Mono- and dinuclear oxovanadium (IV) compounds containing VO(ONS) basic core: synthesis, structure and spectroscopic properties

Reaction of [VO(acac)2] with S-methyl 3-(2-hydroxyphenyl) methylenedithiocarbazate (H2L1) and its nitro- (H2L2) and bromo derivatives (H2L3) as tridentate heterodonor (ONS)2− ligands offers a basic VO(ONS) core. In the presence of bidentate (N,N′) donor ancillar ligands, various mono- and dinuclear oxovanadium(IV) complexes [VOL(2,2′-bipy)] (1–3), [VOL(Phen)] (4, 5) and [LOV(μ-4,4′-bipy)VOL] (4, 5) and [LOV(μ-4,4′-bipy)VOL] (6–8) were obtained. The compounds have been characterized by EPR, electronic and FAB mass spectroscopic studies. The X-ray crystal structure of a representative compound [VOL2(2,2′-bipy)] (2) is reported and shows the presence of the tridentate ONS ligand occupying the meridional sites leading to distorted octahedral geometry. The nitrogen donor, occupying an apical position has a trans-labilizing influence, resulting in elongation of the VO terminal bond. Magnetic susceptibility and EPR spectral studies indicate non-interacting nature (vbJ vb ≈ 0) of the vanadium(IV) unpaired electrons in the dinuclear complexes (6–8).