electrochemistry, thermalanalysis, and theoretical study of vanadyl schiff base complexes

the vo(iv) complexes of tridentate ono schiff base ligands derived from 2- aminobenzoicacid and salicylaldehyde derivatives were synthesized and characterized by ir, uv–vis and elemental analysis. electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. a good linear correlation was observed between the oxidation potentials and the electron-withdrawing character of the substituents on the schiff bases, showed the following trend: meo < h < br < no2. the thermogravimetry (tg) and differential thermoanalysis (dta) of the synthesized complexes were carried out in the range of 20–700 °c. all of the complexes decomposed in three steps. the thermal decomposition pathways were closely related to the nature of the schiff base ligands and preceded via first-order kinetics. the structures of compounds were determined by ab initio calculations. the optimized molecular geometry was calculated at the b3lyp/6-31g(d) level. the results suggested that, in the complexes, v(iv) ion was in square-pyramid or tbp (trigonal bipyramidal) no4 coordination geometry. also the bond lengths and angles were studied and compared.