordination chemistry of copper complexes with the ligand L(1) [L(1) = 7E-N(1)-benzylidene-N(2)-(E)-2-(benzyl-ideneamino)ethyl]ethane-1,2-diamine] has been investigated. For copper(I) complexes of L(1), the counterion determines the molecular structure in the solid state. The reaction of [Cu(CH(3)CN)(4)]PF(6) with L(1) yielded the mononuclear complex [Cu(CH(3)CN)]PF(6) (1), whereas dinuclear helical [Cu(2)(L(1))(2)](ClO(4))(2) (2) resulted from a similar reaction with [Cu(CH(3)CN)(4)]ClO(4). Both compounds have been structurally characterized, and their solution behaviour investigated. Structurally characterized [Cu(L(1))(PPh(3))]ClO(4) (3) has been synthesized by reacting 2 with PPh(3). Exposure of a solution of 1 towards dioxygen in CH(3)OH and CH(2)Cl(2) yielded the dinuclear complexes [Cu(2)(L(1))(2)(OCH(3))(2)](PF(6))(2) (4) and [Cu(2)(L(1))(2)(OH)(2)](PF(6))(2) (5), respectively. Both compounds have been fully characterized. During the oxidation reaction, no hydroxylation of L(1) occurred. The oxidation reaction of 1 has been studied by a chemical approach and by UV/Vis spectroscopy, indicating the formation of a peroxido-bridged species during the reaction. Furthermore, by reduction of the imine groups in L(1) the ligand L(2) [L(2) = N(1)-benzyl-N(2)-[2-(benzylamino)ethylethane-1,2-diamine] was obtained and the dinuclear copper(II) complex [Cu(2)(L(2))(2)Cl(3)]PF(6)center dot 2MeOH (6) has been structurally characterized.
Keywords: Copper; Macrocycles; Oxidation; Oxygen; Helical structures; Anion effect

Syntheses, characterization, and reactivity of copper complexes with tridentate N-donor ligands - Astner, Joerg; Weitzer, Markus; Foxon, Simon P.; Schindler, Siegfried; Heinemann, Frank Wilhelm; Mukherjee, Jhumpa; Gupta, Rajeev; Mahadevan, Viswanath; Mukherjee, Rabindranath (Inorganica Chimica Acta, 2008)
The reaction of dioxygen with the copper(I) complex of the tridentate ligand 1,1,4,7,7-pentamethyldiethylenetriamine (Me(5)dien) has been investigated using low-temperature stopped-flow techniques. The formation of a bis( mu-oxo)copper(III) complex as a reactive intermediate could be detected spectroscopically at low temperatures and a quantitative kinetic analysis was performed for this system. Crystal structures of the copper(II) complexes [(Me-bpa)Cu(Cl)(2)] (1), [(Me-bpa)Cu(Cl)(ClO(4))(2)] (2), [(MeL)Cu(Cl)(ClO(4))(2)] (3), and [(MeL)Cu(NCS)(2)] (4) (Me-bpa=N-methyl-[bis(2-pyridyl)methyl]amine; MeL=N-methyl-[(2-pyridyl)ethyl(2-pyridyl)methyl]amine) are reported. (c) 2007 Elsevier B.V. All rights reserved.
Keywords: reactivity with dioxygen; bis-oxo-dicopper(III) species; tridentate N-donor ligands; kinetics; copper complexes

Syntheses, characterization and reactivity of iron(II), nickel(II), copper(II) and zinc(II) complexes of the ligand N,N,N ',N '-tetrakis(2-pyridylmethyl)-benzene-1,3-diamine (1,3-tpbd) and its phenol derivative 2,6-bis[bis(2-pyridylmethyl)amino]-p-cresol (2,6-tpcd) - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2007)
N,N,N',N'-Tetrakis(2-pyridylmethyl)benzene-1,3-diamine (1,3-tpbd), a bis(tridentate) ligand, its protonated derivative, [1,3-tpbdH(2)](2+), and a series of new dinuclear complexes [Fe-2(1,3-tpbd)(CH3CN)(6)](ClO4)(4)center dot(CH3CN)(2)center dot(H2O)(0.5) (1), [Fe-2(1,3-tpbd)(DMF)(6)](ClO4)(4) (2), [Ni-2(1,3-tpbd)(DMF)(6)](ClO4)(4) (3), [Zn-2(1,3-tpbd)(CH3CN)(2)(SO3CF3)(2)(H2O)](SO3CF3)(2) (4), [Zn-2(1,3-tpbd)Cl-4]center dot H2O (5), [CuZn(1,3-tpbd)Cl-4] (7) and the tetranuclear copper(II) complex [Cu-2(1,3-tpbd)(2)(H2O)(2)](ClO4)(4)center dot 2H(2)O (8) have been prepared and structurally characterized. Complex 8, a so called "dimetallocyclophane", interestingly only formed in the presence of zinc ions and not when copper(II) ions were mixed stoichiometrically (1:1 mixtures) under aerobic conditions. Theoretical calculations provide evidence for the formation of a side-on dinuclear peroxido copper complex during the oxidation of the (1, 3-tpbd) copper (1) complex. A possible reaction product, the dinuclear copper complex [Cu-2(2,6-tpcd)(H2O)(Cl)](ClO4)(2)center dot 2H(2)O (9) of a phenolate derivative of 1,3-tpbd was synthesized and structurally characterized independently from oxidation reactions from copper(II) perchlorate and the ligand 2,6-bis[bis(2-pyridylmethyl)amino]-p-cresol. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Keywords: iron; copper; zinc; ligand effects

Syntheses, emission properties and intramolecular ligand exchange of zinc complexes with ligands belonging to the tmpa family - Beitat, Alexander; Foxon, Simon P.; Brombach, Christoph-Cornelius; Hausmann, Heike; Heinemann, Frank Wilhelm; Hampel, Frank; Monkowius, Uwe; Hirtenlehner, Christa; Knoer, Guenther; Schindler, Siegfried (Dalton Transactions, 2011)
The zinc complexes [(L1)(2)Zn(MeOH)(2)](OTf)(2), [(L1)ZnCl2], [(L-2)ZnCl2], [(L2)Zn(OTf)(H2O)]OTf and [(Me-bispic)ZnCl2] of the ligands N-[(2-pyridyl)methyl]-2,2'-dipyridylamine (L1), N-[bis(2-pyridyl)methyl]-2-pyridylamine (L2) and N-methyl-[bis(2-pyridyl) methyl]amine (Me-bispic) were synthesised and characterised. The first copper(I) complexes of the ligands L1 and L2 were also synthesised and structurally characterised. [(L1)ZnCl2] showed unexpected fluxional behaviour in solution and revealed an interesting intramolecular ligand exchange mechanism in the coordination sphere of the zinc ion. Furthermore, strong blue emission was observed under UV-light excitation.

Syntheses of C2-symmetric vicinal diamines derived from tartaric acid - Scheurer, Andreas; et al. (Tetrahedron-Asymmetry, 1999)

Syntheses, structures and properties of copper(I) and copper(II) complexes of the ligand N,N'-bis[2'-(dimethylamino)ethyl]-N,N'- dimethylethane-1,2-diamine (Me6trien) - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2000)
Keywords: Coordination chemistry; Bioinorganic chemistry; Oxidations; Copper; Oxygen

Syntheses, structures and reactivity of electron-rich Fe and Ru complexes with the new pentadentate ligand Et2NpyS4-H2 4-(diethylamino)-2,6-bis[(2-mercaptophenyl)thiomethyl]pyridine - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2004)
Keywords: Electron density; Nitrogenase; Iron; S ligand; Ruthenium

Synthese und Charakterisierung von kronenetherstabilisierten Platin(IV)-Komplexen mit Aminosäureliganden - Steinborn, Dirk; Gravenhorst, Olaf; Junicke, H.; Heinemann, Frank Wilhelm (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 1998)

Synthese und Kristallstruktur von 3,3-Bis(alkylthio)-2-(2-thioxo-benzo-2H-1,3-thiazol-3-yl)-acrylsäure-Derivaten - Dölling, W.; Herrmann, C.; Augustin, M.; Ahnert, R.; Heinemann, Frank Wilhelm (Monatshefte für Chemie, 1991)

Synthese und Struktur der Kronenetherkomplexe von Kaliumhexachlorodipalladat(II) und -diplatinat(II) - Gerisch, M.; Heinemann, Frank Wilhelm; Markgraf, U.; Steinborn, Dirk (Zeitschrift für Anorganische und Allgemeine Chemie, 1997)

Synthese von 5-Methylthio-2-thioxo-1,3-dithiol-4-carbonsäureamiden und -thiolestern, 3-Alkyl-5-bis(alkylthio)-methylen-2-thioxo-1,3-thiazol-4-(5H)-onen sowie Röntgenkristallstrukturanalyse des 5-Methylthio-2-thioxo-1,3-dithiol-4-carbonsäure-(N-methyl-anilids - Dölling, W.; Friedemann, K.; Heinemann, Frank Wilhelm; Hartung, H (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 1991)

Synthesis and catalytic applications of chiral hydridoiridium(III) complexes with diamine/bis(monophosphane) and diamine/diphosphane coordination - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2007)
The P-2/N-2-coordinated cis-dihydridoiridium(III) chelate complexes (OC-6-13)-[IrH2(H(2)NnNH(2))(PR3)(2)]BF4 [PR3 = PPh3, H(2)NnNH(2) = 1,2-(H2N)(2)C6H4 (1a); (lR,2R)-(H2N)(2)C6Ho J(R,R)-dach) (1b); (R)-2,2'-diamino-1,1'-binaphthyI I(R)dabinj (1c); PR3 = PiPr(3), H(2)NnNH(2) = (R,R)-dach (2a), (R)dabin (2b); PR3 = PC gamma 3, H2NnNH(2) = (R)-dabin (3)] were obtained by treating the respective diamine ligands with labile precursors such as [1rH(2)(OCMe2)(2)(PPh3)2]BF4, [(ill-1,5C8Hl2)lr(PPh3)2]BF4, or [IrH5(PR3)(2)]/HBF4 (R = iPr, Cy). While oxidative addition of HCl to f(Tl'-1,5-C8H12)lrj(S,S)bdpcp)]BF4 [(S,S)-bdpcp = (lS,2S)-(Ph2P)2C5H8] yields the usual mononuclear adduct [(q4_l,5-C8H12)Ir(H)(Cl)((S,S)bdpcp)]BF4 (4), similar treatment of [(fl4_ 1,5-C8H12)Irj(R)binap)]BF4 furnishes the triply chlorido-bridged diiridium complex [j(R)-binap)2lr2H2(V-Cl)3jBF4 (5). Opening of the pCl bridges of 5 by N,N nucleophiles was used to synthesise the three diamine/(R)-binap complexes [lr(H)(Cl)(H2NnNH2fflR)-binap)jBF4 IH,NnNH2 (lR,2R)H2NCH(Ph)CH(Ph)NH2 j(R,R)-dpen) (6a), (R,R)-dach (6b), and H2NCMe2CMe2NH2 Itmen) (6c). Whereas the dihydrides [IrH2YR,R)-dachj(PR3)2]BF4 and [lrH2YR)-dabinj(PR3)2]BF4 (R = iPr, Ph) are only poor (pre)catalysts for the enantioselective hydrogenation of acetophenone, complexes 6a-c catalyze the formation of 1-phenylethanol in good enantiomeric excess [ee a. = 82-84 % (S)] in the presence of base. The crystal structures of la, 4, and 5 have been determined.
Keywords: iridium; N ligands; P ligands; asymmetric catalysis

Synthesis and characterization of an Fe(I) cage complex with high stability towards strong H-acids - Voloshin, Yan Z.; Novikov, Valentin V.; Nelyubina, Yulia; Belov, Alexander S.; Roitershtein, Dmitrii M.; Savitsky, Anton; Mokhir, Andriy; Sutter, Jörg; Miehlich, Matthias; Meyer, Karsten (Chemical Communications, 2018)

Synthesis and Characterization of a Trisheteroleptic Ru-II-Based Molecular Switch - Monczak, Katharina; Peuntinger, Katrin; Sorsche, Dieter; Heinemann, Frank Wilhelm; Guldi, Dirk Michael; Rau, Sven (Chemistry - A European Journal, 2014)
The synthesis of a trisheteroleptic ruthenium complex [Ru(tb)(dppz)(tmbiH(2))][PF6](2) (tb = 4,4'-di-tert-butyl-2,2'-bipyridine, dppz = dipyrido[3,2-a:2',3'-c]phenazin, tmbiH(2) = 5,6,5',6'-tetramethyl-2,2'-bibenzimidazole) is described. In addition, the structural characterisation by means of 1D, 2D H-1 NMR spectroscopy, and mass spectrometry, along with determination of the solid-state structure of the important precursor Ru(tb)(dppz) Cl-2, supports the proposed octahedral coordination geometry. The capability of tmbiH(2) to form hydrogen bonds is corroborated by the solid-state structure. The photochemical characteristics of this complex can be described as a combination of the "light switch" effects, which are either attributed to the dppz or to the tmbiH(2) ligand. To illustrate the molecule's double switchable features, steady-state absorption and emission measurements were performed, which include the determination of the quantum yield and the pK(a) values of the acidic protons of the tmbiH(2) ligand. Notably, the emission lifetimes are sensitive to the solvents used. This phenomenon is due to a proton-coupled deactivation of the excited metal-to-ligand charge transfer (MLCT) state of the complex.
Keywords: bibenzimidazole; light switch effect; molecular switch; pH dependency; trisheteroleptic Ru-II complex

Synthesis and Characterization of a Uranium(II) Monoarene Complex Supported by delta Backbonding - la Pierre, Henry Storms; Scheurer, Andreas; Heinemann, Frank Wilhelm; Hieringer, Wolfgang; Meyer, Karsten (Angewandte Chemie International Edition, 2014)
The low-temperature (<−35 °C) reduction of the trivalent uranium monoarene complex [(Ad,MeArO)3mesU] (1), with potassium spheres in the presence of a slight excess of 2.2.2-cryptand, affords the quantitative conversion of 1 into the uranium(II) monoarene complex [K(2.2.2-crypt)][((Ad,MeArO)3mes)U] (1-K). The molecular and electronic structure of 1-K was established experimentally by single-crystal X-ray diffraction, variable-temperature 1H NMR and X-band EPR spectroscopy, solution-state and solid-state magnetism studies, and optical absorption spectroscopy. The electronic structure of the complex was further investigated by DFT calculations. The complete body of evidence confirms that 1-K is a uranium(II) monoarene complex with a 5f 4 electronic configuration supported by δ backbonding and that the nearly reversible, room-temperature reduction observed for 1 at −2.495 V vs. Fc/Fc+ is principally metal-centere
Keywords: arenes; electronic structure; magnetic properties; uranium; X-ray diffraction

Synthesis and characterization of a uranium(II) monoarene complex supported by δ backbonding. - la Pierre, Henry Storms; Scheurer, Andreas; Heinemann, Frank Wilhelm; Hieringer, Wolfgang; Meyer, Karsten (Angewandte Chemie-International Edition, 2014)
The low-temperature (<-35 °C) reduction of the trivalent uranium monoarene complex [((Ad,Me) ArO)3 mesU] (1), with potassium spheres in the presence of a slight excess of 2.2.2-cryptand, affords the quantitative conversion of 1 into the uranium(II) monoarene complex [K(2.2.2-crypt)][(((Ad,Me) ArO)3 mes)U] (1-K). The molecular and electronic structure of 1-K was established experimentally by single-crystal X-ray diffraction, variable-temperature (1) H NMR and X-band EPR spectroscopy, solution-state and solid-state magnetism studies, and optical absorption spectroscopy. The electronic structure of the complex was further investigated by DFT calculations. The complete body of evidence confirms that 1-K is a uranium(II) monoarene complex with a 5f (4) electronic configuration supported by δ backbonding and that the nearly reversible, room-temperature reduction observed for 1 at -2.495 V vs. Fc/Fc(+) is principally metal-centered.

Synthesis and characterization of cerium and yttrium alkoxide complexes supported by ferrocene-based chelating ligands - Broderick, Erin M.; Thuy-Boun, Peter S.; Guo, Neng; Vogel, Carola; Sutter, Jörg; Miller, Jeffrey T.; Meyer, Karsten; Diaconescu, Paula L. (Inorganic Chemistry, 2011)
Two series of Schiff base metal complexes were investigated, where each series was supported by an ancillary ligand incorporating a ferrocene backbone and different N=X functionalities. One ligand is based on an imine, while the other is based on an iminophosphorane group. Cerium(IV), cerium(III), and yttrium(III) alkoxide complexes supported by the two ligands were synthesized. All metal complexes were characterized by cyclic voltammetry. Additionally, NMR, Mössbauer, X-ray absorption near-edge structure (XANES), and absorption spectroscopies were used. The experimental data indicate that iron remains in the +2 oxidation state and that cerium(IV) does not engage in a redox behavior with the ancillary ligand. © 2011 American Chemical Society.

Synthesis and Characterization of cis- and trans-Tetrachlorobis(pyridine)- platinum(IV) - Junicke, H.; Schenzel, K.; Heinemann, Frank Wilhelm; Pelz, Kuno; Bögel, H.; Steinborn, Dirk; et al. (Zeitschrift für Anorganische und Allgemeine Chemie, 1997)

Synthesis and characterization of divalent manganese, iron, and cobalt complexes in tripodal phenolate/N-heterocyclic carbene ligand environments - Käß, Martina; Hohenberger, Johannes; Adelhardt, Mario; Zolnhofer, Eva; Mossin, Susanne; Heinemann, Frank Wilhelm; Sutter, Jörg; Meyer, Karsten (Inorganic Chemistry, 2014)
Two novel tripodal ligands, (BIMPN) and (MIMPN), combining two types of donor atoms, namely, NHC and phenolate donors, were synthesized to complete the series of N-anchored ligands, ranging from chelating species with tris(carbene) to tris(phenolate) chelating arms. The complete ligand series offers a convenient way of tuning the electronic and steric environment around the metal center, thus, allowing for control of the complex's reactivity. This series of divalent complexes of Mn, Fe, and Co was synthesized and characterized by H NMR, IR, and UV/vis spectroscopy as well as by single-crystal X-ray diffraction studies. Variable-temperature SQUID magnetization measurements in the range from 2 to 300 K confirmed high-spin ground states for all divalent complexes and revealed a trend of increasing zero-field splitting |D| from Mn(II), to Fe(II), to Co(II) complexes. Zero-field Fe Mössbauer spectroscopy of the Fe(II) complexes 3, 4, 8, and 11 shows isomer shifts δ that increase gradually as carbenes are substituted for phenolates in the series of ligands. From the single-crystal structure determinations of the complexes, the different steric demand of the ligands is evident. Particularly, the molecular structure of 1 - in which a pyridine molecule is situated next to the Mn-Cl bond - and those of azide complexes 2, 4, and 6 demonstrate the flexibility of these mixed-ligand derivatives, which, in contrast to the corresponding symmetrical TIMEN ligands, allow for side access of, e.g., organic substrates, to the reactive metal center. © 2013 American Chemical Society.

Synthesis and characterization of iron trisphenolate complexes with hydrogen-bonding cavities - Adelhardt, Mario; Chalkley, Matthew; Heinemann, Frank Wilhelm; Sutter, Jörg; Scheurer, Andreas; Meyer, Karsten (Inorganic Chemistry, 2014)
A new family of C-symmetric ligands, featuring phenolate donors and a secondary coordination sphere, have been synthesized. We report the synthesis and subsequent coordination chemistry of these new tripodal N-anchored tris(phenolate) chelates, [tris(5-tert-butyl-3-N-carboxamide-2-hydroxybenzyl) amines] (HSalAmi), to iron(II), iron(III), and zinc(II). These electron-rich complexes have intramolecular hydrogen bonds, and therefore the potential to stabilize biologically relevant substrates in small-molecule activation chemistry. © 2014 American Chemical Society.

Synthesis and characterization of metal-centered, six-membered, mixed-valent, heterometallic wheels of iron, manganese, and indium. - Heinemann, Frank Wilhelm; et al. (Chemistry - A European Journal, 2006)
Heptanuclear metal-centered, six-membered, mixed-valent, heterometallic wheels 1-3 of iron, manganese, and indium were prepared in a one-pot reaction from N-benzyldiethanolamine (H2L(1)), cesium carbonate, [PPh4]2[MnCl4], and FeCl3 or InCl3. All three complexes were characterized by the combination of elemental analysis, FAB mass spectroscopy, X-ray diffraction and cyclic voltammetry and in the case of 1 additionally by Mössbauer spectroscopy. In 1, four Mn(II) ions in the periphery are arranged in pairs alternating with one Fe(III) ion each, with an Fe(III) ion located in the center. In 2, three Mn(II) ions alternate with three In(III) ions, whereas in 3, four In(III) ions are arranged in pairs and alternate with one Mn(II) ion each. In 2 and 3 an Mn(II) ion is encapsulated in the center.

Synthesis and characterization of Platinum(II) complexes with terminal alkynes analogous to Zeise’s salt - structure of [K(18-crown-6)][PtCl3(PhCCD)]•CH2Cl2 - Gerisch, M.; Heinemann, Frank Wilhelm; Bögel, H.; Steinborn, Dirk (Journal of Organometallic Chemistry, 1997)

Synthesis and characterization of regioselective substituted tetrapyridophenazine ligands and their Ru(II) complexes - Karnahl, Michael; Tschierlei, Stefanie; Kuhnt, Christian; Dietzek, Benjamin; Schmitt, Michael; Popp, Jürgen; Schwalbe, Matthias; Krieck, Sven; Goerls, Helmar; Heinemann, Frank Wilhelm; Rau, Sven (Dalton Transactions, 2010)
A series of novel regioselective substituted tpphz ligands and two novel mononuclear ruthenium complexes of the type [(tbbpy)(2)Ru(tpphzRn)](PF(6))(2) (where tbbpy = 4,4'-di-tert.-butyl-2,2'-bipyridine, tpphz = tetrapyrido[3,2-a:2',3'-c:3 '',2 ''-h:2''',3'''-j]phenazine, with n = 2 and R represents the bromine substituents at different positions) have been synthesized. All compounds were completely characterized by NMR and MS spectroscopy, absorption and steady-state emission spectroscopy as well as emission lifetime and electrochemical measurements. Additionally the solid-state structures of the two isomers [(tbbpy)(2)Ru(Br(2)tpphz)](PF(6))(2) 6 and [(tbbpy)(2)Ru(tpphzBr(2))](PF(6))(2) 7 are presented and compared with the results of density-functional theory calculations (DFT). Furthermore calculated Raman spectra were obtained by means of DFT calculations and used to assign the vibrational modes of the measured off resonance Raman spectra. A clear influence caused by the electronic effects of the different type and position of the substituents of tpphz on the photophysical behavior was observed.

Synthesis and Characterization of (smif) 2M n (n = 0, M = V, Cr, Mn, Fe,Co, Ni, Ru; N = +1, M = Cr, Mn, Co, Rh, Ir; Smif =1,3-di-(2-pyridyl)-2-azaallyl) - Frazier, Brenda A.; Bartholomew, Erika R.; Wolczanski, Peter T.; Debeer, Serena; Santiago-Berrios, Mitk'El; Abruna, Hector D.; Lobkovsky, Emil B.; Bart, Suzanne C.; Mossin, Susanne; Meyer, Karsten; Cundari, Thomas R. (Inorganic Chemistry, 2011)
A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif) M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe ) (THF) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2- azapropene); ortho -methylated ( Mesmif) Fe (2-Fe) and ( Me2smif) Fe (3-Fe) were similarly prepared. Metatheses of MX variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl3(THF) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl (THF) in the presence of NaBPh gave [(smif) Ir]BPh (1+-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)2M]OTf (1+-M), and treatment of Rh (O CCF ) with 4 equiv Na(smif) and 2 AgOTf gave 1+-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (σ ≈ 10 000-60 000 M cm ), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy k-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr. © 2011 American Chemical Society.

Synthesis and Characterization of Stable Iron Pentacarbonyl Radical Cation Salts - Rall, Jan M.; Schorpp, Marcel; Keilwerth, Martin; Maylander, Maximilian; Friedmann, Christian; Daub, Michael; Richert, Sabine; Meyer, Karsten; Krossing, Ingo (Angewandte Chemie International Edition, 2022)
The open-shell iron pentacarbonyl cation [Fe(CO)(5)](.+) was isolated by deelectronation, i.e., the single-electron oxidation of the parent neutral Fe(CO)(5) using [phenazine(F)](.+) as the [Al(ORF)(4)](-) and [F-Al(ORF)(3)(2)](-) salt (R-F=C(CF3)(3); phenazine(F)=perfluoro-5,10-bis(perfluorophenyl)-5,10-dihydrophenazine). [Fe(CO)(5)](.+)[Al(ORF)(4)](-) was fully characterized (scXRD analysis, IR, NMR, EPR, Fe-57 spectroscopy, CV and SQUID magnetization study) and, apart from being a compound of fundamental interest, may serve as a precursor for low-valent iron coordination chemistry.
CRIS-Team WoS Importer:2022-06-24

Synthesis and Characterization of Substituted (Aminomethyl)lithium Compounds. The Structures of [Li(CH2NPh2)2(thf)3] and [Li4(CH2NC5H10)4(thf)2] - Becke, F; Heinemann, Frank Wilhelm; Rüffer, T.; Wiegeleben, P.; Boese, Roland; Bläser, Dieter; Steinborn, Dirk (Journal of Organometallic Chemistry, 1997)

Synthesis and Characterization of Substituted (Thiomethyl)lithium Compounds Structures of [Li(CH2SMe)(thf) - Becke, F.; Heinemann, Frank Wilhelm; Steinborn, Dirk (Organometallics)

Synthesis and characterization of uranium(IV) tetrachloro complexes in bis-pyrazolylpyridine ligand environments. - Korzekwa, Jana; Scheurer, Andreas; Heinemann, Frank Wilhelm; Meyer, Karsten (Dalton Transactions, 2017)
Starting from dimethyl 2,6-pyridinedicarboxylate (3), four pyridine-bridged bispyrazole ligands 1a-1d were generated in a two- or three-step synthesis sequence and further treated with UCl4 to yield the corresponding novel mononuclear uranium(iv) complexes [UIV(R'''2L)(Cl)4] (2a-2d). Compounds 2a-2d were characterized by a variety of spectroscopic and physical methods (e.g. UV/Vis, SQUID, CV, etc.), corroborating the +4 oxidation state in 2a-2d. Single-crystal X-ray structure analyses revealed that 2a·2THF crystallizes in the orthorhombic space group Pbca, 2b·0.8THF·0.2Et2O in the monoclinic Sohncke space group P21, 2c·0.25Et2O in the monoclinic one P21/c, and finally 2d·0.5THF in the orthorhombic Sohncke space group P21212. In the solid state, complexes 2a-2d possess a distorted pentagonal-bipyramidal coordination sphere at the UIV centers and an out-of-plane shift (doop) of up to 1.12 Å, which can be explained by an increased steric pressure on the metal ions at the binding sites of the chelating ligands 1c and 1d. Finally, by combination of different 1D and 2D NMR experiments, the 1H and 13C resonances can be unequivocally assigned in the corresponding paramagnetic NMR spectra of 2a-2d.

