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Asymmetric Heterodinuclear Fe III M II (M = Zn, Cu, Ni, Fe, Mn), Co III Fe II and Fe II Co III Species: Synthesis, Structure, Redox Behavior, and Magnetism
Author(s) -
Ross Sylvia,
Weyhermüller Thomas,
Bill Eckhard,
Bothe Eberhard,
Flörke Ulrich,
Wieghardt Karl,
Chaudhuri Phalguni
Publication year - 2004
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200300533
Subject(s) - chemistry , isostructural , octahedron , crystallography , electron paramagnetic resonance , metal , ligand (biochemistry) , redox , antiferromagnetism , inorganic chemistry , analytical chemistry (journal) , crystal structure , nuclear magnetic resonance , biochemistry , physics , receptor , organic chemistry , chromatography , condensed matter physics
Reactions of an LFe III unit with an M(PyA) 3 n − ion prepared in situ, where L represents 1,4,7‐trimethyl‐1,4,7‐triazacyclononane and PyA − is the monoanion of pyridin‐2‐aldoxime, yield heterodinuclear cations of the general formula [LFe III (PyA) 3 M] 2+ , where M = Zn II ( 1 ), Cu II ( 2 ), Ni II ( 3 ), low‐spin Fe II ( 4 ) and Mn II ( 5 ). Additionally, we also prepared the diamagnetic species [LCo III (PyA) 3 Fe II ] 2+ ( 6 ). The Fe III Co II species could not be isolated because a facile intramolecular electron transfer leads to complex 7 , [LFe II (PyA) 3 Co III ] 2+ . Compounds 1 − 7 contain three oximato anions as bridging ligands and are isostructural in the sense that they all contain a terminal metal( III ) ion in a distorted octahedral environment (e.g., FeN 3 O 3 ) and a second six‐coordinate metal ion M in a mostly trigonal‐prismatic MN 6 geometry. Complexes 1 − 7 were characterized on the basis of elemental analyses, mass spectrometry, IR, UV/Vis, Mössbauer, and EPR spectroscopy, and variable‐temperature (2−295 K) magnetic susceptibility measurements. The solid‐state structures of 1 − 7 have also been determined by X‐ray crystallography. The cyclic voltammograms of the complexes reveal both ligand‐centered and metal‐centered redox processes. Analysis of the susceptibility data indicates the presence of antiferromagnetic exchange interactions that decrease in the following order: Fe III Cu II ( 2 ) > Fe III Ni II ( 3 ) > Fe III Mn II ( 5 ), as is expected. We have used X‐band EPR spectroscopy of 3 (Fe III Ni II ) at 2−6 K to establish the electronic ground state in great detail and to complement the magnetic susceptibility measurements. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)