Supramolecular structure, mixed ligands and substituents effect on the spectral studies of oxovanadium(IV) complexes of bioinorganic and medicinal relevance

Abstract

An interesting series of heterocyclic mixed ligand of oxovanadium(IV) complexes have been synthesized by the reaction of vanadium(IV) sulfate with rhodanine azo (HLn) in the presence of β-diketon (LH). The elemental analysis, magnetic moments, spectral (UV–Vis, IR, 1HNMR and ESR) with thermal studies were used to characterize the isolated complexes. The IR showed that the ligands (HLn and LH) act as a monobasic bidentate through the (NN), oxygen keto moiety and oxygen atom of the two enolate groups thereby forming a six-membered. The molar conductivities show that all the complexes are non-electrolytes. The ESR spectra indicate that the free electron is in dxy orbital. The calculated bonding parameter indicates that in-plane σ-bonding is more covalent than in-plane π-bonding. The coordination geometry around oxovanadium(IV) in all complexes is a hex-coordinated trans octahedral, with one bidentate ligand (Ln), and one bidentate ligand (L). Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectra of VO2+ reveal data that confirmed the proposed structure. The value of covalency factor (β1∗)2 and orbital reduction factor K accounts for the covalent nature of the complexes. All electronic transitions were assigned. The Hammett’s constant is also discussed.