Synthesis and crystal structure of N,N,N′,N″,N″-pentamethyldiethyl-enetriamine co-coordinated potassium bis(diphenylphosphanyl)amide Synthese und kristallstruktur von N,N,N′,N″,N″-pentamethyl-diethylentriamin-cokoordiniertem kalium-bis(diphenylphosphanyl)amid - Heinemann, Frank Wilhelm; et al. (Chemische Berichte, 1997)

Synthesis and Electrochemical and Photophysical Characterization of New 4,4-Conjugated 2,2-Bipyridines that are End-Capped with Cyanoacrylic Acid/Ester Groups - Fingerhut, Anja; Wu, Yanlin; Kahnt, Axel; Bachmann, Julien; Tsogoeva, Svetlana (Chemistry-An Asian Journal, 2016)
Two new functionalized 4,4-disubstituted 2,2-bipyridines that were end-capped with cyanoacrylic acid or cyanoacrylic acid ester anchoring groups, which might allow their efficient functionalization on TiO2 or other metal-oxide semiconductor surfaces, have been synthesized and characterized by electrochemical, photophysical, and spectroscopic measurements. The electrochemical and photophysical properties of these 4,4-disubstituted 2,2-bipyridines with extended systems, in particular their LUMO energies, make them promising candidates to build up inorganic-organic hybrid photosensitizers for the sensitization of metal-oxide semiconductors (e.g., TiO2 nanoparticles and/or nanotubes).
Keywords: adsorption; bipyridines; conjugation; fluorescence; photosensitizers

Synthesis and Electronic Structure of Dissymmetrical, Naphthalene-Bridged Sandwich Complexes [Cp ' Fe(mu-C10H8)MCp*](x) (x=0,+1; M = Fe, Ru; Cp ' = eta(5)-C5H2-1,2,4-tBu(3); Cp* = eta(5)-C5Me5) - Malberg, Jennifer; Lupton, Elizabeth; Schnoeckelborg, Eva-Maria; De Bruin, Bas; Sutter, Jörg; Meyer, Karsten; Hartl, Frantisek; Wolf, Robert (Organometallics, 2013)
The dissymmetrical naphthalene-bridged complexes [Cp'Fe(mu-C10H8)FeCp*] (3; Cp* = eta(5)-C5Me5, Cp' = eta(5)-C5H2-1,2,4-tBu(3)) and [Cp'Fe(mu-C10H8)RuCp*] (4) were synthesized via a one-pot procedure from FeCl2(thf)(1.5), Cp'K, KC10H8, and [Cp*FeCl(tmeda)] (tmeda = N,N,N',N'-tetramethylethylenediamine) or [Cp*RuCl](4), respectively. The symmetrically substituted iron ruthenium complex [Cp*Fe(mu-C10H8)RuCp*] (5) bearing two Cp* ligands was prepared as a reference compound. Compounds 3-5 are diamagnetic and display similar molecular structures, where the metal atoms are coordinated to opposite sides of the bridging naphthalene molecule. Cyclic voltammetry and UV/vis spectroelectrochemistry studies revealed that neutral 3-5 can be oxidized to monocations 3(+)-5(+) and dications 3(2+)-5(2+). The chemical oxidation of 3 and 4 with [Cp2Fe]PF6 afforded the paramagnetic hexafluorophosphate salts [Cp'Fe(mu-C10H8)FeCp*]PF6 ([3]PF6) and [Cp'Fe(mu-C10H8)RuCp*]PF6 ([4]PF6), which were characterized by various spectroscopic techniques, including EPR and Fe-57 Mossbauer spectroscopy. The molecular structure of [4]PF6 was determined by X-ray crystallography. DFT calculations support the structural and spectroscopic data and determine the compositions of frontier molecular orbitals in the investigated complexes. The effects of substituting Cp* with Cp' and Fe with Ru on the electronic structures and the structural and spectroscopic properties are analyzed.

Synthesis and exploratory coordination chemistry of the new ditertiary carbinamine ligand 2,6-bis(alpha-aminoisopropyl)pyridine - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 2007)
The new pyridine-based N boolean AND N boolean AND N tridentate ligand 2,6-C5H3N(CMe2NH2)(2) (1) was synthesized by the treatment of 2,6-pyridinedicarbonitrile with an excess of the organocerium reagent in situ generated from CeCl3 and methyllithium in THF. The reaction of 1 with [RuCl2(PPh3)(3)] in THF at ambient conditions afforded (OC-6-23)-[RuCl2,6-C5H3N(CMeNH2)(2)(PPh3)(2)]Cl (2). The corresponding dimethyl sulfoxide complex [RuCl2,6-C5H3N(CMe2NH2)(2) S(O)Me-2(2)]Cl (3) was isolated as a mixture of the (OC-6-23) and (OC-632) stercoisonters 3a and 3b from the reaction between 1 and (OC-6-22)-[RuCl2 S(O)Me-2(3)(OSMe2)] in toluene at 80 degrees C. A prolonged interaction in toluene at reflux temperature gave isomerically pure 3a. The metal trichloride hydrates MCl3 - xH(2)O (M = Ru, Rh, Ir; x congruent to 2-4) produced mer-[RuCl32,6-C5H3N(CMe2NH2)(2)] (M = Ru: 4; Rh: 5; Ir: 6), when combined with I in refluxing ethanol. The crystal structures of the following compounds were determined: ligand 1 and complexes 2 5 as addition compounds 2 - CH2Cl2, 3a (.) C7H8, ;4 (.) EtOH and 5 (.) 2(1)/2DMF. (c) 2006 Elsevier B.V. All rights reserved.
Keywords: 2; 6-bis(alpha-aminoisopropyl)pyridine; ruthenium complexes; rhodium complexes; iridium complexes; X-ray structure analysis

Synthesis and first X-ray structure of a hexa-peri-hexabenzocoronene-fullerene-dyad: a model for an inter-carbon-allotrope hybrid. - Kratzer, Andreas; Englert, Jan; Lungerich, Dominik; Heinemann, Frank Wilhelm; Jux, Norbert; Hirsch, Andreas (Faraday Discussions, 2014)
The synthesis of a new hexa-peri-hexabenzocoronene (HBC)-fullerene dyad was accomplished involving a covalent linkage between both the planar and the spherical conjugated π-system of the two chromophores. We also present the first X-ray single crystal structure of a HBC-fullerene conjugate. A very short HBC-fullerene distance of 3.2 Å is observed. For the synthesis of this molecule, a new versatile applicable template, namely, a mono-functionalized hexa-peri-hexabenzocoronene was attached to a fullerene. Absorption and fluorescence spectroscopy, as well as quantum yield measurements of , indicated close electronic communication between the two subunits, which is promising for possible applications in molecular electronics.

Synthesis and photophysics of a novel photocatalyst for hydrogen production based on a tetrapyridoacridine bridging ligand - Karnahl, Michael; Kuhnt, Christian; Heinemann, Frank Wilhelm; Schmitt, Michael; Rau, Sven; Popp, Juergen; Dietzek, Benjamin (Chemical Physics, 2012)
Molecular photocatalysts allow for selectively tuning their function on a molecular level based on an in-depth understanding of their chemical and photophysical properties. This contribution reports the synthesis and photophysical characterization of the novel molecular photocatalyst [(tbbpy)(2)Ru(tpac)PdCl(2)](2+) RutpacPd (with tpac = tetrapyrido[3,2-a:2',3'-c:3 '',2 ''-h:2''',3'''-j]acridine) and its mononuclear building block. Furthermore, detailed photocatalytic activity measurements of RutpacPd are presented. The introduction of the tpac-ligand into the molecular framework offers a potential route to reduce the impact of water as compared to the well-studied class of RutpphzPd (with tpphz = tetrapyrido[3,2-a:2',3'-c:300,2 ''-h: 2''',3'''-j] phenazine) complexes. The distinct impact of water on the electron-transfer processes in tpphz-ligands stems from the possibility of water to form hydrogen bonds to the phenazine nitrogen atoms and will potentially reduced when replacing the phenazine by the acridine unit. The effect of this structural variation on the catalytic properties and the underlying ultrafast intramolecular charge transfer behavior will be discussed in detail. (C) 2011 Elsevier B. V. All rights reserved.
Keywords: Photocatalysis; Ultrafast dynamics; Molecular photocatalyst; Impact of water on the catalytic properties; Hydrogen

Synthesis and Properties of Organic Hexahalocerate(III) Salts - Pohako-Esko, Kaija; Wehner, Tobias; Schulz, Peter; Heinemann, Frank Wilhelm; Müller-Buschbaum, Klaus; Wasserscheid, Peter (European Journal of Inorganic Chemistry, 2016)
A series of hexahalocerate(III) salts with the general formula [cation](3)[CeHal(6)] have been prepared by dissolving anhydrous cerium trihalides in imidazolium halide ionic liquids. Complexes with different anions, [CeCl6](3-), [CeBr6](3-) and [CeBr3Cl3](3-), were synthesized and their cationic alkyl chains were varied. To confirm the structures of the prepared salts, X-ray crystallography was used to characterize [BMIM](3)[CeCl6]. Two different crystal structures were found: [BMIM](3)[CeCl6] and the linear coordination polymer [BMIM](x)[Ce(mu-Cl)(2)Cl-2(EtOH)(2)](x) containing coordinated solvent. All the synthesized compounds were characterized by DSC and TGA. The influence of the cationic and anionic structures on the melting points and decomposition temperatures is discussed. Furthermore, the Ce-containing salts [BMIM](3)[CeHal(6)] show interesting photoluminescence properties: intense Ce3+-based 5d-4f-centred emission from the soft UV-B region to the border of visible light is observed that is driven both by direct excitation of Ce3+ as well as by a sensitizer effect of the [BMIM](+) cation.
Keywords: Ionic liquids; Luminescence; Lanthanides; Cerium; Halides

Synthesis and Reactions of Pyridinethiones - Köditz, J.; Rudorf, W.-D.; Hartung, H; Heinemann, Frank Wilhelm (Justus Liebigs Annalen der Chemie, 1993)

Synthesis and Reactivity of a Cobalt-Supported Singlet Nitrene - Mao, Weiqing; Zhang, Zihan; Fehn, Dominik; Jannuzzi, Sergio A.V.; Heinemann, Frank Wilhelm; Scheurer, Andreas; van Gastel, Maurice; DeBeer, Serena; Munz, Dominik; Meyer, Karsten (Journal of the American Chemical Society, 2023)
The synthesis, characterization, and reactivity of a series of cobalt terminal imido complexes supported by an N-anchored tripodal tris(carbene) chelate is described, including a Co-supported singlet nitrene. Reaction of the CoI precursor [(TIMMNmes)CoI](PF6) (TIMMNmes = tris-[2-(3-mesityl-imidazolin-2-ylidene)-methyl]amine) with p-methoxyphenyl azide yields a CoIII imide [(TIMMNmes)CoIII(NAnisole)](PF6) (1). Treatment of 1 with 1 equiv of [FeCp2](PF6) at −35 °C affords a formal CoIV imido complex [(TIMMNmes)Co(NAnisole)](PF6)2 (2), which features a bent Co-N(imido)-C(Anisole) linkage. Subsequent one-electron oxidation of 2 with 1 equiv of AgPF6 provides access to the tricationic cobalt imido complex [(TIMMNmes)Co(NAnisole)](PF6)3 (3). All complexes were fully characterized, including single-crystal X-ray diffraction (SC-XRD) analyses, infrared (IR) vibrational, ultraviolet/visible (UV/vis) electronic absorption, multinuclear NMR, X-band electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and high-energy-resolution fluorescence-detected X-ray absorption spectroscopy (HERFD XAS). Quantum chemical calculations provide additional insight into the electronic structures of all compounds. The dicationic CoIV imido complex 2 exhibits a doublet ground state with considerable imidyl character as a result of covalent Co-NAnisole bonding. At room temperature, 2 readily converts to a CoII amine complex involving intramolecular C-H bond amination. Electronically, tricationic complex 3 can be understood as a singlet nitrene bound to CoIII with significant CoIV imidyl radical character. Verifying the pronounced electrophilicity, nucleophiles such as H2O and tBuNH2 add to 3─analogous to the parent free nitrene─in the para position of the aromatic substituent, thus, clearly corroborating singlet nitrene-type reactivity.
CRIS-Team Scopus Importer:2023-07-21

Synthesis and reactIVity of a terminal uranium(IV) sulfide supported by siloxide ligands - Andrez, Julie; Pecaut, Jacques; Scopelliti, Rosario; Kefalidis, Christos E.; Maron, Laurent; Rosenzweig, Michael; Meyer, Karsten; Mazzanti, Marinella (Chemical Science, 2016)
The reactions of the tetrasiloxide U(iii) complexes [U(OSi(OtBu)3)4K] and [U(OSi(OtBu)3)4][K18c6] with 0.5 equiv. of triphenylphosphine sulfide led to reductive S-transfer reactions, affording the U(iv) sulfide complexes [SU(OSi(OtBu)3)4K2]2, 1, and [SU(OSi(OtBu)3)4K22(μ-18c6)], 2, with concomitant formation of the U(iv) complex [U(OSi(OtBu)3)4]. Addition of 1 equiv. of 2.2.2-cryptand to complex 1 resulted in the isolation of a terminal sulfide complex, [SU(OSi(OtBu)3)4K][Kcryptand], 3. The crucial role of the K+ Lewis acid in these reductive sulfur transfer reactions was confirmed, since the formation of complex 3 from the reaction of the U(iii) complex [U(OSi(OtBu)3)4][Kcryptand] and 0.5 equiv. of PPh3S was not possible. Reactivity studies of the U(iv) sulfide complexes showed that the sulfide is easily transferred to CO2 and CS2 to afford S-functionalized products. Moreover, we have found that the sulfide provides a convenient precursor for the synthesis of the corresponding U(iv) hydrosulfide, [(SH)U(OSi(OtBu)3)4][K18c6], 5, after protonation with PyHCl. Finally, DFT calculations were performed to investigate the nature of the U-S bond in complexes 1, 3 and 5. Based on various analyses, triple-bond character was suggested for the U-S bond in complexes 1 and 3, while double-bond character was determined for the U-SH bond in complex 5.
CRIS-Team Scopus Importer:2020-09-14

Synthesis and Reactivity of Low-Valent f-Element Iodide Complexes with Neutral Iminophosphorane Ligands - Cheisson, Thibault; Ricard, Louis; Heinemann, Frank Wilhelm; Meyer, Karsten; Auffrant, Audrey; Nocton, Gregory (Inorganic Chemistry, 2018)
The coordination and reactivity of simple iodide salts of low-valent f elements [YbI2, SmI2, TmI2, and UI3(THF)4, where THF = tetrahydrofuran] with iminophosphorane (R3P=NR′) ligands are reported. The studied chelates were observed to adapt their geometry and effectively bind divalent ytterbium and samarium centers, as well as the trivalent uranium cation. The reactivity of the ytterbium adducts with benzophenone was found to be dependent on the steric demand of the supporting iminophosphorane ligand. In particular, a rare example of a stable charge-separated ketyl radical species is reported with ytterbium. Additionally, divalent thulium was observed to induce a reductive coupling at the ligand's central pyridine ring.
CRIS-Team Scopus Importer:2020-09-14

Synthesis and reactivity of new complexes containing the [Ru("S4")] fragment ["S4"2- = 1,2-bis(2-mercaptophenylthio)ethane(2-)] - Heinemann, Frank Wilhelm; et al. (Chemische Berichte, 1997)
Keywords: Ligand effects; Labile ruthenium-sulfur complexes; Structure-activity relationships; S2 complexes; Substitution reactions

Synthesis and redox properties of mixed-valent octanuclear iron defective hexacubanes and a (CaCl)-capped body-centered six-sided iron(III) polyhedron. - Heinemann, Frank Wilhelm; et al. (Angewandte Chemie International Edition, 2006)

Synthesis and structural characterization of a highly substituted triazine ring comprising a sterically flexible methylene linker and coordinating substituents - Werle, Christophe; Yin, Chih-Juo; Heinemann, Frank Wilhelm; Hauser, Christina; Meyer, Karsten (Tetrahedron Letters, 2017)
The efficient multi-step, large-scale synthesis, spectroscopic characterization and solid-state molecular structure of a new type of three-fold functionalized, sterically demanding triazine is reported. The aromatic heterocycle 6,6 ',6('')((1,3,5-triazine-2,4,6-triy1)tris(methylene))tris(2,4-di-tert-butylphenol) possesses three 2,4-di-tert-butylphenol synthons bound to the 1,3,5-triazine ring via synthetically challenging methylene linkages in the 2,4,6 positions. The key to success was found in the generation of a highly reactive imidate hydrochloride salt, namely ethyl 2-(3,5-di-tert-butyl-2-methoxyphenyl)acetimidate hydrochloride, that readily undergoes cyclotrimerization. The reported preparation opens new perspectives in the design and synthesis of novel triazine molecules bearing flexible and sterically demanding functionalized groups for various applications. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords: Triazine; Heterocycles; Cyclotrimerization; Imidates

Synthesis and Structural Characterization of a New Tetranuclear Macrocyclic Copper(I) Complex - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Anorganische und Allgemeine Chemie, 2003)
Keywords: Copper; Coordination chemistry; N-donor ligands; Macrocyclic ligands

Synthesis and structure of a my-(E)-vinylidene-bis[dimethylglyoximato(1-)-dimethylglyoximato(2-)-(triphenyl- phosphine)rhodate] complex: a vinylene-bridged dinuclear rhodium complex - Steinborn, Dirk; Aisa, A. M. A.; Heinemann, Frank Wilhelm; Lehmann, S.; et al. (Journal of Organometallic Chemistry, 1997)

Synthesis and structure of bis(thiomethyl)magnesium compounds [Mg(CH2SR)2(thf)3] (R=Me, Ph) – the first dimethylmagnesium compounds functionalized by a Lewis-basic heteroatom - Steinborn, Dirk; Rüffer, T.; Bruhn, C; Heinemann, Frank Wilhelm (Polyhedron, 1998)

Synthesis and Structure of High-Nuclearity Bimetallic Clusters containing Polycyanometallate Cores capped by [NiII(pyN4)] Fragments - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Anorganische und Allgemeine Chemie, 2003)
Keywords: Iron; Nickel; Magnetic properties; Tetrapodal pentadentate ligand; Polycyanometallates

Synthesis and Structure of (P,P-Diphenylphosphino)methyl lithium-tetrahydrofuran - Steinborn, Dirk; Neumann, O.; Weichmann, H.; Heinemann, Frank Wilhelm; Wagner, J.-P. (Polyhedron, 1998)

Synthesis and structure of self-complementary 2-metallacryptates and their linear or meandering infinite arrangements in the solid state - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2007)
Keywords: metallacryptate; coordination polymers; O ligands; X-ray diffraction; chirality

Synthesis and structures of a pincer-type rhodium(III) complex: Reactivity toward biomolecules - Milutinovic, Milan M.; Bogojeski, Jovana V.; Klisuric, Olivera; Scheurer, Andreas; Elmroth, Sofi K. C.; Bugarcic, Zivadin D. (Dalton Transactions, 2016)

Synthesis and structures of platina-ß-diketonato complexes of platina-ß-diketones; organometallic analogues of platinum blue complexes - Steinborn, Dirk; Gerisch, M.; Heinemann, Frank Wilhelm; Bruhn, C (Chemical Communications, 1997)

Synthesis and transition metal complexes of 3,3-bis(1-vinylimidazol-2-yl) propionic acid, a new N,N,O ligand suitable for copolymerisation - Peters, Liv; Tepedino, Fatima; Haas, Thomas; Heinemann, Frank Wilhelm; Wolf, Marion; Burzlaff, Nicolai (Inorganica Chimica Acta, 2011)
The new N,N,O heteroscorpionate ligand 3,3-bis(1-vinylimidazol-2-yl) propionic acid (Hbvip) (5) was synthesised in five steps starting from 1-vinylimidazole. This ligand is closely related to 3,3-bis(1-methylimidazol-2- yl)propionic acid (Hbmip), but contains two vinyl linker groups which can be used for radical-induced polymerisation reactions. The κ -N,N,O coordination behaviour of 5 was proven by the synthesis of the tricarbonyl complexes [Re(bvip)(CO) ] (6), [Mn(bvip)(CO) ] (7) and [Cu(bvip) ] (8). To obtain good yields of 6, it was synthesised in water instead of THF. The ligand as well as all three complexes were characterised by X-ray crystallography. Copolymerisation of 5 with pure methyl methacrylate (MMA) or a combination of MMA and ethylene glycol dimethacrylate (EGDMA) led to the solid phases P1 and P2. Polymer-bound rhenium and manganese tricarbonyl complexes could be obtained by the reaction of deprotonated P1 with [MBr(CO) ] (M = Re, Mn) and also by copolymerisation of 6 and 7 with MMA. In both cases, the facial tripodal binding behaviour was evidenced by IR spectra of the polymers. Furthermore, the content of metal incorporated in the polymers was determined by elemental analysis, AAS or ICP-OES measurements. Reaction of the deprotonated solid phase P1 with copper(II) chloride led to a blue solid-phase (P1-Cu). The UV-Vis absorption maximum of P1-Cu is found at 615 nm, which is almost identical to that found for 8. Thereby, it seems likely that P1 is flexible enough to form bisligand complexes with copper(II). This means that the copper centres act as a kind of crosslinking agents. In contrast, the heterogeneous reaction of P2 with copper(II) chloride yielded a lime green solid phase (P2-Cu). The bathochromic shift of the absorption maximum by 102 nm suggests one-sided bound copper centres. © 2011 Elsevier B.V. All rights reserved.

Synthesis and X-ray Crystal Structure of the Electron-Deficient Metal Carbonyl Cluster [Os3(CO)5(my3-H)(my-H)(my-PBut2)2(my-Ph2PCH2PPh2)]. - Heinemann, Frank Wilhelm; Böttcher, H. (Journal of Organometallic Chemistry, 1996)

Synthesis and X-ray structures of novel lead(1+) and indium(3+) phosphazenide complexes; Detailed 207Pb-NMR spectra of the 207Pb-Labelled dimeric lead(1+) species - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 1998)
Keywords: Indium(3+); 207Pb-NMR spectra; Organylphosphanylamide complexes; Lead(1+); Phosphazene

Synthesis, characterization and antitumor activity of polymeric copper(II) complexes with thiosemicarbazones of 3-methyl-5-oxo-1-phenyl-3-pyrazolin-4-carboxaldehyde and 5-oxo-3-phenyl-3-pyrazolin-4-carboxaldehyde - Leovac, Vukadin M.; Bogdanovic, Goran A.; Jovanovic, Ljiljana S.; Joksovic, Ljubinka; Markovic, Violeta; Joksovic, Milan D.; Dencic, Sonja Misirlic; Isakovic, Andelka; Markovic, Ivanka; Heinemann, Frank Wilhelm; Trifunovic, Srecko; Dalovic, Ivica (Journal of Inorganic Biochemistry, 2011)
New polymeric copper(II) complexes with two tridentate ONS thiosemicarbazone ligands containing substituted pyrazolone moiety were synthesized and characterized by means of spectroscopic, electrochemical and crystallographic techniques. While both ligands exist as different tautomers in the solid state and DMSO-d(6) solution, Cu(II) ion coordinates the ligands from the same tautomeric form with square-pyramidal geometry around each Cu atom. In the crystal structures, the copper(II) complex cation forms polymeric chains [Cu(L)Cl(+)](n) with a bridging chlorine atom. One of the complexes was found to have a significantly higher cytotoxic potential in comparison with cisplatin in inhibition of several cell lines (HL60, REH, C6, L929 and B16). The results obtained on the basis of flow cytometry indicated that apoptosis could be possible mechanism of cell death. (C) 2011 Elsevier Inc. All rights reserved.
Keywords: Copper(II) complexes; Pyrazolone; Thiosemicarbazone; X-ray structures; Electrochemistry; Cytotoxicity

Synthesis, Characterization, and Properties of Iron(II) Spin-Crossover Molecular Photoswitches Functioning at Room Temperature. - Mörtel, Max; Witt, Alexander; Heinemann, Frank Wilhelm; Bochmann, Sebastian; Bachmann, Julien; Khusniyarov, Marat (Inorganic Chemistry, 2017)
Spin-crossover molecular switches [FeII(H2B(pz)2)2L] (L = novel phenanthroline-based ligands featuring photochromic diarylethene units; pz = 1-pyrazolyl) were synthesized and thoroughly characterized by variable-temperature X-ray crystallography, Mössbauer spectroscopy, and magnetic measurements. The effect of substituents introduced into the phenanthroline backbone (L2) and into the photochromic diarylethene unit (L3) on photophysical properties of metal-free ligands and spin-crossover iron(II) complexes 2 and 3, respectively, were investigated in detail. Both ligands and complexes could be switched with light in solution at room temperature. The photocyclization of 2 was accompanied by a high-spin to low-spin photoconversion determined at 19%. The closed-ring isomers of L3 and 3 reveal the lifetimes in the range of minutes, whereas those of L2 and 2 are thermally stable for days in solutions at room temperature. The reversibility of the photoswitching can be improved by avoiding the photostationary states. Prospective introduction of anchoring groups to the phenanthroline backbone might allow the construction of chemisorbed self-assembled monolayers of spin-crossover species switchable with light at room temperatur

Synthesis, crystal and solution structures and antimicrobial screening of palladium(II) complexes with 2-(phenylselanylmethyl)oxolane and 2-(phenylselanylmethyl)oxane as ligands - Bugarcic, Zorica M.; Divac, Vera M.; Kostic, Marina D.; Jankovic, Nenad Z.; Heinemann, Frank Wilhelm; Radulovic, Niko S.; Stojanovic-Radic, Zorica Z. (Journal of Inorganic Biochemistry, 2015)
Two novel Pd(II) complexes with 2-(phenylselanylmethyl)oxolane and 2-(phenylselanylmethyl)oxane as ligands were synthesized. The crystal and molecular structure of the complexes has been determined by single crystal X-ray diffraction. It turned out for both complexes that the two ligands are coordinated to Pd via Se atoms in a trans-fashion and the other two trans-positions are occupied by Cl- ions. Detailed 1D- and 2D-NMR analyses revealed the existence of equilibrating trans-diastereomeric species differing in the configuration at four chiral centers (selenium and carbon) in the solution of the complexes. A computational study was also undertaken to assess the relative stabilities of the mentioned stereoisomeric species. The antimicrobial properties of the complexes were investigated against a series of human pathogenic bacterial and fungal strains. The complexes were shown to possess promising broad spectrum moderate antimicrobial activity that is more pronounced against fungal organisms. The noted activity could be completely attributed to the Pd(II) center, whereas the ligands probably mediate the transportation of a Pd(II) species across cell membranes. (C) 2014 Elsevier Inc. All rights reserved.
Keywords: Organoselenium chemistry; Ligands; Palladium; Antimicrobial activity

Synthesis, magnetic properties, and STM spectroscopy of an unprecedented octanuclear chloro-bridged nickel(II) double cubane. - Scheurer, Andreas; Gieb, Klaus; Alam, Mohammad S.; Heinemann, Frank Wilhelm; Saalfrank, Rolf; Kroener, Wolfgang; Petukhov, Konstantin; Stocker, Michael; Müller, Paul (Dalton Transactions, 2012)
Reaction of nickel(II) chloride hexahydrate with N-n-butyldiethanolamine H(2)L (3) in the presence of LiH in anhydrous THF leads to the formation of the unique octanuclear chloro-bridged nickel(II) double cubane [(Ni(II)(4)(μ(3)-OH)Cl(3)(HL)(3)μ(2)-Cl)(2)] (4) in 57% yield. According to single crystal X-ray structure analysis, complex 4·4CH(2)Cl(2) possesses a [(Ni(4)(μ(3)-OH)(μ(3)-O)(3)(OH)(3)(N)(3)(Cl)(3)μ(2)-Cl)(2)] core and crystallizes in the monoclinic space group P2(1)/c with a = 18.292(2), b = 19.8972(5), c = 23.295(2) Å, β = 98.408(6)°, V = 8387.3(8) Å(3), and four molecules in the unit cell. The analysis of the SQUID magnetic susceptibility data identified 4 as a weakly coupled dimer (J(1) = 14.5 K, J(2) = -0.6 K) with a ground state of S = 0, resulting from two S = 4 states of each Ni(4) subunits. Although complex 4 does not show an ac out-of-phase signal in a zero dc field at temperatures of 1.8 K and higher, low-temperature magnetization measurements revealed that complex 4 is a single-molecule magnet and shows hysteretic magnetization characteristics with typical temperature and sweep-rate dependencies. The eye-catching feature of complex 4 is the presence of two different blocking temperatures (0.9 K around zero field and 1.3 K at higher fields). The origin of this highly unusual behavior can be assigned to the dimer-nature of the interaction between the two S = 4 units. Furthermore STM and current imaging tunnelling spectroscopy (CITS) were performed on aggregates of 4 drop-coated on highly oriented pyrolytic graphite (HOPG) surfaces. CITS measurements show a strong contrast in the area of the nickel centers and a HOMO-LUMO gap of approximately 0.8 V.

