The chemistry of peroxovanadium species in aqueous solutions. Structure and reactivity of a neutral diperoxovanadium complex as provided by 51V-NMR data, ab initio calculations and kinetic results

Abstract

The addition of hydrogen peroxide to vanadium (V) precursors in aqueous acidic solutions leads to the formation of a cationic monoperoxospecies [VO(O 2)] + and an anionic diperoxocomplex [VO(O 2) 2] −, depending on the pH and on the excess of H 2O 2. The latter may undergo protonation to form the neutral complex [HVO(O 2) 2]. 51V-NMR data and ab initio calculations suggest that the neutral complex is formed via protonation of a peroxide oxygen and that in such a species, as well as in the other two peroxovanadium derivatives, the usual η 2 arrangement of the peroxo groups is maintained. The comparison of reactivity data of the three complexes in the self-decomposition reaction and in the oxidation of uracil, indicates that the neutral diperoxocomplex exhibits an oxidizing power considerably larger than that of the other two peroxovanadium species.