DFT STUDY OF VANADYL ACETYLACETONATE COMPLEXES WITH BENZIMIDAZOLE DERIVATIVES AND 2-MERCAPTOBENZOTHIAZOLE

The geometric and electronic structures of the mixed-ligand complexes [VO(AcAc)2MBT], [VO(AcAc)2AFBI] and [VO(AcAc)2FBI] (MBT is 2-mercaptobenzothiazole, AFBI is 2-aminophenyl-1H-benzimidazole, FBI is 2-phenylmethyl-1H-benzimidazole) were studied by density functional theory ((U)B3LYP/6-311G(d,p)/LanL2DZ, Gaussian 09W). The MBT molecule was found to be planar, whereas in AFBI and FBI the NH group is coplanar with the imidazole ring. Analysis of effective atomic charges and molecular electrostatic potential maps shows that the pyridine-type nitrogen atoms of the imidazole and thiazole rings (q = −0.355 to −0.301 e) are the most probable coordination sites for the vanadyl ion. The HOMO–LUMO energy gap of the complexes increases in the order [VO(AcAc)2AFBI] (4.32 eV) < [VO(AcAc)2MBT] (4.37 eV) < [VO(AcAc)2FBI] (4.46 eV), indicating an increase in kinetic stability and a decrease in reactivity along this series.