Synthesis and characterization of divalent manganese, iron, and cobalt complexes in tripodal phenolate/N-heterocyclic carbene ligand environments

Käß M, Hohenberger J, Adelhardt M, Zolnhofer E, Mossin S, Heinemann FW, Sutter J, Meyer K (2014)

Publication Type: Journal article, Original article

Publication year: 2014

Journal

Original Authors: Käß M., Hohenberger J., Adelhardt M., Zolnhofer E.M., Mossin S., Heinemann F.W., Sutter J., Meyer K.

Publisher: American Chemical Society

Book Volume: 53

Pages Range: 2460-2470

Journal Issue: 5

DOI: 10.1021/ic4024053

Abstract

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.

Authors with CRIS profile

Involved external institutions

Technical University of Denmark / Danmarks Tekniske Universitet (DTU) Denmark (DK)

How to cite

APA:

Käß, M., Hohenberger, J., Adelhardt, M., Zolnhofer, E., Mossin, S., Heinemann, F.W.,... Meyer, K. (2014). Synthesis and characterization of divalent manganese, iron, and cobalt complexes in tripodal phenolate/N-heterocyclic carbene ligand environments. Inorganic Chemistry, 53(5), 2460-2470. https://dx.doi.org/10.1021/ic4024053

MLA:

Käß, Martina, et al. "Synthesis and characterization of divalent manganese, iron, and cobalt complexes in tripodal phenolate/N-heterocyclic carbene ligand environments." Inorganic Chemistry 53.5 (2014): 2460-2470.

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