Reaction of diperoxovanadate with vanadyl sulphate in presence of EDTA as an access to dinuclear peroxovanadates(V)

Abstract

The reaction of alkali–metal diperoxovanadate with vanadyl sulphate in the presence of EDTA afforded the dinuclear heteroligand peroxovanadates(V), A 4[V 2O 3(O 2)(EDTA)(SO 4)(H 2O)]·2H 2O, A=Na ( 1) or K ( 2). The compounds were characterised by elemental analysis, magnetic susceptibility and spectral studies. The two vanadium(V) centres in the complex ion are bridged by an oxo group and a hexadentate EDTA ligand. One of the vanadium(V) centres of the dinuclear species contains a bidentate peroxide, whereas the other vanadium centre is bonded to a unidentate sulphate and water leading to hepta-co-ordination around each vanadium(V). Oxygen release reactions and molar conductance measurements revealed that the compounds were stable in solution. The compounds were resistant to catalase and were unable to oxidise NADH or bromide. It is proposed that this dinuclear complex species corresponds to the complex formed in solution responsible for EDTA induced inhibition of oxidation of NADH and bromide by a mixture of diperoxovanadate and vanadyl.