New polynuclear complexes, (L1)3M2
{M2
= 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
{M2
= V(IV)
(6)} and L1M2Cp2
{M2
= Ti(III)
(10)} with L1
=
(CO)5M1C{CNC(CH3)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.
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