Synthesis, magnetic properties, and STM spectroscopy of cobalt(II) Cubanes [Co(II) (4)(Cl)(4)(HL)(4)]. - Scheurer, Andreas; Ako, Ayuk Manase; Saalfrank, Rolf; Heinemann, Frank Wilhelm; Hampel, Frank; Petukhov, Konstantin; Gieb, Klaus; Stocker, Michael; Müller, Paul (Chemistry - A European Journal, 2010)
Reaction of cobalt(II) chloride hexahydrate with N-substituted diethanolamines H(2)L(2-4) (3) in the presence of LiH in anhydrous THF leads under anaerobic conditions to the formation of three isostructural tetranuclear cobalt(II) complexes [Co(II) (4)(Cl)(4)(HL(2-4))(4)] (4) with a [Co(4)(mu(3)-O)(4)](4+) cubane core. According to X-ray structural analyses, the complexes 4 a,c crystallize in the tetragonal space group I4(1)/a, whereas for complex 4 b the tetragonal space group Par 4 was found. In the solid state the orientation of the cubane cores and the formation of a 3D framework were controlled by the ligand substituents of the cobalt(II) cubanes 4. This also allowed detailed magnetic investigations on single crystals. The analysis of the SQUID magnetic susceptibility data for 4 a gave intramolecular ferromagnetic couplings of the cobalt(II) ions (J(1) approximately 20.4 K, J(2) approximately 7.6 K), resulting in an S=6 ground-state multiplet. The anisotropy was found to be of the easy-axis type (D=-1.55 K) with a resulting anisotropy barrier of Delta approximately 55.8 K. Two-dimensional electron-gas (2DEG) Hall magnetization measurements revealed that complex 4 a is a single-molecule magnet and shows hysteretic magnetization characteristics with typical temperature and sweep-rate dependencies below a blocking temperature of about 4.4 K. The hysteresis loops collapse at zero field owing to fast quantum tunneling of the magnetization (QTM). The structural and electronic properties of cobalt(II) cubane 4 a, deposited on a highly oriented pyrolytic graphite (HOPG) surface, were investigated by means of STM and current imaging tunneling spectroscopy (CITS) at RT and standard atmospheric pressure. In CITS measurements the rather large contrast found at the expected locations of the metal centers of the molecules indicated the presence of a strongly localized LUMO.

Synthesis, Magnetic Properties, and X-ray Spectroscopy of Divalent Cobalt(II) and Nickel(II) Cubanes [M4II(HL2)4(OAc)4] - Scheurer, Andreas; Korzekwa, Jana; Nakajima, Takayuki; Hampel, Frank; Buling, Anna; Derks, Christine; Neumann, Manfred; Joly, Loic; Petukhov, Konstantin; Gieb, Klaus; Müller, Paul; Kuepper, Karsten; et al. (European Journal of Inorganic Chemistry, 2015)
Under anaerobic conditions, the reactions of cobalt(II) and nickel(II) acetate tetrahydrate with 2,6-pyridinedimethanol (H2L2, 3) in anhydrous acetonitrile afforded two tetranuclear metal(II) complexes [MII4(HL2)4(OAc)4] (4; MII = Co2+, Ni2+) with a [M4(μ3-O)4]4+ cubane core. X-ray structural analyses revealed that both MII cubanes 4a·2CH3OH and 4b·2CH3OH are isostructural and crystallize in the tetragonal space group I41/acd with eight molecules in the unit cell. In the solid state, the orientation of the cubane cores of 4 and the formation of a 3D framework were controlled by π–π interactions as well as intra- and intermolecular O–H···O hydrogen bonds. Variable-temperature magnetic susceptibility measurements revealed that the cubanes 4 show a ferrimagnetic coupling scheme that leads to a diamagnetic ground state for both complexes. Core-level X-ray photoelectron spectroscopy confirmed that the Co and Ni ions in 4a and 4b are in a divalent state. X-ray magnetic circular dichroism was performed to extract the spin and orbital contributions to the Co and Ni magnetic moments. We compared the experimental results of the local electronic structures around the Co2+ ions in 4a and the Ni2+ ions in 4b with charge-transfer multiplet simulations.
Keywords: N; O ligands; Cubanes; Magnetic properties; X-ray absorption spectroscopy; X-ray photoelectron spectroscopy

Synthesis of an All-Ferric Cuboidal Iron–Sulfur Cluster [FeIII4S4(SAr)4] - Moula, Golam; Matsumoto, Tsuyoshi; Miehlich, Matthias; Meyer, Karsten; Tatsumi, Kazuyuki (Angewandte Chemie International Edition, 2018)
An unprecedented, super oxidized all-ferric iron–sulfur cubanoid cluster with all terminal thiolates, Fe4S4(STbt)4 (3) [Tbt=2,4,6-trisbis(trimethylsilyl)methylphenyl], has been isolated from the reaction of the bis-thiolate complex Fe(STbt)2 (2) with elemental sulfur. This cluster 3 has been characterized by X-ray crystallography, zero-field 57Fe Mössbauer spectroscopy, cyclic voltammetry, and other relevant physico-chemical methods. Based on all the data, the electronic ground state of the cluster has been assigned to be Stot=0.
CRIS-Team Scopus Importer:2020-09-14
Keywords: high oxidation states; iron–sulfur cubane cluster; magnetism; Mössbauer spectroscopy

Synthesis of a Nitrogenase P-N-Cluster Model with [Fe8S7(mu-S-thiolate)(2)] Core from the All-Ferric [Fe4S4(S-thiolate)(4)] Cubane Synthon - Moula, Golam; Nagasaki, Ayaka; Matsumoto, Tsuyoshi; Miehlich, Matthias; Meyer, Karsten; Cramer, Roger E.; Tatsumi, Kazuyuki (Angewandte Chemie International Edition, 2021)
Constructing synthetic models of the nitrogenase P-N-cluster has been a long-standing synthetic challenge. Here, we report an optimal nitrogenase P-N-cluster model [(TbtS)(OEt2)Fe4S3(2)(mu-STbt)(2)(mu(6)-S)] (2) [Tbt=2,4,6-trisbis(trimethylsilyl)methylphenyl] that is the closest synthetic mimic constructed to date. Of note is that two thiolate ligands and one hexacoordinated sulfide are connecting the two Fe4S3 incomplete cubanes similar to the native P-N-cluster, which has never been achieved. Cluster 2 has been characterized by X-ray crystallography and relevant physico-chemical methods. The variable temperature magnetic moments of 2 indicate a singlet ground state (S=0). The Mossbauer spectrum of 2 exhibits two doublets with an intensity ratio of 3:1, which suggests the presence of two types of iron sites. The synthetic pathway of the cluster 2 could indicate the native P-N-cluster maturation process as it has been achieved from the Fe4S4 cubane Fe4S4(STbt)(4) (1).
CRIS-Team WoS Importer:2021-06-18

Synthesis of bis(imino)pyridine iron amide and ammonia compounds from an N-H transfer agent - Bowman, A. C.; Bart, Suzanne C.; Heinemann, Frank Wilhelm; Meyer, Karsten; Chirik, P. J. (Inorganic Chemistry, 2009)
Addition of the [NH] transfer reagent Hdbabh (dbabh = 2,3:5,6-dibenzo-7- azabicyelo[2.2.1]hepta-2,5-diene) to the bis(imino)pyr-idine iron bis(dinitrogen) complex, ( PDI)Fe(N ) ( PDI = 2,6-(2,6 Pr C H N=CMe) C H N), furnished the corresponding iron amide and ammonia compounds, resulting from cleavage of the strained amine. Isotopic labeling studies support N-H bond activation by a transient, parent imide, [( PDI)FeNH]. © 2009 American Chemical Society.

Synthesis of Camphor-Derived Bis(pyrazolylpyridine) Rhodium(III) Complexes: Structure-Reactivity Relationships and Biological Activity - Petrovic, Angelina; Milutinovic, Milan M.; Petri, Edward T.; Zivanovic, Marko; Milivojevic, Nevena; Puchta, Ralph; Scheurer, Andreas; Korzekwa, Jana; Klisuric, Olivera R.; Bogojeski, Jovana (Inorganic Chemistry, 2019)
Two novel rhodium(III) complexes, namely, [Rh III (X)Cl 3 ] (X = 2 2,6-bis((4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-1H-4,7-methanoindazol-3-yl)pyridine or 2,6-bis((4S,7R)-1,7,8,8-tetramethyl-4,5,6,7-tetrahydro-1H-4,7-methanoindazol-3-yl)pyridine), were synthesized from camphor derivatives of a bis(pyrazolylpyridine), tridentate nitrogen-donor chelate system, giving [Rh III (H 2 L∗)Cl 3 ] (1a) and [Rh III (Me 2 L∗)Cl 3 ] (1b). A rhodium(III) terpyridine (terpy) ligand complex, [Rh III (terpy)Cl 3 ] (1c), was also synthesized. By single-crystal X-ray analysis, 1b crystallizes in an orthorhombic P2 1 2 1 2 1 system, with two molecules in the asymmetric unit. Tridentate coordination by the N,N,N-donor localizes the central nitrogen atom close to the rhodium(III) center. Compounds 1a and 1b were reactive toward l-methionine (l-Met), guanosine-5′-monophosphate (5′-GMP), and glutathione (GSH), with an order of reactivity of 5′-GMP > GSH > l-Met. The order of reactivity of the Rh III complexes was: 1b> 1a > 1c. The Rh III complexes showed affinity for calf thymus DNA and bovine serum albumin by UV-vis and emission spectral studies. Furthermore, 1b showed significant in vitro cytotoxicity against human epithelial colorectal carcinoma cells. Since the Rh III complexes have similar coordination modes, stability differences were evaluated by density functional theory (DFT) calculations (B3LYP(CPCM)/LANL2DZp). With (H 2 L∗) and (terpy) as model ligands, DFT calculations suggest that both tridentate ligand systems have similar stability. In addition, molecular docking suggests that all test compounds have affinity for the minor groove of DNA, while 1b and 1c have potential for DNA intercalation.
CRIS-Team Scopus Importer:2019-05-09

Synthesis of [Cp'Fe(η3-BH4)] and its conversion to [Cp'FeBH2]3 - Maekawa, Miyuki; Daniliuc, Constantin G.; Jones, Peter G.; Hohenberger, Johannes; Sutter, Jörg; Meyer, Karsten; Walter, Marc D. (European Journal of Inorganic Chemistry, 2013)
Salt metathesis of [Cp'FeI] [1, Cp' = η-1,2,4- (MeC)CH] and NaBH (2 equiv.) in tetrahydrofuran yields the low-spin iron complex [Cp'Fe(ηBH)] (2), which is thermally unstable and degrades slowly to the trimeric complex [Cp'FeBH] (3) and H. Both molecules have been fully characterized by various spectroscopic techniques. An X-ray structure analysis of 3 confirms its nature and reveals rather long B-B distances of 1.883(9) Å. DFT methods in combination with three complementary approaches [Wiberg bond indices (WBI), atoms in molecules (AIM) and compliance constants] have been used to explain the bonding in these iron(II) complexes. All methods predict a weak bonding interaction between the boron atoms in 3. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Keywords: Iron; Hydride ligands; Sandwich complexes; Density functional calculations; Boranes; Borohydrides

Synthesis of differently substituted tacn-based ligands: Towards the control of solubility and electronic and steric properties of uranium coordination complexes - Nizovtsev, Alexey; Scheurer, Andreas; Kosog, Boris; Heinemann, Frank Wilhelm; Meyer, Karsten (European Journal of Inorganic Chemistry, 2013)
Starting from phenols ArOH (5) and the anisole derivative 3,5-di-tert-butyl-2-methoxybenzyl bromide (13), a series of new tacn-based ligands (ArOR)tacn (2) have been synthesized with substituents of varying bulkiness and electronic nature at the ortho and para positions with respect to the oxygen coordination site. It was observed that these groups not only determine the steric shielding and solubility properties of 2, but also deactivate the reactivity of the phenols in the modified Mannich reaction when electron-withdrawing groups are introduced at the para position in 5. Treatment of the ligands with UCl in thf led to the isolation of four uranium(IV) chloro complexes [( ArO)tacnUCl] (14), which were characterized by different spectroscopic and physical methods (e.g., H NMR, UV/Vis, SQUID), corroborating the +4 oxidation state in 14. Single-crystal X-ray structure analyses revealed that 14a·CH Cl·CHCN and 14b·1.25CH Cl crystallize in the chiral, orthorhombic space group P222 [a = 24.934(3), b = 27.941(3), c = 9.045(1) Å, V = 6302(2) Å, Z = 4] and the chiral, hexagonal space group P6 [a = 22.097(3), c = 17.941(2) Å, V = 7587(2) Å, Z = 4], respectively. Interestingly, complexes 14a,b self-organize in the solid state into homochiral 1D polymeric superstructures as a result of weak intermolecular C-H⋯Cl contacts. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Rationally Halogenated Buckybowls by Chemoselective Aromatic C-F Bond Activation. - Papaianina, Olena; Akhmetov, Vladimir A.; Goryunkov, Alexey A.; Hampel, Frank; Heinemann, Frank Wilhelm; Amsharov, Konstantin (Angewandte Chemie-International Edition, 2017)
Halogenated buckybowls or bowl-shaped polycyclic aromatic hydrocarbons (BS-PAHs) are key building blocks for the "bottom-up" synthesis of various carbon-based nanomaterials with outstanding potential in different fields of technology. The current state of the art provides quite a limited number of synthetic pathways to BS-PAHs; moreover, none of these approaches show high selectivity and tolerance of functional groups. Herein we demonstrate an effective route to BS-PAHs that includes directed intramolecular aryl-aryl coupling through C-F bond activation. The coupling conditions were found to be completely tolerant toward aromatic C-Br and C-Cl bonds, thus allowing the facile synthesis of rationally halogenated buckybowls with an unprecedented level of selectivity. This finding opens the way to functionalized BS-PAH systems that cannot be obtained by alternative methods.

Synthesis of uranium(VI) terminal oxo complexes: Molecular geometry driven by the inverse trans -influence - Kosog, Boris; la Pierre, Henry Storms; Heinemann, Frank Wilhelm; Liddle, Stephen T.; Meyer, Karsten (Journal of the American Chemical Society, 2012)
Oxidation of our previously reported uranium(V) oxo complexes, supported by the chelating ( ArO) tacn ligand system (R = tert-butyl (t-Bu), 1-t-Bu; R = 1-adamantyl (Ad), 1-Ad), yields terminal uranium(VI) oxo complexes [(( ArO) tacn)U(VI)(O)]SbF (R = t-Bu, 2-t-Bu; R = Ad, 2-Ad). These complexes differ in their molecular geometry in that 2-t-Bu possesses pseudo-C symmetry in solution and solid state as the terminal oxo ligand lies in the equatorial plane (as defined by the three aryloxide arms of the ligand) in order to accommodate the thermodynamic preference of high-valent uranium oxo complexes to have a δ- and π-donating ligand trans to the oxo (vis-à-vis the ubiquity of the linear UO moiety). The distortion of the ligand - which stands in contrast to all other complexes of uranium supported by the ( ArO) tacn ligand, including 2-Ad - is most clearly seen in the structures of 2-t-Bu, [(( ArO) tacn)U(VI)(O) ]SbF , and 3-t-Bu, [(( ArO) tacn)U(VI)(O) (OC(O) CF ) ]. The solid-state structure of 3-t-Bu reveals that the trans U-O bond length is shortened by 0.1 Å in comparison to the cis U-O bonds and the trans U-O-C angle is linearized (157.67° versus 147.85° and 130.03°). Remarkably, the minor modification of the ligand to have Ad groups at the ortho positions of the aryloxide arms is sufficient to stabilize a C -symmetric terminal uranium(VI) oxo complex (2-Ad) without a ligand trans to the oxo. These experimental results were reproduced in DFT calculations and allow the qualitative bracketing of the relative thermodynamic stabilization afforded by the inverse trans-influence as ∼6 kcal mol . © 2012 American Chemical Society.

Synthesis, reactivity, and structure of strictly homologous 18 and 19 valence electron iron nitrosyl complexes. - Sellmann, Dieter; Heinemann, Frank Wilhelm; Heß, Bernd Artur; et al. (Chemistry - A European Journal, 2001)
The 18 and 19 valence electron (VE) nitrosyl complexes [Fe(NO)('pyS4')]BF4 ([1]BF4) and [Fe(NO)('pyS4')] (2) have been synthesized from [Fe('pyS4')]x ('pyS4'(2-) = 2,6-bis(2-mercaptophenylthiomethyl)pyridine(2-)) and either NOBF4 or NO gas. Complex [1]BF4 was also obtained from [Fe(CO)('pyS4')] and NOBF4. The cation [1]+ is reversibly reduced to give 2. Oxidation of 2 by [Cp2Fe]PF6 afforded [Fe(NO)('pyS4')]PF6 ([1]PF6). The molecular structures of [1]PF6 and 2 were determined by X-ray crystallography. They demonstrate that addition of one electron to [1]+ causes a significant elongation of the Fe-donor atom bonds and a bending of the FeNO angle. Density functional calculations show that the unpaired electron in 2 occupies an orbital, which is antibonding with respect to all Fe-ligand interactions. As expected from qualitative Molecular Orbital (MO) theory, it has a large contribution from a pi* type NO orbital. The nu(NO) frequency decreases from 1893 cm(-1) in [1]BF4 to 1648 cm(-1) in 2 (in KBr). The antibonding character of the unpaired electron explains the ready reaction of 2 with excess NO to give [Fe(NO)2('pyS4')] (3), the facile NO/CO exchange of 2 to afford [Fe(CO)('pyS4')], and the easy oxidation of 2 to [1]+.
UnivIS-Import:2017-03-24:Pub.2001.forsch.sonder.sfb583.synthe
Keywords: Density functional calculations; Iron; Nitrosyl complexes; S ligands; Structure elucidation

Synthesis, redox, and magnetic properties of a neutral, mixed-valent heptanuclear manganese wheel with S = 27/2 high-spin ground state. - Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry, 2007)
Reaction of lithium tetrachloromanganate(II) with N-n-butyldiethanolamine H2L3 (3) in the presence of LiH leads to the formation of wheel-shaped, mixed-valent heptanuclear, neutral complex MnII subset[MnII2MnIII4Cl6(L3)6] (4). The manganese wheel crystallizes in the triclinic space group P as 4.2CHCl3 or 4.3THF when either diethyl ether or n-pentane was allowed to diffuse into solutions of 4 in chloroform or tetrahydrofuran. The oxidation states of each manganese ion in 4.2CHCl3 or 4.3THF were assigned on the basis of detailed symmetry, bond length, and charge considerations, as well as by the Jahn-Teller axial elongation observed for the manganese(III) ions, and were further supported by cyclic voltammetry. The analysis of the SQUID magnetic susceptibility data for complex 4.2CHCl3 showed that the intramolecular magnetic coupling of the manganese(II,III) ions is dominated by ferromagnetic exchange interactions. This results in an S = 27/2 ground-state multiplet at low magnetic field. At fields higher than 0.68 T, the energetically lowest state is given by the mS = 31/2 component of the S = 31/2 multiplet due to the Zeeman effect. The ligand-field-splitting parameters were determined by anisotropy SQUID measurements on single crystalline samples along the crystallographic x, y, and z axes (D = -0.055 K, E = 6.6 mK) and by high-frequency electron spin resonance measurements on a polycrystalline powder of 4.2CHCl3 (D = -0.068 K, E = 9.7 mK). The resulting barrier height for magnetization reversal amounts to U approximately 10 K. Finally, 2DEG Hall magnetization measurements revealed that 4.2CHCl3 shows single-molecule magnet behavior up to the blocking temperature of about 0.6 K with closely spaced steps in the hysteresis because of the quantum tunneling of the magnetization.

Synthesis, spectroscopy, X-ray crystal structure, and DFT studies on a platinum(II) Schiff-base complex - Akbari, Alireza; Ahmadi, Mehdi; Takjoo, Reza; Heinemann, Frank Wilhelm (Journal of Coordination Chemistry, 2012)
[PtCl2(SMe2)(2)] reacts with (N,N'-bis(salicylidene)-1,2-cyclohexanediamine) to give (N,N'-bis(salicylidene)cyclohexane-1,2-diamine)platinum(II). The complex has been characterized by elemental analysis, infrared (IR), UV-Vis, and single-crystal X-ray diffraction. Pt(II) is in a square-planar environment, coordinated by a chelating N2O2 donor. Density functional theory (DFT) calculations such as geometry optimization, vibrational frequency, electronic properties, and natural bond orbital (NBO) have been performed for the platinum compound using the OLYP method at TZP(6-311G*) basis set. The optimization calculation shows that the geometry parameters can be reproduced with the OLYP/TZP basis set. Experimental IR frequencies and calculated vibrational frequencies support each other. Time-dependent DFT has been used for absorption wavelengths and results were compared with experimental data. Moreover, NBO analysis has been performed.
Keywords: Platinum(II) complex; Crystal structure; Square-planar; DFT

Synthesis, structure, and dynamics of six-membered metallacoronands and metallodendrimers of iron and indium - Saalfrank, Rolf; Deutscher, Christian; Maid, Harald; Ako, Ayuk Manase; Sperner, Stefan; Nakajima, Takayuki; Bauer, Walter; Hampel, Frank; Heß, Bernd Artur; van Eikema Hommes, Nico; Puchta, Ralph; Heinemann, Frank Wilhelm (Chemistry - A European Journal, 2004)
In the reaction of the N-substituted diethanolamines (H2L1-3) (1-3) with calcium hydride followed by addition of iron(m) or indium(m) chloride, the iron wheels [Fe6Cl6(L-1)(6)] (4) and [Fe6Cl6(L-2)(6)] (6) or indium wheels [In6Cl6(L-1)(6)] (5), [In6Cl6(L-2)(6)] (8) and [In6Cl6(L-3)(6)] (9) were formed in excellent yields. Exchange of the chloride ions of 6 by thiocyanate ions afforded [Fe-6(SCN)(6)(L-2)(6)] (7). Whereas the structures of 4, 5 and 7 were determined unequivocally by single-crystal X-ray analyses, complexes 8 and 9 were characterised by NMR spectroscopy. Contrary to what is normally presumed, the scaffolds of six-membered metallic wheels are not generally rigid, but rather undergo nondissociative topomerisation processes. This was shown by variable temperature (VT) H-1 NMR spectroscopy for the indium wheel [In6Cl6(L-1)(6)] (5) and is highlighted for the enantiotopomerisation of one indium centre 1/6[S-6-5] reversible arrow 1/6[S-6-5']. The self-assembly of metallic wheels, starting from diethanolamine dendrons, is an efficient strategy for the convergent synthesis of metallodendrimers.
Keywords: dendrimers; density functional calculation; indium; iron; NMR spectroscopy; supramolecular chemistry

Synthesis, structure, and hydrolytic reaction of trans-dichlorobis(diethanolamine-N)palladium(II) with N-acetylated L-histidylglycine dipeptide - Heinemann, Frank Wilhelm; et al. (Bioorganic Chemistry, 2006)
The reaction of PdCl2, or K2PdCl4, with diethanolamine (DEA), in the molar ratio 1:2, affords the trans-[PdCl2(DEA)(2)] complex. X-ray structure analysis of this complex confirmed the formation of the trans-isomer. The complex crystallizes in the space group P4(2)bc. The central Pd(II) ion is coordinated in an almost ideal square-planar fashion with a small deformation of the Cl-Pd-Cl angle (175.6(7)degrees) due to N-(HCl)-Cl-... hydrogen bonding. The N-H group participates in a bifurcated interaction with the two symmetry related Cl- anions. The hydroxyl groups of the diethanolamine ligand form very strong hydrogen bonds between the complex units, thus leading to infinite zigzag (O-(HO)-O-...-(HO)-O-...-H (..)) chains in the crystal packing. The complex units are further connected by weaker intermolecular hydrogen bonds of the N-(HCl)-Cl-... type in a way to form layers parallel to the crystallographic (001) plane. The reaction between the trans[PdCl2(DEA)(2)] or trans-[Pd(H2O)(2)(DEA)(2)](2+) complex and MeCOHis-Gly dipeptide at 1.5 1 < pH < 2.0 and at 25 degrees C leads to the regioselective cleavage of the amide bond involving the carboxylic group of the histidine. The cleavage of the substrate was fast and went almost to completion within less than one hour, (c) 2006 Elsevier Inc. All rights reserved.
Keywords: palladium(II) complexes; crystal structure; catalysts; histidylglycine; hydrolysis

Synthesis, structure, and properties of osmium complexes containing [Os(′S4′)] and [Os(′S2′)2] fragments (′S4′2- = 1,2-bis(2-mercaptophenylthio)-ethane(2-), ′S2′2- = 1,2-benzenedithiolate) - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 1998)
Keywords: P ligands; Osmium; Solvent effects; S ligands

Synthesis, structure, and reactivity of an iron(V) nitride - Scepaniak, Jeremiah J.; Vogel, Carola; Khusniyarov, Marat; Heinemann, Frank Wilhelm; Meyer, Karsten; Smith, Jeremy M. (Science, 2011)
Despite being implicated as important intermediates, iron(V) compounds have proven very challenging to isolate and characterize. Here, we report the preparation of the iron(V) nitrido complex, [PhB( BuIm) Fe ≡N]BAr (PhB( BuIm) = phenyltris(3-tert-butylimidazol-2-ylidene)borato, BAr = B(3,5-(CF ) C H ) ), by one electron oxidation of the iron(IV) nitrido precursor. Single-crystal x-ray diffraction of the iron(V) complex reveals a four-coordinate metal ion with a terminal nitrido ligand. Mößbauer and electron paramagnetic resonance spectroscopic characterization, supported by electronic structure calculations, provide evidence for a d iron(V) metal center in a low spin (S = 1/2) electron configuration. Low-temperature reaction of the iron(V) nitrido complex with water under reducing conditions leads to high yields of ammonia with concomitant formation of an iron(II) species.

