Spectral Investigation of Stability of the Peroxo Complexes M2[V2O2(O2)4H2O] . aq (M = N(CH3)4, N(C4H9)4) in Solutions

Abstract

Infrared spectra of solutions of M2[V2O2(O2)4H2O] . aq (M = N(CH3)4, N(C4H9)4) in heavy water and acetonitrile indicate that in concentrated solutions (c >= 0.5 mol dm-3) the asymmetric structure of the [V2O2(O2)4H2O]2- anion remains preserved for some time. Electronic spectra suggest that in more dilute solutions (c = 10-3-10-4 mol dm-3) of the M2[V2O2(O2)4H2O] . aq complexes in water and acetonitrile the dinuclear ion decomposes faster to [VO(O2)2H2O]-, followed by a relatively slow liberation of the peroxidic oxygen and formation of vanadate ions. The dinuclear complex is more stable in dilute chloroform solutions. The 51V NMR spectrum of an aqueous solution of [N(CH3)4]2[V2O2(O2)4H2O] (c = 1.3 mol dm-3) taken after a partial decomposition suggests the simultaneous presence of [V2O2(O2)4H2O]2-, [VO(O2)2H2O]-, (VnO3n)n- (n = 4, 5, 6), [HmV10O28](6-m)-, and other unidentified species.