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Tetranuclear Copper( II ) and Nickel( II ) Complexes Incorporating a New Imidazole‐Containing Ligand
Author(s) -
Mukherjee Soumen,
Weyhermüller Thomas,
Bill Eckhard,
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.200400346
Subject(s) - chemistry , imidazolate , ligand (biochemistry) , imidazole , deprotonation , copper , nickel , medicinal chemistry , crystallography , schiff base , inorganic chemistry , electron paramagnetic resonance , stereochemistry , polymer chemistry , ion , organic chemistry , biochemistry , receptor , physics , nuclear magnetic resonance
The ligating properties of a new tridentate imidazole‐ and phenol‐containing ligand H 3 L towards nickel( II ) and copper( II ) ions have been studied. The ligand generates, in the presence of air and base, iminosemiquinone radical anions, which are not stable in the presence of the metal ions. The amine bond >C−NH− of the parent ligand becomes oxidized to >C=N− bonds upon coordination with Ni II or Cu II . The imidazole N atom becomes deprotonated and the resulting imidazolate group acts as a bridging ligand to generate tetranuclear complexes [Cu II 4 L′ 4 ] and [Ni II 4 L′ 4 ], where [L′] 2− is the dianionic new Schiff base formed after oxidation of the parent ligand. The square‐planar tetranickel( II ) complex is diamagnetic, as expected, whereas the four copper centres bridged by imidazolate anions in the complex [Cu II 4 L′ 4 ] are antiferromagnetically exchange coupled ( J = −49 cm −1 ), which has been supported by the EPR measurements. A simple magnetostructural correlation for the imidazolate‐bridged copper( II ) complexes is yet to emerge. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)