Synthesis, structure and reactivity of complexes containing [M(S 2)2] fragments (M = Ru, Os; (S2)2- = 1,2-benzenedithiolate (2-)) - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 2004)
Keywords: Osmium; S Ligands; Ruthenium

Synthesis, Structure, and Reactivity of Ruthenium and Osmium Nitrido Complexes with 1,2-Benzenedithiolate Ligands: N- versus S-Alkylation. - Sellmann, Dieter; Wemple, Michael; Donaubauer, Wolfgang; Heinemann, Frank Wilhelm (Inorganic Chemistry, 1997)
The reactivity of the nitrido complexes (N(n)Bu(4))[Ru(N)(S(2)C(6)H(4))(2)] (1) and (N(n)Bu(4))[Os(N)(S(2)C(6)H(4))(2)] (2) (C(6)H(4)(SH)(2) = 1,2-benzenedithiol) toward electrophiles, R(+) (R = Me, Et, Ph(3)C), is described. While 1 yielded intractable mixtures of products, 2 could be cleanly alkylated. The synthesis of 1 has been reported previously (Z.Naturforsch. 1987, 42B, 341); complex 2 can be synthesized by treating (N(n)Bu(4))[Os(N)Cl(4)] with deprotonated 1,2-benzenedithiol in acetone/MeOH at 0 degrees C. Complexes 1 and 2 are isostructural and crystallize in the orthorhombic space group Pna2(1), Z = 8, with a = 36.881(6) Å, b = 9.402(2) Å, and c = 17.652(2) Å for 1 and a = 37.042(4) Å, b = 9.375(2) Å, and c = 17.671(2) Å for 2. The anions of both compounds consist of a five-coordinate mononuclear center with a distorted square-pyramidal geometry; a terminal nitrido ligand occupies the apical position and two chelating (S(2)C(6)H(4))(2)(-) ligands form the basal plane. Treatment of 2 with R(3)OBF(4) in CH(2)Cl(2) yields [Os(N)(S(2)C(6)H(4))(SC(6)H(4)SR)] (R = Me, 3; R = Et, 4) where one thiolate donor is alkylated. Alkylation of the sulfur of the 1,2-benzenedithiolate ligand was confirmed by NMR spectroscopy and X-ray crystallography (for 3). Complex 3.CH(2)Cl(2) crystallizes in the orthorhombic space group P2(1)2(1)2(1), Z = 4, with a = 8.551(1) Å, b = 10.772(2) Å, and c = 19.716(3) Å. In contrast, treatment of 2 with Ph(3)CPF(6) in CH(2)Cl(2) yields [Os(NCPh(3))(S(2)C(6)H(4))(2)] (5), whose (1)H and (13)C NMR spectra indicate that the terminal nitride is the site of electrophilic attack. X-ray crystallography further confirms the alkylation at the nitrogen atom; complex 5 crystallizes in the triclinic space group P&onemacr;, Z = 2, with a = 9.338(8) Å, b = 10.001(3) Å, c = 16.280(6) Å, alpha = 75.88(3) degrees, beta = 74.29(6) degrees, and gamma = 69.55(5) degrees.

Synthesis, structure and reactivity of sulfur-rich [Fe(L-1)(L-2)('tpS(4)')] complexes with rigid [Fe('tpS(4)'] cores and sigma-pi Co-ligands ('tpS(4)'(2-)=1,2-bis(2-mercaptophenylthio)phenylene(2-); L-1, L-2=CO, PR3, NO) - Sellmann, Dieter; Blum, David; Heinemann, Frank Wilhelm; Sutter, Jörg (European Journal of Inorganic Chemistry, 2003)
Optimisation of synthesis and purification steps has made the new ligand 'tPS(4)'(2-) available in preparative amounts. Treatment of FeCl(2)(.)4H(2)O with 'tPS(4)'-Li-2 or 'tPS(4)'-Na-2 yielded [Fe('tPS(4)')] (1), which in the solid state and in the absence of co-ligands probably trimerises to give paramagnetic [Fe('tPS(4)')](3). The [Fe('tPS(4)')] fragment displays helical coordination of the 'tPS(4)'(2-) ligand and binds sigma-pi ligands such as CO, NO and phosphanes to give diamagnetic 18-valence-electron complexes of general formula [Fe(L-1)(L-2) ('tPS(4)')]The cis-dicarbonyl complex [Fe(CO)(2)CtPS(4)')1 (2) is labile and readily dissociates CO to give dinuclear [Fe(CO)('tPS(4)')](2) (3). Simultaneous coordination of CO and phosphanes yielded [Fe(CO)(PR3)('tPS(4)')] with R = Me (4), Et (5), Pr (6) and Bu (7), but it proved impossible to obtain analogous complexes with bulky PPh3 or PCY3 ligands. Bis(phosphane) complexes could be obtained only with PMe3 and the bidentate dppe, which yielded [Fe(PMe3)(2)('tPS(4)')] (8) and [Fe(dppe)('tPS4')] (11). Alkylphosphanes with longer alkyl substituents, such as PnPr(3) and PnBu(3), gave the labile derivatives [Fe(PR3)(2)-('tPS(4)')] with R = nPr (9) and nBu (10). Complexes 9 and 10 reversibly dissociate one PR3 ligand, yielding diamagnetic [Fe(PR3)(WtPS(4)')] fragments. These findings explain the decisive and hitherto inexplicable influence of PPr3 and PBu3 ligands upon the stabilisation of N2H2 in the diazene complexes [mu-N2H2Fe(PR3)('tpS(4)')(2)] with R = Pr, Bu. Treatment of [Fe('tPS(4)')] (1) or [Fe(CO)('tPS(4)')](2) (3) with NO or NO+ yielded [Fe(NO)(2)('tPS(4)')] (12). The molecular structures of 3, 4, 7 and 8 were determined by X-ray structure analysis. Spectroscopic and structural results indicate that the differences in reactivity between [Fe(L-1)(L-2) ('tPS(4)')] and homologous [Fe(L-1)(L-2)('S-4')] complexes can be traced back to subtle electronic and structural effects. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003
Keywords: helical structures; iron; S ligands

Synthesis, structure and reactivity of sulfur-rich [Fe(L1)(L2)("tpS4")] complexes with rigid [Fe("tpS4")] cores and σ-π co-ligands ("tpS4"2- = 1,2-bis(2-mercaptophenylthio)phenylene(2-); L1, L2 = CO, PR3, NO). - Sellmann, Dieter; Blum, David; Heinemann, Frank Wilhelm; Sutter, Jörg (European Journal of Inorganic Chemistry, 2003)
Optimization of synthesis and purifn. steps has made the new ligand tpS42- available in preparative amts. Treatment of FeCl2·4H2O with tpS4-Li2 or tpS4-Na2 yielded [Fe(tpS4)] (1), which in the solid state and in the absence of co-ligands probably trimerizes to give paramagnetic [Fe(tpS4)]3. The [Fe(tpS4)] fragment displays helical coordination of the tpS42- ligand and binds σ-π ligands CO, NO and phosphines to give diamagnetic 18-valence-electron [Fe(L1)(L2)(tpS4)]. The cis-dicarbonyl complex [Fe(CO)2(tpS4)] (2) is labile and readily dissocs. CO to give dinuclear [Fe(CO)(tpS4)]2 (3). Simultaneous coordination of CO and phosphines yielded [Fe(CO)(PR3)(tpS4)] with R = Me (4), Et (5), Pr (6) and Bu (7), but no reaction occurred with bulky PPh3 or PCy3 ligands. Bis(phosphine) complexes could be obtained only with PMe3 and the bidentate dppe, which yielded [Fe(PMe3)2(tpS4)] (8) and [Fe(dppe)(tpS4)] (11). Alkylphosphines with longer alkyl substituents, such as PPr3 and PBu3, gave the labile derivs. [Fe(PR3)2(tpS4)] with R = Pr (9) and Bu (10). 9 And 10 reversibly dissoc. one PR3 ligand, yielding diamagnetic [Fe(PR3)(tpS4)] fragments. These findings explain the decisive and hitherto inexplicable influence of PPr3 and PBu3 upon the stabilization of N2H2 in the diazene complexes [μ-N2H2Fe(PR3)(tpS4)2] with R = Pr, Bu. Treatment of (1) or (3) with NO or NO+ yielded [Fe(NO)2(tpS4)] (12). The mol. structures of 3, 4, 7 and 8 were detd. by x-ray structure anal. Spectroscopic and structural results indicate that the differences in reactivity between [Fe(L1)(L2)(tpS4)] and homologous [Fe(L1)(L2)(S4)] complexes can be traced back to subtle electronic and structural effects. [on SciFinder(R)]

syn-Tri-mu-chlorido-bis[(R,R)/(S,S)-2,2'-bis(diphenylphosphino)-1,1'-biphenyl]hydridoiridium(III) tetrafluoridoborate dichloromethane disolvate. - Dahlenburg, Lutz; Heinemann, Frank Wilhelm; Kramer, Dagmar; Menzel, Ralf (Acta crystallographica. Section C, Crystal structure communications, 2008)
In the structure of the title compound, [Ir(2)Cl(3)H(2)(C(36)H(28)P(2))(2)]BF(4) x 2 CH(2)Cl(2), the bimetallic cation features a confacial bioctahedral structure that is held together by three bridging chloride ions and is very close to C(2) symmetric. The hydrides are in a syn orientation (trans to the same halide bridge), and the chelating bis(phosphine) atropisomers display a racemic (R,R)/(S,S) configuration. Because of the high trans-bond-weakening influence of the hydride ligands, the Ir-Cl bonds trans to Ir-H [2.5262 (7) and 2.5365 (7) A] are significantly longer than those opposite the Ir-P linkages [2.4287 (7)-2.4672 (8) A]. The Ir-P distances vary between 2.2464 (9) and 2.2565 (8) A. This study illustrates the usefulness of sterically demanding biaryl-based P(2) ligands in the synthesis of halide-bridged Ir(2) complexes, which are valuable precursors of versatile catalysts for homogeneous C=O hydrogenation.

Systematic counterion tuning of the solid-state structure of [Pt(thiourea)(4)](2+) - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2007)
Four different limiting molecular conformations are possible for the homoleptic square-planar complex tetrakis (thiourea) platinum(II) depending on the up-down orientation of the four thiourea (TU) ligands with respect to the PtS4 plane. The realization of all four possible conformers can be achieved by a systematic variation of the counter anion making use of their individual hydrogen bonding ability. In total, the molecular and crystal structures of seven tetrakis (thiourea) platinum(II) complexes were determined by X-ray diffraction. These are: [Pt(TU)(4)]Cl-2, [Pt(TU)(4)]I-2, [Pt(TU)(4)](CF3SO3)(2), [Pt(TU)(4)](BPh4)(2), [Pt(TU)(4)](CIO4)(2), [Pt(TU)(4)]SiF(6)(.)0.25H(2)O and [Pt(TU)(4)]S2O6. In all cases thiourea is coordinated by the sulfur atom and the two amino groups are not involved in the complex formation. The four independent Pt-S distances do not differ significantly from each other with an average value of 2.324(3) angstrom. The coordination geometry around the platinum center is distorted square-planar. The orientation of the four TU groups in [Pt(TU)(4)](2+) depends on the molecular packing forces and hydrogen bonding ability of the counter aO0 and S) are observed. (c) Wiley-VCH Verlag GmbH & Co. KGaA.
Keywords: counter ion; conformers; crystal engineering

Systematic increase of electrocatalytic turnover at nanoporous platinum surfaces prepared by atomic layer deposition - Assaud, Loic; Schumacher, Johannes; Tafel, Alexander; Bochmann, Sebastian; Christiansen, Silke; Bachmann, Julien (Journal of Materials Chemistry A, 2015)
We establish a procedure for the fabrication of electrocatalytically active, nanoporous surfaces coated with Pt and exhibiting a high geometric area. Firstly, the mechanism of the surface reactions between platinum(II) acetylacetonate and ozone is investigated by piezoelectric microbalance measurements. The data reveal that ozone oxidizes the metallic Pt surface to an extent which can exceed one monolayer depending on the reaction conditions. Proper reaction parameters yield a self-limited growth in atomic layer deposition (ALD) mode. Secondly, the ALD procedure is applied to porous anodic oxide substrates. The morphology and the crystal structure of the deposits are characterized. The ALD coating results in a continuous layer of Pt nanocrystallites along deep pore walls (aspect ratio 70). Thirdly, the Pt/TiO2 surfaces are shown to be electrochemically active in both acidic and alkaline media, in a way that qualitatively conforms to literature precedents based on Pt. Finally, we apply the anodization and ALD procedure to commercial Ti felts and demonstrate systematically how the electrochemical current density is increased by the large specific surface area and by the presence of the catalyst. Thereby, the catalyst loading, as well as its efficient utilization, can be optimized accurately. The preparative approach demonstrated here can be generalized and applied to the various electrocatalytic reactions of energy conversion device

Systematic tuning of segmented magnetic nanowires into three-dimensional arrays of ‘bits’ - Bochmann, Sebastian; Fernández-Pacheco, Amalio; Mackovic, Mirza; Neff, Andreas; Siefermann, Katrin Rita; Spiecker, Erdmann; Cowburn, Russell P.; Bachmann, Julien (RSC Advances, 2017)
A method is presented for the preparation of a three-dimensional magnetic data storage material system. The major ingredients are an inert nanoporous matrix prepared by anodization and galvanic plating of magnetic and non-magnetic metals in wire shape inside the cylindrical pores. The individual nanomagnets consist of a nickel–cobalt alloy, the composition of which is tuned systematically by adjusting the electrolytic bath composition at one optimal applied potential. The lowest magnetocrystalline anisotropy is obtained at the composition Ni60Co40, as quantified by superconducting quantum interference device magnetometry. Wires of this composition experience a pinning-free propagation of magnetic domain walls, as determined by single-wire magneto-optical Kerr effect magnetometry. Adding copper into the electrolyte allows one to generate segments of Ni60Co40 separated by non-magnetic copper. The segment structure is apparent in individual nanowires imaged by scanning electron microscopy, UV-photoelectron emission microscopy, and transmission electron microscopy. The single-domain structure of the wire segments is evidenced by magnetic force microscopy.

Tailored nanoparticles by wet chemical particle technology: From lab to pilot scale - Flegler, Andreas; Wintzheimer, Susanne; Schneider, Michael; Gellermann, Carsten; Mandel, Karl (Handbook of Nanomaterials for Industrial Applications, 2018)
In this chapter the merits of employing nanoparticles synthesized in dispersion via bottom-up wet chemistry in advanced materials are pointed out. Yet, the reality shows that there is a lack of nanoparticles made this way in “real-life” applications. Potential reasons for that are briefly outlined, pointing towards the challenges of upscaling of wet chemical nanoparticle syntheses. In four sample cases of nanoparticle synthesis upscaling from milligram to multigram and kilogram scale, the encounter of these challenges is described and examples are given as to how they could be overcome. In the view of the authors, these examples demonstrate that there is exciting science and engineering behind wet chemical nanoparticle synthesis upscaling. Not only with respect to achieving “real-life” applications, but also with respect to new scientific discoveries, this field of colloidal engineering is worth to be pursued a lot more in future.
CRIS-Team Scopus Importer:2020-04-02
Keywords: Bottom-up; Colloid chemistry; Colloidal engineering; Large scale nanoparticle synthesis; Nano chemistry; Nanomaterials; Nanoparticles; Pilot scale; Upscaling

Tailoring magnetic supraparticles for object identification by magnetic particle spectroscopy - Müssig, Stephan; Fidler, F.; Haddad, D.; Hiller, K. H.; Wintzheimer, Susanne; Mandel, Karl (International Journal of Magnetic Particle Imaging, 2020)
Marking and identification of materials is becoming increasingly important due to complex global resource and supply chains. In this work, a miniaturized magnetic marking technology based on so-called supraparticles is presented. The hierarchical buildup of these microparticles, which are assembled from nanoparticles, allows to precisely tailor their structure. Superparamagnetic iron oxide nanoparticles as building blocks are used in this work. By surface modification and mixing them with silica nanoparticles, respectively, the supraparticle structure is varied. It is demonstrated that these structural modifications are readily detected by magnetic particle spectroscopy (MPS). Thereby, various distinguishable magnetic signals are feasible, which are even detected after incorporation into dark plastic. The presented magnetic marking technology thus proves its potential as an alternative marking technology to optical labels.
CRIS-Team Scopus Importer:2020-11-20

Tale of Three Molecular Nitrides: Mononuclear Vanadium (V) and (IV) Nitrides As Well As a Mixed-Valence Trivanadium Nitride Having a V3N4Double-Diamond Core - G. Jafari, Mehrafshan; Fehn, Dominik; Reinholdt, Anders; Hernández-Prieto, Cristina; Patel, Prajay; Gau, Michael R.; Carroll, Patrick J.; Krzystek, J.; Liu, Cong; Ozarowski, Andrew; Telser, Joshua; Delferro, Massimiliano; et al. (Journal of the American Chemical Society, 2022)
Transmetallation of [VCl3(THF)3] and [TlTptBu,Me] afforded [(TptBu,Me)VCl2] (1, TptBu,Me = hydro-tris(3-tert-butyl-5-methylpyrazol-1-yl)borate), which was reduced with KC8 to form a C3v symmetric VII complex, [(TptBu,Me)VCl] (2). Complex 1 has a high-spin (S = 1) ground state and displays rhombic high-frequency and -field electron paramagnetic resonance (HFEPR) spectra, while complex 2 has an S = 3/2 4A2 ground state observable by conventional EPR spectroscopy. Complex 1 reacts with NaN3 to form the VV nitride-azide complex [(TptBu,Me)VN(N3)] (3). A likely VIII azide intermediate en route to 3, [(TptBu,Me)VCl(N3)] (4), was isolated by reacting 1 with N3SiMe3. Complex 4 is thermally stable but reacts with NaN3 to form 3, implying a bis-azide intermediate, [(TptBu,Me)V(N3)2] (A), leading to 3. Reduction of 3 with KC8 furnishes a trinuclear and mixed-valent nitride, [(TptBu,Me)V2(μ4-VN4)] (5), conforming to a Robin-Day class I description. Complex 5 features a central vanadium ion supported only by bridging nitride ligands. Contrary to 1, complex 2 reacts with NaN3 to produce an azide-bridged dimer, [(TptBu,Me)V2(1,3-μ2-N3)2] (6), with two antiferromagnetically coupled high-spin VII ions. Complex 5 could be independently produced along with [(κ2-TptBu,Me)2V] upon photolysis of 6 in arene solvents. The putative VIVN intermediate, [(TptBu,Me)VN] (B), was intercepted by photolyzing 6 in a coordinating solvent, such as tetrahydrofuran (THF), yielding [(TptBu,Me)VN(THF)] (B-THF). In arene solvents, B-THF expels THF to afford 5 and [(κ2-TptBu,Me)2V]. A more stable adduct (B-OPPh3) was prepared by reacting B-THF with OPPh3. These adducts of B are the first neutral and mononuclear VIV nitride complexes to be isolated.
CRIS-Team Scopus Importer:2022-06-24

Teaming up main group metals with metallic iron to boost hydrogenation catalysis - Färber, Christian; Stegner, Philipp; Zenneck, Ulrich; Knüpfer, Christian; Bendt, Georg; Schulz, Stephan; Harder, Sjoerd (Nature Communications, 2022)
Hydrogenation of unsaturated bonds is a key step in both the fine and petrochemical industries. Homogeneous and heterogeneous catalysts are historically based on noble group 9 and 10 metals. Increasing awareness of sustainability drives the replacement of costly, and often harmful, precious metals by abundant 3d-metals or even main group metals. Although not as efficient as noble transition metals, metallic barium was recently found to be a versatile hydrogenation catalyst. Here we show that addition of finely divided Fe-0, which itself is a poor hydrogenation catalyst, boosts activities of Ba-0 by several orders of magnitude, enabling rapid hydrogenation of alkynes, imines, challenging multi-substituted alkenes and non-activated arenes. Metallic Fe-0 also boosts the activity of soluble early main group metal hydride catalysts, or precursors thereto. This synergy originates from cooperativity between a homogeneous, highly reactive, polar main group metal hydride complex and a heterogeneous Fe-0 surface that is responsible for substrate activation.
CRIS-Team WoS Importer:2022-07-01

Template and pH-mediated synthesis of tetrahedral indium complexes [Cs<In4(L)4 - Saalfrank, Rolf; Maid, Harald; Scheurer, Andreas; Heinemann, Frank Wilhelm; Puchta, Ralph; Bauer, Walter; Stern, Daniel; Stalke, Dietmar (Angewandte Chemie-International Edition)

Tetra- and triphosphane pyridine podands and their cobalt(II) and nickel(II) complexes - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2006)
The reaction of the 2,6 -diethylpyridine-derived tetraphosphane ligand C5H3N[CMe(CH2PMe2)(2)](2) (1(Me)) with nickel(II) or cobalt(II) perchlorate or tetrafluorob orate in methanol produces complexes of approximate square-pyramidal geometry (NP4 coordination). The nickel complexes are diamagnetic, with NMR spectral features ((31)p) that reflect a tetrahedral distortion of diametrically opposite phosphorus donors; this is also found in the solid state. In terms of bond lengths and angles, all complexes differ significantly from their analogues containing the phenyl- substituted ligand C5H3N[CMe(CH2PPh2)(2)](2). The ligand 1(Me) is readily and completely oxidised to the corresponding tetrakis(phosphane oxide) upon reaction with NO. Slow oxidation of the cobalt(II) tetrafluoroborate complex of 1(Me) with aerobic oxygen in acetonitrile produces a trinuclear cobalt complex containing two equivalents of partially oxidised ligand (C-2-symmetrical; donor set: [PMe2](2)[P(O)Me-2](2)). Four phosphane oxide oxygen atoms coordinate the central cobalt(II) ion in tetrahedral fashion, whereas the lateral cobalt(II) ions are in a square-pyramidal environment provided by two PMe2 donors and three acetonitrile ligands in each case. The reaction of the cobalt(II) perchlorate complex of 1(Me) with carbon monoxide gives an octahedral, 19-valence-electron dicarbonyl complex in which one of the dimethylphosphanyl groups is uncoordinated. A structural relative of 1(Me)., C5H3N[CMe(CH2PMe2)(2)][CMe2(CH2PMe2)] (2), which contains one fewer dimethylphosphanyl donor, can be prepared in a straightforward manner from 2-ethyl-6-isopropylpyridine in a four-stage process. In a series of mononuclear nickel(II) complexes, 2 employs only its three phosphane donors which, together with a monodentate ligand (acetonitrile, acetamide, or bromide), provide a tetragonal coordination environment for the metal ion which is intermediate between square planar and tetrahedral. The acetamide complex is generated from the acetonitrile complex by slow hydrolysis of the coordinated ligand. Full spectroscopic details for the complexes, as well as X-ray structure analyses, are reported.
Keywords: cobalt; nickel; N; P ligands

Tetraanionic N2O2-coordinating ligands as potential building blocks for supramolecular magnetic networks. - Milek, Magdalena; Witt, Alexander; Streb, Carsten; Heinemann, Frank Wilhelm; Khusniyarov, Marat (Dalton Transactions, 2013)
A bisoxamate ligand containing three different types of coordination sites was designed and synthesized. The developed synthetic strategy was adopted to prepare a related 1,2-bis(2-hydroxybenzamido)benzene-derived ligand. Nickel(II) complexes of both the novel ligands were obtained and characterized by X-ray crystallography, NMR, electronic absorption spectroscopy, and theoretical calculations.

