Synthesis and spectral investigations of vanadium(IV/V) complexes derived from an ONS donor thiosemicarbazone ligand.

Four oxovanadium and one dioxovanadium complex with 2-hydroxyacetophenone N(4)-phenylthiosemicarbazone (H(2)L) which are represented as [VOLphen].2H(2)O (1), [VOLbipy] (2), [VOLdmbipy] (3), [VOL](2) (4) and [VO(2)HL].CH(3)OH (5) have been synthesized and characterized by elemental analyses, electronic, infrared and EPR spectral techniques. In all the complexes 1-4 the ligand coordinates through phenolic oxygen, azomethine nitrogen and thiolate sulfur. But in complex [VO(2)HL].CH(3)OH, coordination takes place in thione form instead of thiolate sulfur. All the complexes except [VO(2)HL].CH(3)OH are EPR active due to the presence of an unpaired electron. In frozen DMF at 77K, all the oxovanadium(IV) complexes show axial anisotropy with two sets of eight line patterns.