THE CHEMISTRY OF PEROXOVANADIUM SPECIES IN AQUEOUS-SOLUTIONS, STRUCTURE AND REACTIVITY OF A NEUTRAL DIPEROXOVANADIUM COMPLEX AS PROVIDED BYV-51-NMR DATA, AB-INITIO CALCULATIONS AND KINETIC RESULTS

The addition of hydrogen peroxide to vanadium (V) precursors in aqueou s acidic solutions leads to the formation of a cationic monoperoxospec ies [VO(O-2)](+) and an anionic diperoxocomplex [VO(O-2)(2)](-), depen ding on the pH and on the excess of H2O2. The latter may undergo proto nation to form the neutral complex [HVO(O-2)(2)]. V-51-NMR data and ab initio calculations suggest that the neutral complex is formed via pr otonation of a peroxide oxygen and that in such a species, as well as in the other two peroxovanadium derivatives, the usual eta(2) arrangem ent of the peroxo groups is maintained. The comparison of reactivity d ata of the three complexes in the self-decomposition reaction and in t he oxidation of uracil, indicates that the neutral diperoxocomplex exh ibits an oxidizing power considerably larger than that of the other tw o peroxovanadium species.