Tetranuclear Nickel and Cobalt Complexes with an Incomplete Double-Cubane Structure – Homo- and Heterometallic Complexes and Their 1D Coordination Polymers - Nakajima, Takayuki; Seto, Keiko; Scheurer, Andreas; Kure, Bunsho; Kajiwara, Takashi; Tanase, Tomoaki; Mikuriya, Masahiro; Sakiyama, Hiroshi (European Journal of Inorganic Chemistry, 2014)
The reactions of M(OAc)2·4H2O (M = Ni, Co) with three unsymmetrical amine-diol ligands RN(CH2CH2OH)(CH2CH2CH2OH) (H2Ln: n = 1, R = benzyl; n = 2, R = 4-methylbenzyl; n = 3, R = 2-naphthalenylmethyl) in the presence of NEt3 or pyridine in MeOH or BnOH gave the tetranuclear complexes [M4(HLn)2(OAc)6(MeOH)2] M = Ni, n = 1 (1a), 2 (1b), 3 (1c); M = Co, n = 1 (4a), 2 (4b), 3 (4c) and [M4(HLn)2(OAc)6(BnOH)2] M = Ni, n = 1 (2a), 2 (2b), 3 (2c); M = Co, n = 1 (5a), 2 (5b), 3 (5c). When p-xylene-α,α′-diol was used instead of monoalcohols, the tetranuclear M4O6 units were linked by p-xylene-α,α′-diol to form the 1D coordination polymers [M4(HLn)2(OAc)6(p-HOCH2C6H4CH2OH)]m M = Ni, n = 1 (3a), 2 (3b); M = Co, n = 1 (6a), 2 (6b). The structures of 1–6 were determined by X-ray crystallography and consist of centrosymmetrical tetranuclear M4O6 face-shared defective double-cubane cores supported by two monodeprotonated (HLn)– ligands. The mixed-metal tetranuclear complexes [Ni2.2Co1.8(HL1)2(OAc)6(MeOH)2] (7) and [Mn1.7Ni2.3(HL1)2(OAc)5(OMe)2] (8) were also synthesized by using equimolar amounts of Ni2+ and M2+ (M = Co, Mn) ions. X-ray crystallographic and fluorescent analyses revealed that 7 is isomorphous with 1a and 4a and contains nonstoichiometric amounts of disordered Ni2+ and Co2+ ions in an average ratio of 2.2:1.8 with different occupancies for the two crystallographically independent metal centers. In contrast, 8 consists of a C2-symmetrical face-shared defective double-cubane MII3MnIIIO6 core with a Ni/Mn ratio of 2.3:1.7; the amounts of Ni2+ and Mn2+ ions vary depending on the metal sites, and one of the C2 axial positions is exclusively occupied by Mn3+ ions. Detailed magnetostructural analyses on the nickel (1a, 2a, 3a) and cobalt (4a) complexes with appropriate spin-Hamiltonian models showed that both ferro- and antiferromagnetic spin exchange interactions were involved within the tetranuclear units, and their extent depends on the combination of the metal ions and the ligand systems in a delicate fashion.
Keywords: Tetranuclear complexes; Coordination polymers; Nickel; Cobalt; N; O ligands

Tetrapodal Pentadentate Ligands with NS_4_ and NP_4_ Donor Sets: An Elusive Tetrathiol, and a Sterically Encumbered Tetraphosphane - Grohmann, Andreas; Zimmermann, Christopher; Bauer, Walter; Heinemann, Frank Wilhelm (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2002)
UnivIS-Import:2017-03-24:Pub.2002.forsch.sonder.sfb583.tetrap

The activation of tertiary carboxamides in metal complexes: An experimental and theoretical study on the methanolysis of acylated bispicolylamine copper(II) complexes - Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry, 2004)

The biology and chemistry of high-valent iron-oxo and iron-nitrido complexes - Hohenberger, Johannes; Ray, Kallol; Meyer, Karsten (Nature Communications, 2012)
Selective functionalization of unactivated C-H bonds and ammonia production are extremely important industrial processes. A range of metalloenyzmes achieve these challenging tasks in biology by activating dioxygen and dinitrogen using cheap and abundant transition metals, such as iron, copper and manganese. High-valent iron-oxo and -nitrido complexes act as active intermediates in many of these processes. The generation of well-described model compounds can provide vital insights into the mechanism of such enzymatic reactions. Advances in the chemistry of model high-valent iron-oxo and -nitrido systems can be related to our understanding of the biological systems. © 2012 Macmillan Publishers Limited. All rights reserved.

The challenge of deodorizing post-consumer polypropylene packaging: Screening of the effect of washing, color-sorting and heat exposure - Strangl, Miriam; Lok, Bianca; Breunig, Pascal; Ortner, Eva; Büttner, Andrea (Resources Conservation and Recycling, 2021)
For promoting a sustainable end-of-life-management for plastic packaging, mechanical recycling of especially post-consumer plastic packaging waste constantly gains more attention. To fulfill both industrial and consumer demands, and to increase the recycled content in new applications, high-quality recyclates are of prime importance. However, the odor contamination of post-consumer polyolefin recyclates is not only limiting their application field but is also of concern for the recycling industry and plastic converters since odor emissions during processing might affect the workers’ well-being. As the development of targeted odor reduction strategies requires detailed insights into causative odorants, the present study addresses the odor characterization of different recycled post-consumer polypropylene from the packaging sector by coupling human sensory and comprehensive instrumental analyses. Thereby, the impact of different washing procedures and color sorting were evaluated in terms of their odor reduction potential. In contrast to color sorting, implementation of a hot water washing step led to a noteworthy odor reduction since intensity ratings declined from 7.4 to 4.0, albeit the odor intensity was still not comparable to the low odor level of investigated virgin polypropylene (intensity rating of 2.1). Moreover, a screening on heat-induced emissions of odorous contaminants inspired by a standard extrusion process was performed, revealing a greater emission of odorants in terms of both number and perceived intensities with increasing temperature.
CRIS-Team Scopus Importer:2020-09-11
Keywords: Contaminants; Odor; Olfactometry; Plastic; Polyolefin; Recycling

The classic "brown-ring" reaction in a new medium: kinetics, mechanism, and spectroscopy of the reversible binding of nitric oxide to iron(II) in an ionic liquid. - Begel, Svetlana; Heinemann, Frank Wilhelm; Stopa, Grzegorz; Stochel, Grazyna; van Eldik, Rudi (Inorganic Chemistry, 2011)
To elucidate the applicability and properties of ionic liquids (ILs) to serve as chemical reaction media for the activation of small molecules by transition-metal complexes, detailed kinetic and mechanistic studies were performed on the reversible binding of NO to FeCl(2) dissolved in the IL 1-ethyl-3-methylimidazolium dicyanamide ([emim][dca]) as a solvent. We report, for the first time, the application of laser flash photolysis at ambient and high pressure to study the kinetics of this reaction in an IL. The kinetic data and activation parameters for the "on" and "off" reactions suggest that both processes follow a limiting dissociative (D) ligand substitution mechanism, in contrast to that reported for the same reaction in aqueous solution, where this well-known "brown-ring" reaction follows an interchange dissociative (I(d)) ligand substitution mechanism. The observed difference apparently arises from the participation of the IL anion as a N-donor ligand, as evidenced by the formation of polymeric [Fe(dca)(3)Cl](x)[emim](2x) chains in the solid state and verified by X-ray crystallography. In addition, infrared (IR), Mössbauer, and EPR spectra were recorded for the monomeric reaction product [Fe(dca)(5)NO](3-) formed in the IL, and the parameters closely resemble those of the FeNO(7) unit in other well-characterized nitrosyl complexes. It is concluded that its electronic structure is best described by the presence of a high-spin Fe(III) (S = 5/2) center antiferromagnetically coupled to NO(-) (S = 1), yielding the observed spin quartet ground state (S(t) = 3/2).

The crown ether influence on ligand exchange reactions of Na2PtCl6 with glycine and D-(+)-alanine; synthesis and characterization of of platinum(IV) amino acid complexes - Steinborn, Dirk; Junicke, H.; Heinemann, Frank Wilhelm (Inorganica Chimica Acta, 1997)

The deposition of metallopeptide-based coordination polymers on graphite substrates: effects of side-chain functional groups and local surface structure. - Heinemann, Frank Wilhelm; et al. (Angewandte Chemie International Edition, 2005)

The electronic ground state of [Fe(CO)3(NO)]-: A spectroscopic and theoretical study - Klein, Johannes E. M. N.; Miehlich, Burkhard; Holzwarth, Michael S.; Bauer, Matthias; Milek, Magdalena; Khusniyarov, Marat; Knizia, Gerald; Werner, Hans-Joachim; Plietker, Bernd (Angewandte Chemie International Edition, 2014)
Keywords: electronic structure; Enemark-Feltham notation; spectroscopy; ferrates; iron catalysis

The [Fe(III)[Fe(III)(L1)2]3] star-type single-molecule magnet. - Heinemann, Frank Wilhelm; et al. (Dalton Transactions, 2006)
Star-shaped complex [Fe(III)[Fe(III)(L1)2]3] (3) was synthesized starting from N-methyldiethanolamine H2L1 (1) and ferric chloride in the presence of sodium hydride. For 3, two different high-spin iron(III) ion sites were confirmed by Mössbauer spectroscopy at 77 K. Single-crystal X-ray structure determination revealed that 3 crystallizes with four molecules of chloroform, but, with only three molecules of dichloromethane. The unit cell of 3.4CHCl3 contains the enantiomers (delta)-[(S,S)(R,R)(R,R)] and (lambda)-[(R,R)(S,S)(S,S)], whereas in case of 3.3CH2Cl2 four independent molecules, forming pairs of the enantiomers [lambda-(R,R)(R,R)(R,R)]-3 and [lambda-(S,S)(S,S)(S,S)]-3, were observed in the unit cell. According to SQUID measurements, the antiferromagnetic intramolecular coupling of the iron(III) ions in 3 results in a S = 10/2 ground state multiplet. The anisotropy is of the easy-axis type. EPR measurements enabled an accurate determination of the ligand-field splitting parameters. The ferric star 3 is a single-molecule magnet (SMM) and shows hysteretic magnetization characteristics below a blocking temperature of about 1.2 K. However, weak intermolecular couplings, mediated in a chainlike fashion via solvent molecules, have a strong influence on the magnetic properties. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) were used to determine the structural and electronic properties of star-type tetranuclear iron(III) complex 3. The molecules were deposited onto highly ordered pyrolytic graphite (HOPG). Small, regular molecule clusters, two-dimensional monolayers as well as separated single molecules were observed. In our STS measurements we found a rather large contrast at the expected locations of the metal centers of the molecules. This direct addressing of the metal centers was confirmed by DFT calculations.

The First Lanthanide Complexes with a Redox-Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*2(RN=)2S], Ln=Sm, Eu, Yb; R=SiMe3 - Klementyeva, Svetlana V.; Gritsan, Nina P.; Khusniyarov, Marat; Witt, Alexander; Dmitriev, Alexey A.; Suturina, Elizaveta A.; Hill, Nathan D. D.; Roemmele, Tracey L.; Gamer, Michael T.; Boere, Rene T.; Roesky, Peter W.; Zibarev, Andrey V.; et al. (Chemistry - A European Journal, 2017)
Keywords: sulfur diimide; quantum chemical calculations; radicals; lanthanides; magnetism

The influence of storage conditions on flavour changes in human milk. - Spitzer, Johanna; Doucette, Suzanne C.; et al. (Food Quality and Preference, 2010)
The effects of freeze-storage on human milk have been investigated with regard to sensory changes and modifications in the molecular composition of constituent odour-active volatiles. Sensory evaluation showed that fishy-metallic odour attributes are generated during storage, as are rancid-sweaty odour notes, which were described by panellists to be highly unpleasant. To monitor the dynamics of off-odour development in human milk, sensory evaluation in both orthonasal and retronasal mode was performed at defined time intervals of storage, with parallel evaluation of human milk samples that had been heated prior to freeze-storage. Heating was found to induce slight flavour changes, with generation of a predominantly egg-white-like note, but with no further generation of off-odour formation upon subsequent storage. This suggests that the formation of the off-odour in non-heated milk resulted from metabolic processes in the milk, although may also be due to the specific composition of human milk. In comparison, similar off-odour development was not observed in bovine milk. Molecular identification of the off-odour substances, most specifically free fatty acids and oxidation derivatives of polyunsaturated fatty acids, indicated both lipolytic and peroxidative processes of components of the native human milk. Finally, these results indicate that human milk is obviously a highly sensitive food material, specifically with regard to its characteristic fatty acid composition.<br

The influence of terpyridine as ð-acceptor ligand on the kinetics and mechanism of the reaction of NO with ruthenium(III) complexes - van Eldik, Rudi; Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry, 2004)
The kinetics of the unusually fast reaction of cis- and trans-[Ru(terpy)(NH3)2Cl]2+ (with respect to NH3; terpy=2,2':6',2"-terpyridine) with NO was studied in acidic aqueous solution. The multistep reaction pathway observed for both isomers includes a rapid and reversible formation of an intermediate Ru(III)-NO complex in the first reaction step, for which the rate and activation parameters are in good agreement with an associative substitution behavior of the Ru(III) center (cis isomer, k1=618 +/- 2 M(-1) s(-1), DeltaH(++) = 38 +/- 3 kJ mol(-1), DeltaS(++) = -63 +/- 8 J K(-1) mol(-1), DeltaV(++) = -17.5 +/- 0.8 cm3 mol(-1); k -1 = 0.097 +/- 0.001 s(-1), DeltaH(++) = 27 +/- 8 kJ mol(-1), DeltaS(++) = -173 +/- 28 J K(-1) mol(-1), DeltaV(++) = -17.6 +/- 0.5 cm3 mol(-1); trans isomer, k1 = 1637 +/- 11 M(-1) s(-1), DeltaH(++) = 34 +/- 3 kJ mol(-1), DeltaS(++) = -69 +/-11 J K(-1) mol(-1), DeltaV(++) = -20 +/- 2 cm3 mol(-1); k(-1)=0.47 +/- 0.08 s(-1), DeltaH(++)=39 +/- 5 kJ mol(-1), DeltaS(++) = -121 +/-18 J K(-1) mol(-1), DeltaV(++) = -18.5 +/- 0.4 cm3 mol(-1) at 25 degrees C). The subsequent electron transfer step to form Ru(II)-NO+ occurs spontaneously for the trans isomer, followed by a slow nitrosyl to nitrite conversion, whereas for the cis isomer the reduction of the Ru(III) center is induced by the coordination of an additional NO molecule (cis isomer, k2=51.3 +/- 0.3 M(-1) s(-1), DeltaH(++) = 46 +/- 2 kJ mol(-1), DeltaS(++) = -69 +/- 5 J K(-1) mol(-1), DeltaV(++) = -22.6 +/- 0.2 cm3 mol(-1) at 45 degrees C). The final reaction step involves a slow aquation process for both isomers, which is interpreted in terms of a dissociative substitution mechanism (cis isomer, DeltaV(++) = +23.5 +/- 1.2 cm3 mol(-1); trans isomer, DeltaV(++) = +20.9 +/- 0.4 cm3 mol(-1) at 55 degrees C) that produces two different reaction products, viz. [Ru(terpy)(NH3)(H2O)NO]3+ (product of the cis isomer) and trans-[Ru(terpy)(NH3)2(H2O)]2+. The pi-acceptor properties of the tridentate N-donor chelate (terpy) predominantly control the overall reaction pattern.
UnivIS-Import:2015-03-09:Pub.2004.nat.dchph.laoc1.theinf

The influence of the bridgehead in Saalfrank-type cryptands: prediction of ion selectivity by quantum chemical calculations XII - Balović, Jelena; Ćoćić, Dušan; Puchta, Ralph; Scheurer, Andreas; van Eldik, Rudi (Journal of Coordination Chemistry, 2020)
We examined the cation selectivity of the Saalfrank-type 2-metallocryptands [Ga2R3] and [Fe2R3] (R: 1,1'-(pyridine-2,6-diyl)bis(2-(1H-tetrazol-5-yl)ethan-1-one)) with alkaline and earth alkaline metal ions by means of DFT calculations (B3LYP/LANL2DZp) to obtain a better insight into the influence of the bridge head metal ions responsible for the cryptands ion selectivity. Based on our DFT calculations, notably the application of model equations and geometric features regarding the flexibility of the 2-metallocryptands, we identified K+, Sr2+ and Ba2+ as the best fitting ions. While [Fe2R3] has a cavity a bit larger than [Ga2R3], it prefers the Ba2+ cation, whereas [Ga2R3] selects the smaller Sr2+ cation. The good flexibility of the investigated hosts is provided by the oxygen-donor moieties of the 2-metallocryptands.
CRIS-Team Scopus Importer:2020-07-24
Keywords: cryptand; DFT-study; Selective ion complexation

The Influence of β-diiminato Ligands on As4 Activation by Cobalt Complexes - Spitzer, Fabian; Balazs, Gabor; Grassl, Christian; Keilwerth, Martin; Meyer, Karsten; Scheer, Manfred (Angewandte Chemie International Edition, 2018)
In a systematic study of the activation of As4, three [LCo(tol)] (L=β-diiminato) complexes have revealed different steric and electronic influences. 2,6-Diisopropylphenyl (Dipp) and 2,6-dimethylphenyl (dmp) flanking groups were used, one of the ligands with H backbone substituents (β-dialdiminate L0) and two with Me substituents (β-diketiminates L3 and L1). In the reaction with As4, different dinuclear products [(LCo)2As4] (LM=L0 (1), L1 (2), L3 (3)) were isolated, with all showing differently shaped [Co2As4] cores in the solid state: octahedral in 1, prismatic in 2, and asterane-like in 3. Thermal treatment of 3 leads to the abstraction of one arsenic atom to yield [(L3Co)2As3] (4). All products were comprehensively characterized by single-crystal X-ray diffraction, FD-MS, and 1H NMR spectroscopy. A rational explanation for the different reactivity is also proposed and DFT calculations shed light on the nature of the highly flexible [Co2As4] cores.
CRIS-Team Scopus Importer:2020-09-14
Keywords: paramagnetic compounds; small-molecule activation; substituent effects; yellow arsenic; β-diiminato ligand

The methylcobalt(III) complex of a tetrapodal pentadentate amine ligand, 2,6-bis(1′,3′-diamino-2′-methyl-prop-2′-yl)pyridine - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 1999)
Keywords: Cobalt complexes; Polydentate amine complexes; Crystal structures

The nitrogenase catalyzed N2-dependent HD formation: a model reaction and its significance for the FeMoco function - Sellmann, Dieter; Fürsattel, Anja; Sutter, Jörg (Coordination Chemistry Reviews, 2000)
The first completely characterized model for the nitrogenase catalyzed 'N-2 dependent HD formation' from D-2 and protons is described. This key reaction of nitrogenases is most plausibly rationalized by the 'open-side' FeMoco model, which enables us to explain the severe constraints imposed on the N-2 dependent HD formation as well as the noncompetitive inhibition of N-2 fixation by CO. (C) 2000 Elsevier Science S.A. All rights reserve
Keywords: nitrogen fixation; hydrogen; iron sulfur complexes; structure-function

Thermochemical and Structural Studies of New Chiral and Achiral Long Alkyl Chain Functionalized Imidazolinium Ionic Liquids - Seidl, Vera; Sternberg, Michelle; Heinemann, Frank Wilhelm; Schmiele, Martin; Unruh, Tobias; Wasserscheid, Peter; Meyer, Karsten (Crystal Growth and Design, 2021)
Adding to the versatile class of ionic liquids (ILs), an entirely new series of imidazolinium-based ionic liquids is reported herein, offering chirality and important thermal characteristics, such as polymorphism, glass transition, and plastic crystalline behavior. An efficient and general procedure for the preparation of long N,N′-alkyl chain-substituted compounds with either saturated (s) or chiral (c) cyclohexyl (cyC6)-substituted imidazolium (Im) backbones, namely, [C12C12RsIm][A] (A = Br-, [BF4]-, [ClO4]-, [PF6]- R = H, Me, iPr) and [C12C12cIm-cyC6][A] (A = Br-, I-, [I3]-, [BF4]-, [ClO4]-, [PF6]-, [SbF6]-, [BPh4]-), was developed, and the novel compounds were studied by thermochemical methods (DSC, TGA), X-ray diffraction in the small angle regime (SAXS), single-crystal X-ray diffraction (SC-XRD), and specific rotation analysis.
CRIS-Team Scopus Importer:2021-10-29

The role of uranium-arene bonding in H2O reduction catalysis - Halter, Dominik; Heinemann, Frank Wilhelm; Maron, Laurent; Meyer, Karsten (Nature Chemistry, 2018)
The reactivity of uranium compounds towards small molecules typically occurs through stoichiometric rather than catalytic processes. Examples of uranium catalysts reacting with water are particularly scarce, because stable uranyl groups form that preclude the recovery of the uranium compound. Recently, however, an arene-anchored, electron-rich uranium complex has been shown to facilitate the electrocatalytic formation of H2 from H2O. Here, we present the precise role of uranium–arene δ bonding in intermediates of the catalytic cycle, as well as details of the atypical two-electron oxidative addition of H2O to the trivalent uranium catalyst. Both aspects were explored by synthesizing mid- and high-valent uranium–oxo intermediates and by performing comparative studies with a structurally related complex that cannot engage in δ bonding. The redox activity of the arene anchor and a covalent δ-bonding interaction with the uranium ion during H2 formation were supported by density functional theory analysis. Detailed insight into this catalytic system may inspire the design of ligands for new uranium catalyst

The Significant Influence of the pH Value on Citrate Coordination upon Modification of Superparamagnetic Iron Oxide Nanoparticles - Granath, Tim; Mandel, Karl; Loebmann, Peer (Particle & Particle Systems Characterization, 2022)
Although citrates are commonly used to modify nanoparticles, attention is rarely paid to how the modification parameters affect the type of adsorption and, thus, possibly, the properties of the modified particles. The relevance of this and the significant impact it can have is demonstrated in this study by examining the effect of pH upon the modification of superparamagnetic iron oxide nanoparticles (SPIONs) with citrate, using a citrate concentration that yields a high molecular surface density but induces almost no coordination pressure. Relying first on a number of classical surfaces analyzing methods, no clear pH-dependent differences can be identified. Finally, the consideration of the thermally induced redox behavior gives a decisive clue to unravel the "citric acid mystery" and to put together the, until then, weak hints into an overall picture. This shows that the citrate carboxyl groups are linked to the oxidic surface pH dependently via hydrogen bonds to hydroxide groups or coordinatively to iron ions and, besides, also interact, to a certain extent, with ammonia that is used for pH adjustment. With these findings, it is finally possible to explain the observed differences when the citrate-modified SPIONs are coated with silica (SiO2) or redispersed after spray-drying.
CRIS-Team WoS Importer:2022-02-11

The synthesis and characterization of an iron(VII) nitrido complex - Keilwerth, Martin; Mao, Weiqing; Malischewski, Moritz; Jannuzzi, Sergio A.V.; Breitwieser, Kevin; Heinemann, Frank Wilhelm; Scheurer, Andreas; DeBeer, Serena; Munz, Dominik; Bill, Eckhard; Meyer, Karsten (Nature Chemistry, 2024)
Complexes of iron in high oxidation states are captivating research subjects due to their pivotal role as active intermediates in numerous catalytic processes. Structural and spectroscopic studies of well-defined model complexes often provide evidence of these intermediates. In addition to the fundamental molecular and electronic structure insights gained by these complexes, their reactivity also affects our understanding of catalytic reaction mechanisms for small molecule and bond-activation chemistry. Here, we report the synthesis, structural and spectroscopic characterization of a stable, octahedral Fe(VI) nitrido complex and an authenticated, unique Fe(VII) species, prepared by one-electron oxidation. The super-oxidized Fe(VII) nitride rearranges to an Fe(V) imide through an intramolecular amination mechanism and ligand exchange, which is characterized spectroscopically and computationally. This enables combined reactivity and stability studies on a single molecular system of a rare high-valent complex redox pair. Quantum chemical calculations complement the spectroscopic parameters and provide evidence for a diamagnetic (S = 0) d 2 Fe(VI) and a genuine S = 1/2, d 1 Fe(VII) configuration of these super-oxidized nitrido complexes. [Figure not available: see fulltext.]
CRIS-Team Scopus Importer:2024-02-09

The zinc aqua complex of a tetrapodal pentaamine ligand and its reactivity towards carbon dioxide - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2004)
Keywords: Carbon Dioxide Fixation; Aqua Complex; Zinc; Tetrapodal Pentadentate Ligand

Thin film formation of wet chemically deposited NiOx and parasitic oxides at NiOx/Si interfaces during high-temperature annealing of selective contacts in perovskite/Si tandem solar cells - Lange, Stefan; Fett, Bastian; Hähnel, Angelika; Müller, Alexander; Herbig, Bettina; Naumann, Volker; Sextl, Gerhard; Mandel, Karl; Hagendorf, Christian (Solar Energy Materials and Solar Cells, 2022)
Wet chemically deposited NiOx is a promising hole-transport material in perovskite/Si tandem solar cells due to its high work function, chemical stability, and low cost. However, it requires subsequent annealing that may lead to the formation of SiOz at the Si interface to the bottom cell. These layers of nm thickness exhibit non-stoichiometric chemical composition and are detrimental for charge transport and passivation. In this contribution, we investigate the atomic and electronic structure as well as chemical properties of NiOx layers on Si after wet chemical deposition and annealing in air between 200 °C and 600 °C. For this purpose, photoelectron spectroscopy, X-ray diffraction, differential thermal analysis/thermogravimetric analysis coupled with Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry, and electron-energy loss spectroscopy in a scanning transmission electron microscope are applied. After deposition and annealing at 200 °C, a mixed bulk phase consisting of NiOxHy is found which transforms to pure NiOx above 300 °C. A parasitic SiOz layer is observed at the NiOx/Si interface after this process, with a thickness of 3–4 nm after annealing at 500 °C. The impact of this interfacial layer for electrical current transport will be discussed concerning optimized performance and integrability in perovskite/silicon tandems.
CRIS-Team Scopus Importer:2022-04-08
Keywords: Annealing; Interfaces; Nickel oxide; Perovskites; Selective contacts; Tandem solar cells; Transmission electron microscopy

Thio-oxalic Acid 2-Amide-1-hydrazide-2-hydrazone - Heinemann, Frank Wilhelm; Hartung, H; Dehne, Henry; Scheunemann, A. (Acta crystallographica. Section C, Crystal structure communications, 1995)

Thiooxalsäure-2-amid-1-hydrazid-2-hydrazon: eine neue zwitterionische Verbindung - Dehne, H.; Scheunemann, A.; Michalik, M.; Hartung, H; Heinemann, Frank Wilhelm; Kibbel, U. (Phosphorus Sulfur and Silicon and the Related Elements, 1994)

Threading cesium ions: metal, host, and ligand control in supramolecular coordination chemistry. - Heinemann, Frank Wilhelm; et al. (Angewandte Chemie International Edition, 2007)

