Influence of polydentate ligands in the structure of dinuclear vanadium compounds

A review discussing general structural features of oxygen-bridged dinuclear vanadium(IV and/or V) complexes is presented, covering those that have been characterized by single-crystal X-ray diffraction. Many of these compounds contain functional Schiff bases or amines as ligands, this work illustrating the high propensity of the V center to increase its coordination number via dimerization of two tetra- or penta-coordinate monomers, if the steric and electronic control exerted by the ligands allows it. We also report the synthesis and characterization by single-crystal X-ray diffraction of two new dinuclear complexes: [((VO)-O-V[sal(R,R-chen)])(2)(mu(2)-O)(2)] and [{(VO)-O-V[mvan(S,S-chen)]}(2)(mu(2)-O)(2)]. The complexes contain tridentate ligands with O-phenolate, N-imine, and N-amine coordination to the V-V center. The molecular structures of these compounds demonstrate that they form dinuclear species in the solid state with a {OVV(mu(2)-O)(2)(VO)-O-V} core.