Anionic fischer-type carbene complexes as bidentate (N,O) ligands
Date
2004
Authors
Raubenheimer H.G.
Du Toit A.
Du Toit M.
An J.
Van Niekerk L.
Cronje S.
Esterhuysen C.
Crouch A.M.
Journal Title
Journal ISSN
Volume Title
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Abstract
New polynuclear complexes, (L1)3 M2{M 2 = Cr(III) (4a, 4b), Fe(III) (5), Co(III) (8)}, (L1) 2M2(L2)2 {M2 = Co(II)(7), Ni(II) (9)}, (L1)2M2(O)L2 {M 2 = V(IV) (6)} and L1M2Cp2 {M 2 = Ti(III) (10)} with L1 = (CO)M1=C{C=NC(CH 3)=CHS}O (M1 = Cr or W) and L2 = 4-methylthiazole or THF, are described. The molecular structures of these complexes determined by X-ray diffraction show that the Fischer-type carbene complexes act as bidentate ligands towards the second metal centre, coordinating through C(carbene)-attached O-atoms and imine N-atoms of the thiazolyl groups to form five-membered chelates with the oxygen atoms in the mer configuration. Isostructural complexes have similar characteristic band patterns in their far-IR spectra. Cyclic voltammetry of selected complexes reveals the oxidation of the carbene complex ligand between 1.01 and 1.29 V. Oxidation of the central metal (M2) takes place at 0.56 and 0.86 V for 7 and 9, respectively. Three stepwise reductions of Cr(III) to Cr(0) occur for 4a and 4b in the region -0.51 to -1.58 V. These new ligand types and other variants thereof should find application in ligand design with the first metal - and other ligands attached thereto - in the carbene complex ligand, playing an important role.
Description
Keywords
Complexation, Crystallization, Cyclic voltammetry, Electrons, Gold compounds, Molecular structure, Molecular vibrations, Nuclear magnetic resonance spectroscopy, Oxidation, Oxygen, X ray crystallography, X ray diffraction analysis, Bidentate ligands, Electron pairs, Polymetallic complexes, Polynuclear complexes, Organic compounds
Citation
Dalton Transactions
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