TiO2 Nanotubes: Nitrogen-Ion Implantation at Low Dose Provides Noble-Metal-Free Photocatalytic H-2-Evolution Activity - Zhou, Xuemei; Häublein, Volker; Liu, Ning; Nguyen, Nhat Truong; Zolnhofer, Eva; Tsuchiya, Hiroaki; Manuela, Killian; Meyer, Karsten; Schmuki, Patrik; Frey, Lothar (Angewandte Chemie International Edition, 2016)
Low-dose nitrogen implantation induces an ion and damage profile in TiO2 nanotubes that leads to co-catalytic activity for photocatalytic H-2-evolution (without the use of any noble metal). Ion implantation with adequate parameters creates this active zone limited to the top part of the tubes. The coupling of this top layer and the underlying non-implanted part of the nanotubes additionally contributes to an efficient carrier separation and thus to a significantly enhanced H-2 generatio
Keywords: H-2 evolution; ion implantation; nitrogen; photocatalysis; TiO2 nanotubes

Titanium isopropoxide complexes containing diamine bis-thiolato based [N2S2](2-) ligands; effect of steric bulk on coordination features - Shaban, Shaban Y.; Ramadan, Abd El-Motaleb M.; Heinemann, Frank Wilhelm (Inorganic Chemistry Communications, 2012)
Two dianionic amine bis(thiolato) ligands are introduced and their reactions with titanium tetra(iso-propoxide) studied; ligand N2H2S2 - H-2 (1) having NH donor groups leads exclusively to dinuclear [Ti(N2H2S2)((OPr)-Pr-i)(2)] (2) along with an oxidation product of the ligand (3) whereas ligand N2Me2S2 - H-2 (4) having an additional N-substituent leads exclusively to a mononuclear [Ti(N2Me2S2)((OPr)-Pr-i)(2))] (5) type complex. (C) 2012 Elsevier B.V. All rights reserved.
Keywords: Titanium complexes; Structure; Bis-thiolato complexes; Amide coordination; Thiolate oxidation; Hydrolysis

Topochemical investigations of dimerizing 4-aryl-1,4-dihydropyridines by X-ray crystal structure analysis - Heinemann, Frank Wilhelm; et al. (Journal of Molecular Structure, 1999)
Keywords: X- ray crystal structure analysis; Protection; 1; 4-dihydropyridines; Topochemistry; Solid-state reaction

Topochemie dimerisierender 1,4- Dihydropyridine als Vorstufen potentieller HIV-1-Protease-Inhibitoren - Hilgeroth, Andreas; Baumeister, U.; Heinemann, Frank Wilhelm (Fachgruppentagung der Fachgruppe „Pharmazeutische Chemie“, 1997)

To Professor Rolf W. Saalfrank on the Occasion of his 70th birthday - Puchta, Ralph; Scheurer, Andreas (Zeitschrift für Naturforschung 2010, 2010)

Towards core-shell bifunctional catalyst particles for aqueous metal-air batteries: NiFe-layered double hydroxide nanoparticle coatings on gamma-MnO2 microparticles - Flegler, Andreas; Muessig, Stephan; Prieschl, Johannes; Mandel, Karl; Sextl, Gerhard (Electrochimica Acta, 2017)
Herein, we investigated the synthesis of a bifunctional catalyst particle system for aqueous metal-air batteries. To target a system which possesses both, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) capabilities, gamma-MnO2 microparticles were combined with NiFe layered double hydroxides (LDH) to a core-shell system. NiFe-LDH can be optimized in its constituency to yield a very low onset potential (at 10 mA cm (2)) for the oxygen evolution reaction of only 569 mV vs. Hg/HgO. We investigated different coating processes (in-situ precipitation coating and sonochemical assisted coating) in order to create a bifunctional system of LDH shell@gamma-MnO2 core. It was found that the overall catalytic functionality of the bifunctional system strongly depends on the coating process, as this ultimately determines the surface nature and thus the behavior in ORR and OER reactions, respectively, of this core-shell system. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords: NiFe LDH; layered double hydroxides; metal-air batteries; OER; bifunctional catalyst

Towards enantiopure macrocyclic trans-dinucleating hemilabile P-Alkene ligands: Syntheses, structures, and Chiral Pd-Complexes - Frieß, Sibylle; Herrera, Alberto Cesar; Linden, Anthony; Heinemann, Frank Wilhelm; Dorta, Romano (Journal of Organometallic Chemistry, 2019)
Dibenzazepinyl dichlorophosphine 2 reacts with (R,R)-2,3-O-isopropylidene-threitol (3) in Et2O solution to afford gram-quantities of the enantiopure macrocylic phosphoramidite (all-R)-6, which may be seen as a formal dimer of classic phosphoramidite P-alkene hybrid ligands. Complexation experiments with PdCl2 reveal highly selective formation of the trans-dinuclear complex (all-R)-11. The corresponding bulkier and rigidly trans-eclipsed 1,4-diol (S,S)-bis-hydroximethyl-9,10-dihydro-9,10-ethaneanthracene (4) does not favor macrocycle formation and exclusively leads to the new dibenzazepinyl phsophormaidite P-alkene ligand 7, which in Pd-catalyzed asymmetric allylic amination comes the well-known ‘privileged’ binol-derived P-alkene analogue 1 close in terms of enantioselection.
CRIS-Team Scopus Importer:2019-08-16
Keywords: Asymmetric allylic amination; Chiral macrocycle; Chiral P-alkene ligands; Hemilability; Phosphoramidites; trans-dinuclear palladium complex

Towards Ruthenium-Based Building Blocks for CuAAC Click Reactions: Challenges in Generating Ruthenium(II) Polypyridine Alkynes - Zabarska, Natalia; Sorsche, Dieter; Heinemann, Frank Wilhelm; Glump, Susanne; Rau, Sven (European Journal of Inorganic Chemistry, 2015)
Ag+-free complexation of alkyne-bipyridines at ruthenium(II) polypyridine centers proceeds with surprisingly low yields. The alkyne-bipyridine-substituted ruthenium(II) polypyridine complexes in this work were characterized by NMR spectroscopy, ESI spectrometry, and single-crystal X-ray structural analysis. A detailed analysis of the side products revealed an unexpected carbon-carbon alkyne bond splitting promoted by the ruthenium(II) center, leading to the formation of a CO-Ru-II species, methyl-bipyridine, and a methyl-bipyridine-substituted ruthenium(II) complex accompanying the target product. The side products were characterized using complimentary methods including X-ray crystallography. A possible mechanism is suggested based on these side products and exemplary reaction studies.
Keywords: Alkyne ligands; Carbonyl ligands; Click chemistry; Coordination modes; Ruthenium

Trans-1,2-bis(N-methylimidazol-2-yl)ethylene: Towards building blocks for 2D fabrics and MML-type 1D molecular strands - Fischer, Nina; Alam, Sahabul; Jum'H, Inshad; Stocker, Michael; Fritsch, Nico; Dremov, Viatcheslav; Heinemann, Frank Wilhelm; Burzlaff, Nicolai; Müller, Paul (Chemistry - A European Journal, 2011)
Find the thread: Copper acetate and trans-bis(N-methylimidazol-2-yl) ethylene-derived 1D coordination polymers were investigated on mica and highly oriented pyrolytic graphite (HOPG) substrates by using AFM/STM. On HOPG, single isolated strands were mapped by STM and their electronic properties were subsequently characterized by current imaging tunneling spectroscopy. On mica the material shows a tendency to form bundles of strands. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transfer Reagent for Bonding Isomers of Iron Complexes - Schmidt, Monika; Seitz, Andreas E.; Eckhardt, Maria; Balazs, Gabor; Peresypkina, Eugenia V.; Virovets, Alexander V.; Riedlberger, Felix; Bodensteiner, Michael; Zolnhofer, Eva; Meyer, Karsten; Scheer, Manfred (Journal of the American Chemical Society, 2017)
The cothermolysis of As4 and [Cp″2Zr(CO)2] (Cp″ = η5-C5H3tBu2) results in the formation of [Cp″2Zr(η1:1-As4)] (1) in high yields and the arsenic-rich complex [(Cp″2Zr)(Cp″Zr)(μ, η2:2:1-As5)] (2) as a minor product. In contrast to yellow arsenic, 1 is a light-stable, weighable and storable arsenic source for subsequent reactions. The transfer reaction of 1 with [Cp'Fe(μ-Br)]2 (Cp' = η5-C5H2tBu3) yields the unprecedented bond isomeric complexes [(Cp'Fe)2(μ, η4:4-As4)] (3a) and [(Cp'Fe)2(μ, η4:4-cyclo-As4)] (3b). In contrast, the analogous reaction with the CpBn derivative [CpBnFe(μ-Br)]2 (CpBn = η5-C5(CH2(C6H5)5) leads exclusively to the triple decker complex [(CpBnFe)2(μ, η4:4-As4)] (4) possessing the tetraarsabutadiene-type ligand analogous to 3a. To elucidate the stability of the bonding isomers 3a and 3b, DFT calculations were performed. The oxidation of 4 with AgBF4 affords [(CpBnFe)2(μ, η5:5-As5)][BF4] (5), which is a product expanded by one arsenic atom, instead of the expected complex [(CpBnFe)2(μ, η4:4-cyclo-As4)]+.
CRIS-Team Scopus Importer:2020-09-14

Transition metal complexes bearing a 2,2-bis(3,5-dimethylpyrazol-1-yl) propionate ligand: One methyl more matters - Türkoglu, Gazi; Heinemann, Frank Wilhelm; Burzlaff, Nicolai (Dalton Transactions, 2011)
The new N,N,O ligand 2,2-bis(3,5-dimethylpyrazol-1-yl)propionic acid (2,2-Hbdmpzp) (2) and its transition metal complexes [Mn(2,2-bdmpzp)(CO) ] (3), [Re(2,2-bdmpzp)(CO) ] (4), [Cu(2,2-bdmpzp) ] (5), and [Ru(2,2-bdmpzp)Cl(L)(PPh )] [L = PPh (6), N (7), CO (8a/b), SO (9a/b)] have been synthesized, characterized and compared to analogous complexes bearing a bis(3,5-dimethylpyrazol-1-yl)acetic acid. It was found that the additional methyl group has a remarkable influence on the stability and reactivity of transition metal complexes. © 2011 The Royal Society of Chemistry.

Transition metal complexes of diazenes XLI: Cobalt catalyzed addition of internal alkynes to 1,2-diaryldiazenes: Formation of 2,3-dihydrocinnolines, mono- and distilbenylazobenzenes - Heinemann, Frank Wilhelm; et al. (Journal of Organometallic Chemistry, 1998)
Keywords: Stilbenylazobenzene; Hydride complexes; Ortho-metalation; 2; 3-Dihydrocinnoline; 1; 2-Diaryldiazenes; Cobalt catalysis; Alkyne insertion

Transition metal complexes of diazenes XXXIX: Stilbenylazobenzene derivatives by cobalt-catalysed addition of diphenylacetylene to 1,2-diaryldiazenes and their acid-catalysed rearrangement to N-anilinoindoles - Heinemann, Frank Wilhelm; et al. (Journal of Organometallic Chemistry, 1997)
Keywords: Stilbenylazobenzene; Hydride complexes; Indoles; Alkyne insertion; 2; 3-dihydrocinnoline; Diaryldiazene; Cobalt catalysis

Transition metal complexes with sulfur ligands .124. Coordination of C and S ligands on metal-carbene-thiolate fragments [M('S2C')] [M = Ni(II), Pd(II), Pt(II); 'S2C'(2-) = 1,3-imidazolidinyl-N,N'-bis-(2-benzenethiolate) (2-)]. [M(L) ('S2C')] complexes where L = CN-, CH3-, COCH3-, CNBu, CR2, SH- and SR- (R = Et, Ph, ortho-C6H4NH2) - Sellmann, Dieter; Allmann, Christof; Heinemann, Frank Wilhelm; Knoch, Falk; Sutter, Jörg (Journal of Organometallic Chemistry, 1997)
A series of [M(L)('S2C')] complexes (M = Ni-II, Pd-II, Pt-II) containing the carbene dithiolate ligand 'S2C'(2-)= 1,3-imidazolidinyl-N,N'-bis(2-benzenethiolate)(2-) and various C and S co-ligands have been synthesized. When treated with KCN, n-butylisonitrile, the electron-rich olefin R2C=CR2 [= bis(1,3-diphenylimidazolidine-2-ylidene) LiMe, thiolates such as SEt-, SPh- or o-SC6H4NH2, and hydrogen sulfide, the parent complex [Ni('S2C')](2).DMF (1) yields the corresponding anionic or neutral [Ni(L)('S2C')] complexes which were isolated as [K-2(Kryptofix5)(THF)(2)(mu-OH2)][Ni(CN)('S2C') (2), [Ni(CNBu)('S2C')] (3), [Ni(CR2)('S2C')] (4), (Li(12-crown-4)(2) ][Ni(CH3)('S2C')] (5), [NBu4][Ni(SEt)('S2C')].THF (6), [Na(15-crown-5)][Ni(SPh)('S2C')] (7), [Na(15-crown-5)][Ni(o-SC6H4NH2)('S2C')].0.5THF (8), and [Na(15-crown-5)][Ni(SH)('S2C')] (9). Analogous complexes of 9 have also been obtained with Pd (10) and Pt (II). The complexes were characterized by elemental analyses and the usual spectroscopic methods. X-ray structure determinations of 2, 3, 4, 6, 9 and 10 revealed that the [M('S2C')I fragments are stereochemically very rigid, being little influenced by the different co-ligands L. The four-coordinate metal centers exhibit an approximately square-planar coordination geometry. The 'S2C'(2) ligands show a characteristic propeller-like twist resulting from positioning the C-6 rings of the 'S2C' unit above and below the coordination plane. As evidenced by the molecular structures of 9 vs. 10, this twist can vary, and the 'S2C'(2-) ligand is flexible enough to accommodate also larger metal ions than Ni-II. Complexes 9-11 belong to the rare cases of isolable SH complexes. The complexes 2-11 exhibit a remarkable thermal stability (4 is stable up to 220 degrees C), and the [M('S2C')] fragments so far proved inert towards decomposition. When treated with Bronsted acids, the general reactivity feature of all anionic [M(L)('S2C')] complexes is release of HL and regeneration of the parent complexes [M('S2C')](2). The methyl complex [Li(4-crown-4)(2)][Ni(CH3)('S2C')] (5) is one of the rare examples in which a methyl ligand binds to an [NiS] center. While the parent complex [Ni('S2C')](2).DMF (1) proved unreactive towards CO, 5 readily inserts CO yielding the highly reactive acetyl derivative [Ni(COCH3)('S2C')](-). This complex could not be isolated, but its formation was established by spectroscopic methods and by its subsequent reaction with PhSH yielding, among other products, the thioester CH3COSPh. The model character of this reaction sequence for acetyl-CoA synthesis catalyzed by CO dehydrogenases is discussed. (C) 1997 Elsevier Science S.
Keywords: nickel; palladium; platinum; carbene ligand; sulphur ligand; methyl ligand; crystal structures

Transition Metal Complexes with Sulfur Ligands. 130.(1) Synthesis, Structure, and Reactivity of the Sulfur-Rich Ruthenium Hydride Complexes [Ru(H)(PR(3))('S(4)')](-) and the eta(2)-H(2) Complex [Ru(H(2))(PCy(3))('S(4)')] (R = Ph, (i)Pr, Cy; 'S(4)'(2-) = 1,2-Bis((2-mercaptophenyl)thio)ethane(2-)). - Sellmann, Dieter; Gottschalk-Gaudig, Torsten; Heinemann, Frank Wilhelm (Inorganic Chemistry, 1998)
Hydride and eta(2)-H(2) ruthenium complexes with sulfur-rich coordination spheres were synthesized. Substitution of either DMSO or PPh(3) in [Ru(DMSO)(PR(3))('S(4)')] and [Ru(PPh(3))(2)('S(4)')] by hydride anions from LiAlH(4) or NaBEt(3)H yielded [Ru(H)(PR(3))('S(4)')](-) complexes (R = (i)Pr, Ph, Cy; 'S(4)'(2)(-) = 1,2-bis((2-mercaptophenyl)thio)ethane(2-)). They were isolated as [Li(THF)(Et(2)O)][Ru(H)(PR(3))('S(4)')] (R = (i)Pr (1a), Cy (1b), Na[Ru(H)(PCy(3))('S(4)')].2BEt(3).0.5DMSO (2a), and the solvent-free Na[Ru(H)(PPh(3))('S(4)')].2BEt(3) (2b). X-ray structure determinations of 1a.0.5Et(2)O and 1b.Et(2)O showed that in both complexes pseudooctahedral [Ru(H)(PR(3))('S(4)')](-) anions are bridged to pseudotetrahedral [Li(THF)(Et(2)O)] cations via the hydride ligand and one thiolate donor of the 'S(4)'(2)(-) ligand (crystal data: 1a, monoclinic, P2(1)/n, a = 1401.6(2) pm, b = 1045.2(3) pm, c = 2590.6(4) pm, beta = 95.04(1) degrees, V = 3.780(1) nm(3), Z = 4; 1b, triclinic, P&onemacr;, a = 1264.2(1) pm, b = 1322.9(3) pm, c = 1569.5(2) pm, alpha = 88.96(1) degrees, beta = 83.48(1) degrees, gamma = 62.16(1) degrees, V = 2.3042(6) nm(3), Z = 2). Short intramolecular C-H.H-Ru contacts ( approximately 230 pm) between the hydride ligands, phosphine substituents, and lithium-coordinated Et(2)O molecules indicate "unconventional" hydrogen bonds. They potentially help to decrease the hydridic character of the hydride ligand to such an extent that no structural hydride trans influence can be observed in the solid state. In solution at room temperature, all hydride complexes 1a-2b rapidly release H(2) or HD, when treated with CH(3)OH or CD(3)OD. Low-temperature (1)H and (2)H NMR spectroscopy between -20 and -80 degrees C showed that initially eta(2)-H(2) or eta(2)-HD complexes form. Their formation explains the observed scrambling between protons and hydride ligands, which requires a heterolytic cleavage of dihydrogen. A 1:1:1 triplet at delta = -6.5 ppm ((1)J(HD) = 32 Hz, (2)J(PH) = 5 Hz) and a relaxation time of T(1)(min) = 4 ms (-60 degrees C, 270 MHz) firmly established the formation of the eta(2)-dihydrogen complexes. The reversibility of H(2) release and uptake by [Ru(PCy(3))('S(4)')] fragments and the heterolytic cleavage of H(2) in [Ru(eta(2)-H(2))(PCy(3))('S(4)')] was further ascertained by the reaction of [Ru(DMSO)(PCy(3))('S(4)')] with H(2) in the presence of NaOMe, yielding the [Ru(H)(PCy(3))('S(4)')](-) anion. The relevance of the complexes and their reactions for the heterolytic H(2) activation at the transition metal sulfur sites of hydrogenases is discussed.

Transition Metal Complexes with Sulfur Ligands. 130.1 Synthesis, Structure, and Reactivity of the Sulfur-Rich Ruthenium Hydride Complexes [Ru(H)(PR3)('S4')]- and the η 2-H2 Complex [Ru(H2)(PCy3) ('S4')] (R = Ph, iPr, Cy; 'S4'2- = 1,2-Bis ((2-mercaptophenyl)thio)ethane(2-)) - Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry, 1998)

Transition-Metal Complexes with Sulfur Ligands. 132.(1) Electron-Rich Fe and Ru Complexes with [MN(2)S(3)] Cores Containing the New Pentadentate Ligand 'N(2)H(2)S(3)'(2)(-) (= 2,2'-Bis(2-mercaptophenylamino)diethyl Sulfide(2-)). - Sellmann, Dieter; Utz, J.; Heinemann, Frank Wilhelm (Inorganic Chemistry, 1999)
The new pentadentate amine thioether thiolate ligand 'N(2)H(2)S(3)'-H(2) (= 2,2'-bis(2-mercaptophenylamino)diethyl sulfide) (3) was synthesized in order to obtain iron and ruthenium complexes with high electron densities at the metal centers. The reaction of 'N(2)H(2)S(3)'(2)(-) with Fe(2+) yielded the dinuclear high-spin complex [Fe('N(2)H(2)S(3)')](2) (5). Complex 5 added CO to give the low-spin complex [Fe(CO)('N(2)H(2)S(3)')] (6) whose low frequency nu(CO) (1932 cm(-)(1)) indicates a high electron density at the iron center and a strong Fe-CO bond. However, 6 is labile and readily dissociates CO in solution. Treatment of suitable ruthenium precursor complexes with 'N(2)H(2)S(3)'(2)(-) yielded [Ru(CO)(PCy(3))('N(2)H(2)S(3)')] (7), [Ru(PPr(3))(2)('N(2)H(2)S(3)')] (8), [Ru(PR(3))('N(2)H(2)S(3)')] (R = Pr (9), Ph (10)), and [Ru(NO)('N(2)HS(3)')] (13). In complexes 7 and 8, 'N(2)H(2)S(3)'(2)(-) acts as a tetradentate ligand. When heated in solution, complex 8 dissociates one PPr(3) ligand to give 9. Complex 13 contains the trisanionic 'N(2)HS(3)'(3)(-) resulting from deprotonation of one amine NH function. All [Ru(L)('N(2)H(2)S(3)')] complexes proved inert toward dissociation of the Ru-L bonds. The NH functions of [M(L)('N(2)H(2)S(3)')] complexes are acidic and show H(+)/D(+) exchange reactions with D(2)O. Methylation of the thiolate donors in 10 yielded the thioether derivative [Ru(PPh(3))('N(2)H(2)S(3)'-Me(2))]I(2) (11) whose PPh(3) ligand is as inert to substitution as that of 10. Complex 11 can reversibly be deprotonated to give [Ru(PPh(3))('N(2)HS(3)'-Me(2))]I (12). NMR spectroscopic investigations showed that the deprotonation/protonation reactions of 11 and 12 are stereoselective. In contrast, protonation of 13 with HBF(4) gives two diastereomers of the corresponding [Ru(NO)('N(2)H(2)S(3)')]BF(4) salt (14). X-ray structure analyses of 5, 6, 9, and 11 and NMR spectra showed that the 'N(2)H(2)S(3)'(2)(-) ligand and its derivatives bind to the metal centers in the same fashion which combines fac and mer coordination of the donor atoms. The [MN(2)S(3)] cores of all complexes have an analogous C(1) symmetrical structure in which both the two N and the two terminal S donors assume cis positions.

Transition metal complexes with sulfur ligands, 134 [(+)] - Synthesis of the tetradentate thioether amine and thioether thiolate ligands 1,2 bis(2 aminophenylthio)phenylene and 1,2 bis(2 mercaptophenylthio)phenylene and some representative six-coordinate ruthenium and osmium complexes - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 1999)
Keywords: Cleavage reactions; C-S cleavage; Osmium; Ligand synthesis; S ligands; Ruthenium

Transition metal complexes with sulfur ligands, 135 [(+)] - Electron- rich Fe and Ru complexes with the new trisamine dithiolate ligand 'N3H3S2'-H2-bis(2-mercaptophenylamino)diethylamine] - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 1999)
Keywords: Iron; Pentadentate ligands; N ligands; S ligands; Ruthenium

Transition metal complexes with sulfur ligands, 138. - Synthesis, structures, and reactions of sulfur-rich nickel and platinum complexes with [MS3] and [MNS2] cores - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 1999)
Keywords: C-S cleavage; Nickel complexes; Hydride complexes; S ligands; Platinum complexes

Transition metal complexes with sulfur ligands, 139. - Synthesis and exchange reactions of sulfur-rich nickel and palladium [M(L)('S3')] complexes ['S3'2- = bis(2-mercaptophenyl)sulfide(2-)] - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2000)
Keywords: Azide; Nickel complexes; Exchange reactions; S ligands; Palladium complexes; Sulfinylimide

Transition metal complexes with sulfur ligands, 140 - Mononuclear Ni, Pd and Pt complexes with ' S-3 '(2-) thioether thiolate and HNPnPr(3) phosphorane imine ligands [' S-3 '(2-) = bis(2-mercaptophenyl])sulfide (2-)] - Sellmann, Dieter; Geipel, Franz; Heinemann, Frank Wilhelm (European Journal of Inorganic Chemistry, 2000)
Reaction of the trinuclear [M('S-3')](3) complexes M = Ni (4), Pd (5), Pt (6); 'S-3'(2-) = bis (2-mercaptophenyl) sulfide (2-) with HNPnPr(3) yielded the new phosphorane inline complexes [M(NHPnPr(3))('S-3')] M = Ni (1), Pd (2), Pt (3). The complexes 1-3 have been completely characterized and are rare examples of mononuclear phosphorane imine complexes with late transition metals. Spectroscopic and structural results indicate that the HNPnPr(3) ligands favor the ylidic structure when binding to [M('S-3')] fragments. X-ray structure determinations showed that [M(NHPrP3)('S-3')] complexes associate through N-H ... S(thiolate) bridges to give centrosymmetric dimers.
Keywords: phosphorane imine; sulfur ligands; nickel; palladium; platinum

Transition metal complexes with sulfur ligands, 142. - Inert and labile [Ru(L)('pyS4')] complexes with rigid [RuNS4] cores and trans-thiolate donors [L = PPh3, PEt3, DMSO, CO, NO+, N2H4; 'pyS4'2- = 2,6-Bis(2- mercaptophenylthio)dimethylpyridine(2-)] - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2000)
Keywords: Exchange reactions; Sulfur ligands; Ruthenium

Transition metal complexes with sulfur ligands, 143. Coordination of CO, NO, N2H2, and other nitrogenase relevant small molecules to sulfur-rich ruthenium complexes with the new ligand 'tpS4'2- = 1,2-bis(2- mercaptophenylthio)phenylene(2-) - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2000)
Keywords: Diazene; Ruthenium; Hydrazine; S ligands

Transition metal complexes with sulfur ligands, 145 [1]. [Ru(NO)('pybuS4')]br, a complex with [Ru(NO)(NS4)] core, activated CH2 groups, and interionic interactions in the solid state ('pybuS4'2- = 2,6-Bis(2-mercapto-3,5-di-tert-butylphenylthio)dimethylpyridine(2-)) Übergangsmetallkomplexe mit schwefelliganden, 145 [1]. [Ru(NO)('pybuS4')]br, ein komplex mit [Ru(NO)(NS4)]-gerüst, aktivierten CH2-gruppen und interionischen wechselwirkungen im festkörper ['pybuS4'2- = 2,6-Bis(2-mercapto-3,5-di-ter-butyl-phenylthio)dimethylpyridin(2-)] - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2000)
Keywords: Ruthenium nitrosyl complexes; Interionic interaction; Sulfur ligands

