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

The present paper reports the synthesis and characterization of some new sulfa drug based Schiff base oxovanadium(IV) complexes of composition, [VO(sal-sdz)2(H2O)]·H2O, [VO(sal-sgn)2(H2O)]·H2O, [VO(sal-snm)(H2O)]·H2O, [VO(sal-smr)2(H2O)]·H2O and [VO(dadps)(H2O)]2·2H2O, where sal-sdzH = N-(salicylidene)sulfadizine, sal-sgnH = N-(salicylidene)sulfaguanidine, sal-snmH = N-(salicylidene)sulfanilamide, sal-smrH = N-(salicylidene)sulfamerizine, sal-dadpsH2 = N,N′-bis(salicylidene)-4,4′-diaminodiphenylsulfone, respectively. Complexes, (1)-(4) were prepared by the reaction of VOSO4·5H2O with the Schiff bases in 1:2 metal-ligand ratio while complex (5) in 2:2 metal-ligand ratio in DMF-ethanol medium. The compounds so obtained were characterized by different physico-chemical studies, such as, elemental analysis, molar conductance and magnetic measurements, infrared, ESR, thermogravimetric studies, mass and electronic spectral studies. The overall IR studies conclude that the ligand in complex (1)-(4) behave as monobasic bidentate ON donor, while the ligand in the complex (5) behaves as dibasic tetradentate O2N2 donor. The 3D-molecular modeling and analysis for bond lengths and bond angles have also been carried out for two representative compounds, [VO(sal-snm)2(H2O)]·H2O (3) and [VO(dadps)(H2O)]2·2H2O (5) to substantiate the proposed structures. Based on these studies suitable octahedral structures have been proposed for these complexes.