Oxovanadinum (IV) complexes with bidentate ligands synthesis, characterization, and comparison between experimental and theoretical

Four oxovanadium (IV) complexes with different ligands have been prepared and characterized by different spectral techniques such as (FTIR, UV–Vis., Mass) spectra, magnetic susceptibility, and DFT theoretical studies. Ligands used in this study were 8-hydroxyquinoline (HQ), oxalate (ox), dithiooximid (DTO), and 3-aminopyridine (APY). All the spectroscopic data and the theoretical calculations confirmed that the oxovanadium (IV) complexes are paramagnetic and have distorted square pyramidal structures. The FTIR spectra explain that the ligands were bidentate by (N, O), (O, O), (N, N) ligands, and monodentate (N-donor) 3-aminopyridine ligand. The mass spectral data confirmed that the complexes are mononuclear. Theoretical calculations of the free ligands and the prepared complexes have been done by using DFT calculations with proper basis sets for each other. The complexes were very stable and their energies ranged from (−775.86 to −1164.09 a.u.) and were very different from that of the free (HQ, ox, DTO and APY) ligands. The prepared complexes are more polar (5.69 to 15.54 Debye) than the free ligands. The HOMO orbitals energies of the complexes are ranged from (−0.098 to −0.392 a.u.), whereas the ligands are ranged from (−0.216 to −0.262 a.u.), and the LUMO orbitals energies of the oxocomplexes are ranged from (−0.007 to −0.296 a.u.)