Transition metal complexes with sulfur ligands. 149: Mononuclear carbene dithiolate [Ni(NHX)(′S2C′)] Complexes with HNX = HNPiPr3 or HNSPh2 coligands (′S2C′2- = 1,3-imidazolidinyl-N,N′-bis(2-benzenethiolate)(2-)) - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Anorganische und Allgemeine Chemie, 2001)
Keywords: Carbene complexes; Nickel; Hydrogen bond

Transition Metal Complexes with Sulfur Ligands, CXXXIII [1]. Synthesis, Structure, and Properties of New FeII Complexes with [FeN2S2] Cores Übergangsmetallkomplexe mit Schwefelliganden, CXXXIII [1]. Synthese, Struktur und Eigenschaften neuer FeII-Komplexe mit [FeN2S2]-Gerüsten - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 1998)
Keywords: Cyclic Voltammetry; Amine Ligands; Phosphane Ligands; Iron Sulfur Complexes; X-Ray Data

Transition metal complexes with sulfur ligands, part 146: Activation and desoxygenation of CO, CO2, and SO2 with sulfur-rich azide and amide [Ni(L)(′S3′)] complexes (′S3′2- = Bis(2-mercaptophenyl)sulfide (2-)) - Heinemann, Frank Wilhelm; et al. (Chemistry - A European Journal, 2000)
Keywords: Activation; Nickel; N ligands; S ligands

Transition Metal Complexes with Sulfur Ligands. Part 147. Synthesis, reactivity and structure of strictly homologous 18 and 19 valence electron iron nitrosyl complexes - Sellmann, Dieter; Blum, Nicole; Heinemann, Frank Wilhelm; Heß, Bernd Artur (European Journal of Chemistry, 2001)
UnivIS-Import:2017-03-24:Pub.2001.forsch.sonder.sfb583.transi

Transition Metal Complexes with Sulfur Ligands. Part 150. [Ru(N_2_)(P^i^Pr_3_)(N_2_Me_2_S_2_)]: Coordination of molecular N_2_ to metal thiolate cores under mild conditions - Sellmann, Dieter; Hautsch, Barbara; Rösler, Annette; Heinemann, Frank Wilhelm (Angewandte Chemie, 2001)
UnivIS-Import:2017-03-24:Pub.2001.forsch.sonder.sfb583.transi_46

Transition metal complexes with sulfur ligands. Part CLV. Structural and spectroscopic characterization of hydrogen bridge diastereomers of [my-N_2_H_2_Fe(PR_3_)('tpS_4_') - Sellmann, Dieter; Blum, David; Heinemann, Frank Wilhelm (Inorganica Chimica Acta)
UnivIS-Import:2017-03-24:Pub.2002.forsch.sonder.sfb583.transi

Transition metal complexes with sulfur ligands Part CXLIV. Square planar nickel complexes with NiS 4 cores in three different oxidation states: Synthesis, X-ray structural and spectroscopic studies - Sellmann, Dieter; Binder, H.; Häußinger, Daniel; Heinemann, Frank Wilhelm; Sutter, Jörg (Inorganica Chimica Acta, 2000)
The reaction of 'S-bu(2)'(2-) = 3,5-ditertiarybutyl-1,2-benzenedithiolate(2 -) with Ni(ac)(2). 4H(2)O and subsequently AsPh4Cl, yielded (AsPh4)(2)[Ni('S-bu(2)')(2)] (1). Complex 1 is extremely air sensitive and oxidized rapidly to give (AsPh4)[Ni('S-bu(2)')(2)] (2). The anion of 2 could be further oxidized by iodine to give neutral [Ni('S-bu(2)')(2)] (3). Complexes 1, 2 and 3 contain nickel in the formal oxidation states + 2, + 3 and + 4, and could be completely characterized by X-ray structure determination and spectroscopic methods. The results indicate that the oxidation of 1–>2–>3 concerns electrons residing in molecular orbitals having [NiS4] character. No evidence could be obtained for an involvement of the benzene rings or an electron delocalization beyond the [NiS4] core. This conclusion corresponds with the reactivity of 3 versus 2 and 1 towards protons and CO. While 3 is inert to the attack of H+ and CO, 2 and 1 exhibit rapid reactions to give 'S-bU(2)'-H-2 and either nickel-chioro complexes or Ni(CO)(4). (C) 2000 Elsevier Science S.A. All rights reserve
Keywords: nickel thiolate complexes; high oxidation states

Transition metal complexes with sulfur ligands Part CXXIX. Retention and reactivity of the [Fe=NH=NH=Fe] chromophore in the iron sulfur diazene complex [μ-N2H2Fe(PPr3) ('S4') - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta)
Keywords: Crystal structures; Iron complexes; Diazene complexes; Sulfur complexes

Transition metal complexes with sulfur ligands. Part CXXVII. Azido, halido and nitrido ruthenium complexes with sulfur-rich coordination spheres - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 1998)
Keywords: Azido complexes; Nitrido complexes; Halido complexes; Sulfur complexes; Ruthenium complexes

Transition metal complexes with sulfur ligands Part CXXV . Synthesis and characterization of hydrido and chloro complexes with rhodium sulfur cores - Heinemann, Frank Wilhelm; et al. (Inorganica Chimica Acta, 1998)
Keywords: Crystal structures; Rhodium complexes; Hydride complexes; Sulfur ligand complexes

Transition metal complexes with sulfur ligands. (see abstract) - Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry, 1999)

Transition Metal Complexes with Sulphur Ligands, Part 151 [1]. Ligand Enforced Configurations and Low-Spin States of [FeNS_4_] Cores in [Fe^II^(L)('pyS_4_')] Complexes with sigma and sigma-pi Ligands (L = N_2_H_4_, pyridine, PMe_3_, PnPr_3_; 'pyS_4_'^2-^ = 2,6-bis(2-mercaptophenylthiomethyl)pyridine (2-)) - Sellmann, Dieter; Blum, Nicole; Heinemann, Frank Wilhelm (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2001)
UnivIS-Import:2017-03-24:Pub.2001.forsch.sonder.sfb583.transi_4

Transition of TiO2 nanotubes to nanopores for electrolytes with very low water contents - Wei, Wei; Hauser, Christina; Wei, Wei; Berger, Steffen; Hauser, Christina; Meyer, Karsten; Yang, Mingjun; Schmuki, Patrik (Electrochemistry Communications, 2010)
Over the past decade, the electrochemical formation of self-organized nanotube layers in dilute fluoride containing electrolytes has been studied intensively. In the present work, we show that by anodization of Ti in similar electrolytes but containing only very low water contents, the formation of ordered TiO nanoporous structures can be observed. I.e., the water content in the electrolyte is the critical factor that decides whether self-ordered oxide tubes or pores are formed. This supports the concept that tube formation originates from ordered porous oxide by a "pore-wall- splitting" mechanism. © 2010 Elsevier B.V. All rights reserved.

Transmetalation from Magnesium–NHCs—Convenient Synthesis of Chelating π-Acidic NHC Complexes - Messelberger, Julian; Grünwald, Annette; Stegner, Philipp; Senft, Laura; Heinemann, Frank Wilhelm; Munz, Dominik (Inorganics, 2019)
The synthesis of chelating N-heterocyclic carbene (NHC) complexes with considerable -acceptor properties can be a challenging task. This is due to the dimerization of free carbene ligands, the moisture sensitivity of reaction intermediates or reagents, and challenges associated with the workup procedure. Herein, we report a general route using transmetalation from magnesium-NHCs. Notably, this route gives access to transition-metal complexes in quantitative conversion without the formation of byproducts. It therefore produces transition-metal complexes outperforming the conventional routes based on free or lithium-coordinated carbene, silver complexes, or in situ metalation in dimethyl sulfoxide (DMSO). We therefore propose transmetalation from magnesium-NHCs as a convenient and general route to obtain NHC complexes.
CRIS-Team WoS Importer:2019-06-28

Trapping of soluble, KCl-stabilized Cu(i) hydrides with CO2 gives crystalline formates - Grasruck, Alexander; Parla, Giorgio; Lou, Lisha; Langer, Jens; Neiß, Christian; Herrera, Alberto; Frieß, Sibylle; Görling, Andreas; Schmid, Günter; Dorta, Romano (Chemical Communications, 2023)
Cu(i)-Hydrido complexes supported by dibenzo[b,f]azepinyl P-alkene hybrid ligands and stabilized by electrostatic interactions in a Cu-H⋯KCl⋯BR3 arrangement can be trapped with CO2 at low temperature to afford Cu(i)-formates. The complexes are isolable with and without a pendant BEt3 group and show strong Cu-O and weak B-O interactions.
CRIS-Team Scopus Importer:2023-12-15

Tricyclic Sulfoxide-Alkene Hybrid Ligands for Chiral Rh(I) Complexes: The "matched" Diastereomer Catalyzes Asymmetric C-C Bond Formations - Nikol, Alexander; Zhang, Ziyun; Chelouan, Ahmed; Falivene, Laura; Cavallo, Luigi; Herrera, Alberto; Heinemann, Frank Wilhelm; Escalona, Ana; Frieß, Sibylle; Grasruck, Alexander; Dorta, Romano (Organometallics, 2020)
Deprotonation of phenyldibenzo[b,f]tropylidene (8) with LDA/t-BuOK followed by quenching with either diastereomer of inexpensive glucose-based t-Bu-sulfinate (R)- or (S)-11 affords a sulfoxide-alkene hybrid ligand as the diastereomeric pairs (SS,SC)-9/(SS,RC)-10 and (RS,RC)-9/(RS,SC)-10, respectively, which via chromatographic/recrystallization may be separated into the four isomers. The optically pure diastereomeric ligands (SS,SC)-9 and (SS,RC)-10 react with [RhCl(coe)2]2 to form the dinuclear complexes (RS,SC)-11 and (RS,RC)-12, respectively, in which the bidentate ligands coordinate the metal centers through the sulfur and alkene donor functions. These complexes catalyze the conjugate addition of arylboronic acids to cyclic Michael acceptors with enantioselectivities of up to 99% ee. DFT calculations show the preponderant influence of planar chirality of the ligand alkene function. The enantioselectivity switch observed between (RS,SC)-11 and (RS,RC)-12 is explained by the inverted cis-trans coordinations of the substrate molecules in catalytic steps.
CRIS-Team Scopus Importer:2020-04-03

Trinuclear Mixed-Valent Oxo-Centered Iron Complexes: Fully Localised, Partially and Fully Delocalised Valencies - Saalfrank, Rolf; Scheurer, Andreas; Schünemann, Volker; Trautwein, A. X. (Mössbauer Spectroscopy and Transition Metal Chemistry - Fundamentals and Applications, 2011)

Trinuclear [NiFe] Clusters as Structural Models for [NiFe] Hydrogenase Active Sites - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2005)
[Fe(CH3COCH=CHPh)(CO)3] reacts with [Ni(′S 4′)]x (x = 1, 2) or [Ni(′S4C 3Me2′)] [′S4′2- = 1,2-bis(2-mercaptophenylthio)-ethane(2-), ′S4C 3Me2′2- = 1,3-bis(2-mercaptophenylthio)- 2,2-dimethylpropane(2-)] to afford trinuclear [NiFe] clusters [Ni(′S 4′)Fe(CO)32] (1) and [Ni(′S 4C3Me2′)Fe(CO)3 2] (2) and the dinuclear FeIIFe0 complex [Fe(CO)(′S4C3Me2′)Fe(CO) 3] (3). Clusters 1 and 2 have Ni-Fe bond lengths similar to those of active or reduced states of [NiFe] hydrogenases, a sulfur-dominated coordination sphere of Ni and iron-bound CO. Therefore, 1 and 2 may serve as structural model complexes for the [NiFe] hydrogenase active site. Combination of the prime;S4C3Me2′ ligand with FeCl 2·4H2O yielded [Fe(′S4C 3Me2′)]2 (4), the dinuclearity of which suggests that the ′S4C3Me2′ ligand is less flexible than its ethylene-bridged derivative, which affords a tetrameric [Fe(′S4′)]4 complex reported earlier. Compound 4 reacts with 2 equiv. of CO to give [Fe(CO)(′S 4C3Me2′)]2 (5), which like 4 is only sparingly soluble in all common organic solvents. Complex 5 easily loses CO even if stored in the solid state. [Fe(CH3COCH= CHPh)(CO) 3] reacts with 5 to afford 3 as the only product. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
UnivIS-Import:2017-03-24:Pub.2005.forsch.sonder.sfb583.trinuc
Keywords: Carbonyl ligands; Cluster compounds; Iron; Nickel; S ligands

Trinuclear oxo-centered iron and iron/nickel clusters - Ligand-controlled homo/hetero valency - Heinemann, Frank Wilhelm; et al. (European Journal of Inorganic Chemistry, 2005)
Keywords: Heteronuclear complexes; Mixed-valent complexes; Iron; Trinuclear complexes; Nickel

Tuning Magnetic and Photophysical Properties of Luminomagnetic Metal-Organic Framework Composites in an Inverse Core-Satellite Structure - Seuffert, Marcel T.; Granath, Tim; Kasper, Thomas; Maile, Ruben; Pujales Paradela, Rosa; Prieschl, Johannes; Wintzheimer, Susanne; Mandel, Karl; Mueller-Buschbaum, Klaus (ChemPlusChem, 2022)
Luminomagnetic composites have been synthesized that allow for an individual tuning of luminescence intensity, chromaticity and magnetization by combination of superparamagnetic, citrate-stabilized iron oxide nanoparticles with the luminescent MOFs (3)(infinity)[Ln(2)(BDC)(3)(H2O)(4)] (Ln=Eu, Tb; BDC2-=terephthalate). The components are arranged to a concept of inverse structuring compared to previous luminomagnetic composites with MOF@magnetic particle (shell@core) composition so that the luminescent MOF now acts as core and is covered by magnetic nanoparticles forming the satellite shell. Thereby, the magnetic and photophysical properties are individually tuneable between high emission intensity (1.2 center dot 10(6) cps mg(-1)) plus low saturation magnetization (6 emu g(-1)) and the direct opposite (0.09 center dot 10(6) cps mg(-1); 42 emu g(-1)) by adjusting the particle coverage of the MOF. This is not achievable with a core-shell structure having a magnetic core and a dense MOF shell. The composition of the composites and the influence of different synthesis conditions on their properties were investigated by SEM/EDX, PXRD, magnetization measurements and photoluminescence spectroscopy.
CRIS-Team WoS Importer:2023-01-27

Tuning spin-spin coupling in quinonoid-bridged dicopper(II) complexes through rational bridge variation - Schweinfurth, David; Khusniyarov, Marat; Bubrin, Denis; Hohloch, Stephan; Su, Cheng-Yong; Sarkar, Biprajit (Inorganic Chemistry, 2013)

Tuning the electronic properties in ruthenium-quinone complexes through metal coordination and substitution at the bridge - Das, Hari Sankar; Schweinfurth, David; Fiedler, Jan; Khusniyarov, Marat; Mobin, Shaikh. M.; Sarkar, Biprajit (Chemistry - A European Journal, 2014)
Keywords: ruthenium; spectroelectrochemistry; non-innocent ligands; redox chemistry; NIR absorptions

Tuning the light absorption of a molecular vanadium oxide system for enhanced photooxidation performance - Forster, Johannes; Rösner, Benedikt; Khusniyarov, Marat; Streb, Carsten (Chemical Communications, 2011)

Tuning the Morphology of Spray-Dried Supraparticles: Effects of Building Block Size and Concentration - Zhou, Huanhuan; Pujales Paradela, Rosa; Groppe, Philipp; Wintzheimer, Susanne; Mandel, Karl (Particle & Particle Systems Characterization, 2022)
Tuning the morphology of supraparticles can crucially influence their final properties and is, thus, important for their application in chemical, pharmaceutical, and food industries. The present study reveals how varied nanoparticle sizes, concentrations, and weight ratios in multicomponent dispersions influence the morphology of supraparticles assembled by these nanoparticle building blocks via spray-drying. In a droplet containing monodisperse nanoparticles, smaller nanoparticles form a coherent elastic shell due to lower cohesive forces. As the solvent enclosed in the shell evaporates less easily due to the narrow pores between the nanoparticles, this ultimately results in rather non-spherical supraparticles, while larger nanoparticles tend to yield spherical supraparticles. When small nanoparticles outweigh large ones in binary or trinary dispersions, the small nanoparticles form the outer shell that shrinks into a mushroom cap-like shape upon drying of the spray-droplet, while larger nanoparticles stay in the center of the droplet, resulting in non-spherical supraparticles. Furthermore, the findings give a more systematic insight into structures that potentially arise from multimodal-sized building blocks, thus, paving the way to tune the supraparticle morphology upon spray-drying, when working with more complex, multicomponent dispersions.
CRIS-Team WoS Importer:2022-09-23

Tuning the oxidation level, the spin state, and the degree of electron delocalization in homo- and heteroleptic bis(alpha-diimine)iron complexes - Khusniyarov, Marat; Weyhermüller, Thomas; Bill, Eckhard; Wieghardt, Karl (Journal of the American Chemical Society, 2009)

Two new imidazole-based heteroscorpionate ligands - Fischer, Nina; Heinemann, Frank Wilhelm; Burzlaff, Nicolai (European Journal of Inorganic Chemistry, 2009)
The syntheses of two novel imidazole-based N,N,O and N,N,S ligands, 2,2-bis(N-methylimidazol-2-yl)ethanol (Hbmie) and lithium bis(N-methylimidazol- 2-yl)dithioacetate Li[bmidta], are described. The coordination properties of the two new ligands are studied by the synthesis of rhenium(I) and ruthenium(II) complexes. Single crystal X-ray diffraction analyses of Hbmie, Li[bmidta] together with bis(N-methylimidazol-2-yl)methane (bmim) and [Re(bmie)(CO) ] are provided, too. ©Wiley-VCH Verlag GmbH and Co. KGaA, 69451 Weinheim, Germany, 2009.

Two-Photon Absorption in Pentacene Dimers: The Importance of the Spacer Using Upconversion as an Indirect Route to Singlet Fission - Garoni, Eleonora; Zirzlmeier, Johannes; Basel, Bettina; Hetzer, Constantin; Kamada, Kenji; Guldi, Dirk Michael; Tykwinski, Rik (Journal of the American Chemical Society, 2017)
In this proof of concept study, we show that intramolecular singlet fission (iSF) can be initiated from a singlet excited state accessed by two-photon absorption, rather than through a traditional route of direct one-photon excitation (OPE). Thus, iSF in pentacene dimers 2 and 3 is enabled through NIR irradiation at 775 nm, a wavelength where neither dimer exhibits linear absorption of light. The adamantyl and meta-phenylene spacers 2 and 3, respectively, are designed to feature superimposable geometries, which establishes that the electronic coupling between the two pentacenes is the significant structural feature that dictates iSF efficiency.
CRIS-Team Scopus Importer:2022-04-14

Übergangsmetallkomplexe mit Schwefelliganden CXXIV. Koordination von C-und S-Liganden an Metall - Carben - Thiolat-Fragmente - Sellmann, Dieter; Allmann, Christof; Heinemann, Frank Wilhelm; Knoch, Falk; Sutter, Jörg (Journal of Organometallic Chemistry, 1997)

Umpolung in a Pair of Cobalt(III) Terminal Imido/Imidyl Complexes - Mao, Weiqing; Fehn, Dominik; Heinemann, Frank Wilhelm; Scheurer, Andreas; Van Gastel, Maurice; Jannuzzi, Sergio A.; Debeer, Serena; Munz, Dominik; Meyer, Karsten (Angewandte Chemie International Edition, 2022)
Reaction of the CoI complex [(TIMMNmes)CoI](PF6) (1) (TIMMNmes=tris-[2-(3-mesityl-imidazolin-2-ylidene)-methyl]amine) with mesityl azide yields the CoIII imide [(TIMMNmes)CoIII(NMes)](PF6) (2). Oxidation of 2 with [FeCp2](PF6) provides access to a rare CoIII imidyl [(TIMMNmes)Co(NMes)](PF6)2 (3). Single-crystal X-ray diffractometry and EPR spectroscopy confirm the molecular structure of 3 and its S= (Formula presented.) ground state. ENDOR, X-ray absorption spectroscopy and computational analyses indicate a ligand-based oxidation; thus, an imidyl-radical electronic structure for 3. Migratory insertion of one ancillary NHC to the imido ligand in 2 gives the CoI N-heterocyclic imine (4) within 12 h. Conversely, it takes merely 0.5 h for 3 to transform to the CoII congener (5). The migratory insertion in 2 occurs via a nucleophilic attack of the imido ligand at the NHC to give 4, whereas in 3, a nucleophilic attack of the NHC at the electrophilic imidyl ligand yields 5. The reactivity shunt upon oxidation of 2 to 3 confirms an umpolung of the imido ligand.
CRIS-Team Scopus Importer:2022-08-12
Keywords: Cobalt; Imidyl Radical; N-Heterocyclic Carbene; Terminal Imido; Umpolung

Unconventional singlet fission materials - Ullrich, Tobias; Munz, Dominik; Guldi, Dirk Michael (Chemical Society Reviews, 2021)
Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states. As such, it constitutes an exciton multiplication generation process, which is currently at the focal point for future integration into solar energy conversion devices. Beyond this, various other exciting applications were proposed, including quantum cryptography or organic light emitting diodes. Also, the mechanistic understanding evolved rapidly during the last year. Unfortunately, the number of suitable SF-chromophores is still limited. This is per se problematic, considering the wide range of envisaged applicability. With that in mind, we emphasize uncommon SF-scaffolds and outline requirements as well as strategies to expand the chromophore pool of SF-materials. This journal is
CRIS-Team Scopus Importer:2021-04-02

Unexpected reactivity resulting from modifications of the ligand periphery: Synthesis, structure, and spectroscopic properties of iron complexes of new tripodal N-heterocyclic carbene (NHC) ligands - Vogel, Carola; Heinemann, Frank Wilhelm; Khusniyarov, Marat; Meyer, Karsten (Inorganica Chimica Acta, 2010)
The chelating ligand tris-[2-(3-aryl-imidazol-2-ylidene)ethyl]amine (TIMEN, R = aryl = 2,6-xylyl (xyl), mesityl (mes)) has provided access to reactive transition metal complexes. Here, two new tripodal N-heterocyclic carbene ligands of the TIMEN system (R = aryl = tolyl (tol), 3,5-xylyl (3,5xyl)), featuring sterically less demanding aryl substituents were synthesized. With these ligands, Fe(II) precursor complexes could be obtained, namely [(TIMEN)Fe](BF) (3) and [(TIMEN)Fe(CHCN)](PF) (7), which showed unexpected reactivity upon reduction. Treatment of the compounds with sodium amalgam yield the tris- and bis-metallated products, [(TIMEN)Fe] (4) and [(TIMEN)Fe] (8), respectively. While the Fe(III) complex 4 is relatively inert towards oxygen, the Fe(II) complex 8 is prone to oxidation. This oxidation of 8 can readily be observed in chlorinated solvents, producing the Fe(III) complex [(TIMEN )Fe](PF) (9). All new ligand imidazolium precursors and metal complexes were characterized by single crystal X-ray structure determination. © 2010 Elsevier B.V. All rights reserved.

Unexpected Trends in the Stability and Dissociation Kinetics of Lanthanide(III) Complexes with Cyclen-Based Ligands across the Lanthanide Series - Pujales Paradela, Rosa; et al. (Inorganic Chemistry, 2020)

Unified model for singlet fission within a non-conjugated covalent pentacene dimer - Basel, Bettina; Zirzlmeier, Johannes; Hetzer, Constantin; Phelan, Brian T.; Krzyaniak, Matthew D.; Seelam, Rajagopala Reddy; Brana Coto, Pedro; Horwitz, Noah E.; Young, Ryan M.; White, Fraser J.; Hampel, Frank; Clark, Timothy; et al. (Nature Communications, 2017)
When molecular dimers, crystalline films or molecular aggregates absorb a photon to produce a singlet exciton, spin-allowed singlet fission may produce two triplet excitons that can be used to generate two electron-hole pairs, leading to a predicted similar to 50% enhancement in maximum solar cell performance. The singlet fission mechanism is still not well understood. Here we report on the use of time-resolved optical and electron paramagnetic resonance spectroscopy to probe singlet fission in a pentacene dimer linked by a non-conjugated spacer. We observe the key intermediates in the singlet fission process, including the formation and decay of a quintet state that precedes formation of the pentacene triplet excitons. Using these combined data, we develop a single kinetic model that describes the data over seven temporal orders of magnitude both at room and cryogenic temperatures.

