Oxovanadium(IV) complexes of bioinorganic and medicinal relevance: Synthesis, characterization and 3D molecular modeling and analysis of some oxovanadium(IV) complexes involving the O, N-donor environment of pyrazolone-based sulfa drug Schiff bases

Four new oxovanadium(IV) complexes, formed by the interaction of vanadyl sulfate pentahydrate and the Schiff bases derived from 3-methyl-1-phenyl-4-valeryl-2-pyrazolin-5-one and the sulfa drugs, N-(3′-methyl-1′-phenyl-4′-valerylidene-2′-pyrazolin-5′-one)sulfadiazine (L1H), N-(3′-methyl-1′-phenyl-4′-valerylidene-2′-pyrazolin-5′-)sulfaguanidine (L2H), N-(3′-methyl-1′-phenyl-4′-valerylidene-2′-pyrazolin-5′-one)sulphanilamide (L3H) and N′(-3′-methyl-1′-phenyl-4′-valerylidene-2′-pyrazolin-5′-one)sulphamethoxazole (L4H) in aqueous ethanol are described. The resulting complexes were characterized by elemental analyses, molar conductances, magnetic and decomposition temperature measurements, cyclic voltammetry, electron spin resonance, infrared and electronic spectral studies. They have the composition [VO(L)2]·H2O, where LH=Schiff base L1H, L2H, L3H or L4H mentioned above. A square–pyramidal structure having a slight ⋯VO⋯VO⋯ type interaction has been proposed for these complexes.