Uniform sidearm derivatisations in a tetrapodal pentaamine: Ligands with NN4O4 donor sets, and a bis(ferrocenecarbaldehyde aminal) - Heinemann, Frank Wilhelm; et al. (Zeitschrift für Naturforschung Section B-A Journal of Chemical Sciences, 2000)
Keywords: Nonadentate ligand; Nickel; Schiff base

Unique anisotropic optical properties of a highly stable metal-organic framework based on trinuclear iron(iii) secondary building units linked by tetracarboxylic linkers with an anthracene core - Vinogradov, A. V.; Milichko, V. A.; Zaake-Hertling, H.; Aleksovska, A.; Gruschinski, S.; Schmorl, S.; Kersting, B.; Zolnhofer, Eva; Sutter, Jörg; Meyer, Karsten; Lönnecke, P.; Hey-Hawkins, Evamarie (Dalton Transactions, 2016)

Unlocking the Metalation Applications of TMP-powered Fe and Co(II) bis(amides): Synthesis, Structure and Mechanistic Insights - Logallo, Alessandra; Maddock, Lewis C.H.; Mu, Manting; Gravogl, Lisa; Jin, Na; Peñas-Defrutos, Marconi N.; Meyer, Karsten; García-Melchor, Max; Hevia, Eva (Angewandte Chemie International Edition, 2024)
Typified by LiTMP and TMPMgCl.LiCl, (TMP=2,2,6,6-tetramethylpiperidide), s-block metal amides have found widespread applications in arene deprotonative metalation. On the contrary, transition metal amides lack sufficient basicity to activate these substrates. Breaking new ground in this field, here we present the synthesis and full characterisation of earth-abundant transition metals M(TMP)2 (M=Fe, Co). Uncovering a new reactivity profile towards fluoroarenes, these amide complexes can promote direct M−H exchange processes regioselectively using one or two of their basic amide arms. Remarkably, even when using a perfluorinated substrate, selective C-H metalation occurs leaving C−F bonds intact. Their kinetic basicity can be boosted by LiCl or NBu4Cl additives which enables formation of kinetically activated ate species. Combining spectroscopic and structural studies with DFT calculations, mechanistic insights have been gained on how these low polarity metalation processes take place. M(TMP)2 can also be used to access ferrocene and cobaltocene by direct deprotonation of cyclopentadiene and undergo efficient CO2 insertion of both amide groups under mild reaction conditions.
CRIS-Team Scopus Importer:2024-06-14
Keywords: amide; cobalt; fluoroarenes; iron; metalation

Unprecedented pairs of uranium (IV/V) hydroxido and (IV/V/VI) oxido complexes supported by a seven- coordinate cyclen-anchored tris-aryloxide ligand - Löffler, Sascha; Hümmer, Julian; Scheurer, Andreas; Heinemann, Frank Wilhelm; Meyer, Karsten (Chemical Science, 2022)
We present the synthesis and reactivity of a newly developed, cyclen-based tris-aryloxide ligand precursor, ,- namely cyclen(Me)(t-Bu,t-BuArOH)(3), and its coordination chemistry to uranium. The corresponding uranium(III) complex [U-III((OArt-Bu,t-Bu)(3)(Me)cyclen)] (1) was characterized by H-1 NMR analysis, CHN elemental analysis and UV/vis/NIR electronic absorption spectroscopy. Since no single-crystals suitable for X-ray diffraction analysis could be obtained from this precursor, 1 was oxidized with methylene chloride or silver fluoride to yield [(cyclen(Me)(t-Bu,t-BuArOH)(3))U-IV(X)] (X = Cl (2), F (3)), which were unambiguously characterized and successfully crystallized to gain insight into the molecular structure by single-crystal X-ray diffraction analysis (SC-XRD). Further, the activation of H2O and N2O by 1 is presented, resulting in the U(IV) complex [(cyclen(Me)(t-Bu,t-BuArOH)(3)))U-IV(OH)] (4) and the U(V) complex Rcyclen(Me)(t-Bu,t-BuArOH)(3))U-IV(O)] (6). Complexes 2, 3, 4, and 6 were characterized by H-1 NMR analysis, CHN elemental analysis, UV/vis/NIR electronic absorption spectroscopy, IR vibrational spectroscopy, and SQUID magnetization measurements as well as cyclic voltammetry. Furthermore, chemical oxidation of 3, 4, and 6 with AgF or AgSbF6 was achieved leading to complexes Rcyclen(Me)(t-Bu,t-BuArOH)(3))U-V(F)(2)] (5), Rcyclen(Me)(t-Bu,t-BuArOH)(3))U-V(OH)][SbF6] (7), and Rcyclen(Me)(t-Bu,t-BuArOH)(3))U-V(O)][SbF6] (8). Finally, reduction of 7 with KC8 yielded a U(IV) complex, spectroscopically and magnetochemically identified as K [(cyclen(Me)(t-Bu,t-BuArOH)(3))U-IV(O)].
CRIS-Team WoS Importer:2022-09-16

Unprecedented triphosphinine iron interactions: Intramolecular electron transfer, reactivity round a corner, and a low-activated ring element exchange reaction - Eggers, Karin; Heinemann, Frank Wilhelm; Hennemann, Matthias; Clark, Timothy; Binger, Paul; Zenneck, Ulrich (Comptes Rendus Chimie, 2010)
2,4,6-Tri-tert-butyl-1,3,5-triphosphinine (7) was combined with 1,5-COD or 2,4-di-tertbutyl-1,3-diphosphete to form iron pi-complexes. The ligands of highly reactive [(2,4-di-tert-butyl-1,3-diphosphete)(2,4,6-tri-tert-butyl-1,3,5-triphosphinine)Fe] (8) are formed by cyclooligomerization of tert-butylphosphaalkyne (3) under the influence of the iron atom. 8 rearranges spontaneously to yield penta-tert-butyl-pentaphosphaferrocene (9) as the isolable product. An intramolecular electron transfer product [(1,5-COD)(eta(6)-1,3,5-triphosphacyclohexa-2,5-dine-1,4-diyl)Fe((2+))] (12) is obtained with 1,5-COD. Addition of [(CO)(5)Cr(THF)] initiates an interligand hydrogen transfer to form [(eta(5)-trihydropentalenyl)Fe(mu,1-3-eta-4,5,6-trihydro-1,3,5-triphosphinine)Cr(CO)(5)] (13) Extensive DFT calculations of isolated and reactive species, and several possible intermediates agree with the experimental observations and revealed for the first time a possible reaction sequence, which allows a low-activated exchange of ring elements between the ligands of sandwich complex 8 to form 9. The process is based on the specific combination of the metal and its heterocyclic pi-ligands. Both, singlet and triplet spin states play an important role in the process. (C) 2010 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Keywords: Phosphorus; Iron; pi-Complexes; Rearrangement; Density functional calculations

Unraveling the electronic structures of low-valent naphthalene and anthracene iron complexes: X-ray, spectroscopic, and density functional theory studies - Schnoeckelborg, Eva-Maria; Khusniyarov, Marat; De Bruin, Bas; Hartl, Frantisek; Langer, Thorsten; Eul, Matthias; Schulz, Stephen; Poettgen, Rainer; Wolf, Robert (Inorganic Chemistry, 2012)

Untersuchungen zum elektronischen Einfluß von Organoliganden. XIII. Synthese und Charakterisierung von 2-funktionalisierten Vinylrhodoximen. - Aisa, A. M. A.; Heinemann, Frank Wilhelm; Steinborn, Dirk (Zeitschrift für Anorganische und Allgemeine Chemie, 1996)

Unusual Dinitrogen Binding and Electron Storage in Dinuclear Iron Complexes - Sorsche, Dieter; Miehlich, Matthias; Searles, Keith; Gouget, Guillaume; Zolnhofer, Eva; Fortier, Skye; Chen, Chun Hsing; Gau, Michael; Carroll, Patrick J.; Murray, Christopher B.; Caulton, Kenneth G.; Khusniyarov, Marat; et al. (Journal of the American Chemical Society, 2020)
A rare example of a dinuclear iron core with a non-linearly bridged dinitrogen ligand is reported in this work. One-electron reduction of [(tBupyrr2py)Fe(OEt2)] (1) (tBupyrr2py2- = 2,6-bis((3,5-di-tert-butyl)pyrrol-2-yl)pyridine) with KC8 yields the complex [K]2[(tBupyrr2py)Fe]2(μ2-η·1:η·1-N2) (2), where the unusual cis-divacant octahedral coordination geometry about each iron and the η·5-cation-πcoordination of two potassium ions with four pyrrolyl units of the ligand cause distortion of the bridging end-on μ-N2 about the FeN2Fe core. Attempts to generate a Et2O-free version of 1 resulted instead in a dinuclear helical dimer, [(tBupyrr2py)Fe]2 (3), via bridging of the pyridine moieties of the ligand. Reduction of 3 by two electrons under N2 does not break up the dimer, nor does it result in formation of 2 but instead formation of the ate-complex [K(OEt2)]2[(tBupyrr2py)Fe]2 (4). Reduction of 1 by two electrons and in the presence of crown-ether forms the tetraanionic N2 complex [K2][K(18-crown-6)]2(tBupyrr2py)Fe]2(μ2-η·1:η·1-N2) (5), also having a distorted FeN2Fe moiety akin to 2. Complex 2 is thermally unstable and loses N2, disproportionating to Fe nanoparticles among other products. A combination of single-crystal X-ray diffraction studies, solution and solid-state magnetic studies, and 57Fe Mössbauer spectroscopy has been applied to characterize complexes 2-5, whereas DFT studies have been used to help explain the bonding and electronic structure in these unique diiron-N2 complexes 2 and 5.
CRIS-Team Scopus Importer:2020-06-02

Unusual oxidative stability of a multidentate primary amine ligand: Facile synthesis of the oxo-bridged diiron(III) complex - Heinemann, Frank Wilhelm; et al. (Inorganic Chemistry Communications, 2004)
Keywords: Hydroxo complex; Oxo complex; Iron; Tetrapodal pentadentate ligand

Uranium chemistry between phobia and enthusiasm - Hauser, Christina; Meyer, Karsten (Nachrichten aus der Chemie, 2007)
Keywords: CARBON-MONOXIDE; URANYL-ION; COMPLEX; DINITROGEN

Uranium Going the Soft Way: Low-Valent Uranium(III) Coordinated to an Arene-Anchored Tris-Thiophenolate Ligand - Pividori, Daniel Maximilian; Miehlich, Matthias; Kestel, Benedikt; Heinemann, Frank Wilhelm; Scheurer, Andreas; Patzschke, Michael; Meyer, Karsten (Inorganic Chemistry, 2021)
The synthesis of a tripodal, S-based ligand, namely the mesitylene-anchored, tris-thiophenolate-functionalized (mes(Me,AdArS)3)3- (1)3-, and its coordination chemistry with low-valent uranium to form [UIII((SArAd,Me)3mes)] (1-U) are reported. Single-crystal X-ray diffraction analysis reveals a C3-symmetric molecular structure. Full characterization of 1-U was performed using nuclear magnetic resonance, UV-vis-NIR electronic absorption, and electron paramagnetic resonance spectroscopies as well as SQUID magnetometry, thus confirming the U(III) oxidation state. Alternating current magnetic studies show that 1-U exhibits single-molecule magnet behavior at low temperatures in a non-zero external field. Comparison of these results to those of the previously reported mesitylene-anchored complexes, [UIII((OArAd,Me)3mes)] and [UIII((OArtBu,tBu)3mes)], indicates a drastic change in the electronic structure when moving from phenolate-based ligands to thiophenolate-based 1, which is further discussed by means of computational analysis (NBO, DFT, and QTAIM). Despite the U-O bonds being stronger, a much higher covalency was found for the U-S analogue.
CRIS-Team Scopus Importer:2021-11-19

Uranium Hydridoborates: Synthesis, Magnetism, and X-ray/Neutron Diffraction Structures - Braunschweig, Holger; Gackstatter, A.; Kupfer, Thomas; Radacki, Krzysztof; Franke, Sebastian; Meyer, Karsten; Fucke, K.; Lemee-Cailleau, M-H. (Inorganic Chemistry, 2015)
While uranium hydridoborate complexes containing the [BH4]- moiety have been well-known in the literature for many years, species with functionalized borate centers remained considerably rare. We were now able to prepare several uranium hydridoborates (1-4) with amino-substituted borate moieties with high selectivity by smooth reaction of [Cp∗2UMe2] (Cp∗ = C5Me5) and [Cp′2UMe2] (Cp′ = 1,2,4-tBu3C5H2) with the aminoborane H2BN(SiMe3)2. A combination of nuclear magnetic resonance spectroscopy, deuteration experiments, magnetic SQUID measurements, and X-ray/neutron diffraction studies was used to verify the anticipated molecular structures and oxidation states of 1-4 and helped to establish a linear tridentate coordination mode of the borate anions. (Chemical Equation Presented).
CRIS-Team Scopus Importer:2020-09-14

Uranium(III) complexes with bulky aryloxide ligands featuring metal-arene interactions and their reactivity toward nitrous oxide - Franke, Sebastian; Tran, Ba L.; Heinemann, Frank Wilhelm; Hieringer, Wolfgang; Mindiola, Daniel J.; Meyer, Karsten (Inorganic Chemistry, 2013)
We report the synthesis and use of an easy-to-prepare, bulky, and robust aryloxide ligand starting from inexpensive precursor materials. Based on this aryloxide ligand, two reactive, coordinatively unsaturated U(III) complexes were prepared that are masked by a metal-arene interaction via δ-backbonding. Depending on solvent and uranium starting material, both a tetrahydrofuran (THF)-bound and Lewis-base-free U(III) precursor can easily be prepared on the multigram scale. The reaction of these trivalent uranium species with nitrous oxide, NO, was studied and an X-ray diffraction (XRD) study on single crystals of the product revealed the formation of a five-coordinate U(V) oxo complex with two different molecular geometries, namely, square pyramidal and trigonal bipyramidal. © 2013 American Chemical Society.

Uranium(III)-mediated C-C-coupling of terminal alkynes: Formation of dinuclear uranium(IV) vinyl complexes - Kosog, Boris; Kefalidis, Christos E.; Heinemann, Frank Wilhelm; Maron, Laurent; Meyer, Karsten (Journal of the American Chemical Society, 2012)
The previously reported uranium(III) complex [(( ArO) N)U (DME)] (1; Ad = adamantane, DME = 1,2-dimethoxyethane) reacts with the terminal bis-alkynes 1,7-octadiyne or 1,6-heptadiyne in C-C-coupling reactions to form the uranium(IV) vinyl complexes [(( ArO) N)U (μ- η :η -1,2-(CH) -cyclohexane)] (2) and [(( ArO) N)U (μ- η :η -1,2-(CH) -cyclopentane)] (3). With the monoalkynes 1-hexyne or 4- butyl-phenylacetylene, the complexes [(( ArO) N)U (μ- η (C1):η (C4)-2- Bu-1,3-octadiene)] (4) and [(( ArO) N)U (μ- η (C4):η (C1)-1,3-di-(p- Bu-phenyl) butadiene))] (5), are formed. These are the first four examples of uranium vinyl complexes that are reported and crystallographically characterized. In addition, detailed DFT calculations are presented to establish a possible mechanism for their formation and explain the differences found for the coordination of the hydrocarbon fragments. In contrast to a previously proposed monometallic pathway for catalytic hydroamination of alkynes and alkyne dimerization involving a uranium vinyl intermediate at uranium(III) complexes, the calculations clearly support a bimetallic mechanism, since its transition states are energetically the most favored. © 2012 American Chemical Society.

Uranium(IV) halide (F-, Cl-, Br-, and I-) monoarene complexes. - Halter, Dominik; la Pierre, Henry Storms; Heinemann, Frank Wilhelm; Meyer, Karsten (Inorganic Chemistry, 2014)
The syntheses of four nearly isostructural uranium(IV) monoarene complexes, supported by the arene anchored tris(aryloxide) chelate, [((Ad,Me)ArO)3mes](3-), are reported. Oxidation of the uranium(III) precursor [(((Ad,Me)ArO)3mes)U], 1, in the presence of tetrahydrofuran (THF) results in THF coordination and distortion of the equatorial coordination sphere to afford the uranium(IV) η(6)-arene complexes, [(((Ad,Me)ArO)3mes)U(X)(THF)], 2-X-THF, (where X = F, Cl, Br, or I) as their THF adducts. The solvate-free trigonally ligated [(((Ad,Me)ArO)3mes)U(F)], 2-F, was prepared and isolated in the absence of coordinating solvents for comparison.

Uranium(IV) terminal hydrosulfido and sulfido complexes: insights into the nature of the uranium-sulfur bond - Rosenzweig, Michael; Scheurer, Andreas; Lamsfus, Carlos A.; Heinemann, Frank Wilhelm; Maron, Laurent; Andrez, Julie; Mazzanti, Marinella; Meyer, Karsten (Chemical Science, 2016)
Herein, we report the synthesis and characterization of a series of terminal uranium(IV) hydrosulfido and sulfido complexes, supported by the hexadentate, tacn-based ligand framework ((ArO)-Ar-Ad,Me)(3)tacn(3-) (= trianion of 1,4,7-tris(3-(1-adamantyl)-5-methyl-2-hydroxybenzyl)-1,4,7-triazacyclononane). The hydrosulfido complex [(((ArO)-Ar-Ad,Me)(3)tacn) U-SH] (2) is obtained from the reaction of H2S with the uranium(III) starting material [(((ArO)-Ar-Ad,Me)(3)tacn) U] (1) in THF. Subsequent deprotonation with potassium bis(trimethylsilyl) amide yields the mononuclear uranium(IV) sulfido species in good yields. With the aid of dibenzo-18-crown-6 and 2.2.2-cryptand, it was possible to isolate a terminal sulfido species, capped by the potassium counter ion, and a "free" terminal sulfido species with a well separated cation/anion pair. Spectroscopic and computational analyses provided insights into the nature of the uranium-sulfur bond in these complexes.

Uranium-ligand multiple bonding in uranyl analogues, [L=U=L]n+, and the inverse trans influence - la Pierre, Henry Storms; Meyer, Karsten (Inorganic Chemistry, 2013)
The societal importance of uranium complexes containing the uranyl moiety [O=U=O] continues to grow with the ongoing international nuclear enterprise and associated accumulating legacy waste. Further studies of the electronic structure of uranyl and its analogues are imperative for the development of crucial technologies, including lanthanide/actinide extractants and chemical and environmental remediation methodologies. Actinide oxo halides are a subset of the growing class of actinyl (uranyl) analogues. The understanding of their electronic structures links the detailed spectroscopic studies of uranyl, indicating the role of the pseudocore 6p orbitals in U-O bonding, to hypotheses about the 6p orbitals' role in the chemical bonding of uranyl analogues. These actinide oxo halides are a very small class of actinide compounds that present the inverse trans influence (ITI). This class of complexes was, until recently, limited to two crystallographically characterized compounds, namely, [UClO][PPh] and [PaCl O][NEt]. These complexes are important because they give a readily and clearly defined experimental observable: the difference between the M-X and M-X (here X = Cl) bond lengths in the solid state. This bond metric is a sensitive probe for the role of 6p, 6d, and 5f orbitals, as well as electrostatic interactions, in determining their electronic structure. This Viewpoint Article reviews the theoretical, experimental, and synthetic work on the ITI in actinide complexes and contextualizes it within broader studies on the electronic structure of uranyl and its analogues. Furthermore, our recent work on the ITI in high-valent uranium(V/VI) oxo and imido complexes is described as a whole. This work builds on the extant synthetic literature on the ITI and provides design parameters for the synthesis and characterization of high-valent uranium-ligand multiple bonds. © 2012 American Chemical Society.

Uranium-mediated carbon dioxide activation and functionalization - Lam, Oanh P.; Meyer, Karsten (Polyhedron, 2012)
The importance of CO activation and functionalization is undeniable, given the surge of effort in this area in the last few decades. Uranium complexes have begun to emerge as excellent candidates for small molecule activation, often exemplified by their varied and unprecedented chemistry with CO . In this review, we present accounts of carbon dioxide activation and functionalization mediated by uranium complexes in various oxidation states from low-valent (+3), mid-valent (+4), to high-valent (+5). © 2011 Elsevier Ltd. All rights reserved.

Uranium-mediated electrocatalytic dihydrogen production from water - Halter, Dominik; Heinemann, Frank Wilhelm; Bachmann, Julien; Meyer, Karsten (Nature, 2016)
Depleted uranium is a mildly radioactive waste product that is stockpiled worldwide. The chemical reactivity of uranium complexes is well documented, including the stoichiometric activation of small molecules of biological and industrial interest such as H2O, CO2, CO, or N-2 (refs 1-11), but catalytic transformations with actinides remain underexplored in comparison to transition-metal catalysis(12-14). For reduction of water to H-2, complexes of low-valent uranium show the highest potential, but are known to react violently and uncontrollably forming stable bridging oxo or uranyl species(15). As a result, only a few oxidations of uranium with water have been reported so far; all stoichiometric(2,3,16,17). Catalytic H-2 production, however, requires the reductive recovery of the catalyst via a challenging cleavage of the uranium-bound oxygen-containing ligand. Here we report the electrocatalytic water reduction observed with a trisaryloxide U(iii) complex [(((ArO)-Ar-Ad,Me)(3)mes)U] (refs 18 and 19)-the first homogeneous uranium catalyst for H-2 production from H2O. The catalytic cycle involves rare terminal U(iv)-OH and U(v)= O complexes, which have been isolated, characterized, and proven to be integral parts of the catalytic mechanism. The recognition of uranium compounds as potentially useful catalysts suggests new applications for such light actinides. The development of uranium-based catalysts provides new perspectives on nuclear waste management strategies, by suggesting that mildly radioactive depleted uranium-an abundant waste product of the nuclear power industry-could be a valuable resource.

Uranium-Mediated Peroxide Activation and a Precursor toward an Elusive Uranium cis-Dioxo Fleeting Intermediate - Hartline, Douglas; Löffler, Sascha; Fehn, Dominik; Kasper, Joseph M.; Heinemann, Frank Wilhelm; Yang, Ping; Batista, Enrique R.; Meyer, Karsten (Journal of the American Chemical Society, 2023)
The activation of chalcogen-chalcogen bonds using organometallic uranium complexes has been well documented for S-S, Se-Se, and Te-Te bonds. In stark contrast, reports concerning the ability of a uranium complex to activate the O-O bond of an organic peroxide are exceedingly rare. Herein, we describe the peroxide O-O bond cleavage of 9,10-diphenylanthracene-9,10-endoperoxide in nonaqueous media, mediated by a uranium(III) precursor [((Me,AdArO)3N)UIII(dme)] to generate a stable uranium(V) bis-alkoxide complex, namely, [((Me,AdArO)3N)UV(DPAP)]. This reaction proceeds via an isolable, alkoxide-bridged diuranium(IV/IV) species, implying that the oxidative addition occurs in two sequential, single-electron oxidations of the metal center, including rebound of a terminal oxygen radical. This uranium(V) bis-alkoxide can then be reduced with KC8 to form a uranium(IV) complex, which upon exposure to UV light, in solution, releases 9,10-diphenylanthracene to generate a cyclic uranyl trimer through formal two-electron photooxidation. Analysis of the mechanism of this photochemical oxidation via density functional theory (DFT) calculations indicates that the formation of this uranyl trimer occurs through a fleeting uranium cis-dioxo intermediate. At room temperature, this cis-configured dioxo species rapidly isomerizes to a more stable trans configuration through the release of one of the alkoxide ligands from the complex, which then goes on to form the isolated uranyl trimer complex.
CRIS-Team Scopus Importer:2023-05-19

Uranium-mediated reductive conversion of CO2 to CO and carbonate in a single-vessel, closed synthetic cycle - Schmidt, Anna-Corina; Nizovtsev, Alexey; Scheurer, Andreas; Heinemann, Frank Wilhelm; Meyer, Karsten (Chemical Communications, 2012)
The new neopentyl (Neop)-substituted tris(aryloxide) U(iii) complex [((ArO)tacn)U] reacts with CO to form CO and the bridging carbonate complex [(( ArO)tacn)U(μ-CO )]. The uranium(iv) bridging oxo [((ArO) tacn)U(μ-O)] has been determined to be the intermediate in this reaction. For the first time, both U(iv) complexes can be reduced back to the U(iii) starting material. Thus, with KC as reductant, [((ArO)tacn)U] engages in a synthetic cycle, in which CO is converted to CO and CO . © 2012 The Royal Society of Chemistry.

Uranium Tetrakis-Aryloxide Derivatives Supported by Tetraazacyclododecane: Synthesis of Air-Stable, Coordinatively-Unsaturated U(IV) and U(V) Complexes. - Hümmer, Julian; Heinemann, Frank Wilhelm; Meyer, Karsten (Inorganic Chemistry, 2017)
We present the synthesis, characterization, and one-electron oxidation of two uranium(IV) complexes, coordinated to the cyclen-anchored tetrakis(aryloxide) ligands tetrakis-hydroxybenzyl-1,4,7,10 tetraazacyclododecane, (R,RArOH)4cyclen; R = tBu, Me. The new uranium(IV) and (V) complexes exhibit an eight-coordinate, tetragonal ligand environment, effecting exceptional stability of the coordinatively unsaturated uranium compounds. Cyclic voltammetry studies reveal redox events ranging from tri- to hexavalent species, covering an electrochemical window of ∼4 V.

Using Diamagnetic Yttrium and Lanthanum Complexes to Explore Ligand Reduction and C-H Bond Activation in a Tris(aryloxide)mesitylene Ligand System - Palumbo, Chad T.; Halter, Dominik; Voora, Vamsee K.; Chen, Guo P.; Ziller, Joseph W.; Gembicky, Milan; Rheingold, Arnold L.; Furche, Filipp; Meyer, Karsten; Evans, William J. (Inorganic Chemistry, 2018)
[Y(N(SiMe3)2)3] reacts with (Ad,MeArOH)3mes to form the Y3+ complex [((Ad,MeArO)3mes)Y], 1-Y. This complex reacts with potassium metal in the presence of 2.2.2-cryptand to give a cocrystallized mixture of [K(2.2.2-cryptand)][((Ad,MeArO)3mes)Y], 2-Y, and [K(2.2.2-cryptand)][((Ad,MeArO)3mes)YH], 3-Y. The electron paramagnetic resonance spectrum of this crystalline mixture exhibits an isotropic signal at 77 K (giso = 2.000, Wiso = 1.8 mT), suggesting that 2-Y is best described as a Y3+ complex of the tris(aryloxide)mesitylene radical ((Ad,MeArO)3mes)4-. Evidence of the hydride ligand in 3-Y was obtained by 89Y-1H heteronuclear multiple quantum coherence NMR spectroscopy, and a coupling constant of JYH = 93 Hz was observed. A single crystal of 3-Y was also obtained in pure form and structurally characterized for comparison with the crystal data on the mixed component 2-Ln/3-Ln crystals. The origin of the hydride in 3-Ln is unknown, but further studies of the reduction of 1-La, previously found to form 2-La, revealed a possible source. Ligand-based C-H bond activation and loss of hydrogen can occur under reducing conditions to form a tetraanionic ligand derived from ((Ad,MeArO)3mes)3-, as observed in [K(2.2.2-cryptand)][((Ad,MeArO)3(C6Me3(CH2)2CH)La], 4-La.
CRIS-Team Scopus Importer:2020-09-14

Using PMHS for Catalytic Hydrosilylation with Dimeric Iron Complexes Featuring Mesoionic Carbene Ligands - Stroek, Wowa; Rowlinson, Nathalie A.V.; Keilwerth, Martin; Pividori, Daniel Maximilian; Meyer, Karsten; Albrecht, Martin (Organometallics, 2024)
While the reduction of unsaturated bonds is well established by catalytic hydrogenation reactions using H2, alternative approaches are appealing for environmental and safety reasons. One of these methods is the catalytic hydrosilylation reaction, which becomes environmentally very friendly when using polymethylhydrosiloxane (PMHS), a waste product from the silicon industry, as a hydrosilylation agent. Here, we report the synthesis and catalytic activity of a range of iron triazolylidene complexes for the hydrosilylation of carbonyls using PMHS with unprecedented turnover numbers up to 72,000. Various functional groups on the substrate aromatic ring are tolerated, including CN, Br, OMe, and NMe2 substituents. The hydrosilylation is not restricted to benzylic ketones and aldehydes, esters, and amides are also converted. Rather remarkable for hydrosilylation, ketones are converted faster than aldehydes. Intermolecular competition experiments suggest that the active catalyst is formed by the coordination of a ketone, which rationalizes the origin of this untypical substrate reactivity trend.
CRIS-Team Scopus Importer:2024-06-28