REACTIVITY INVESTIGATIONS OF SOME CHOSEN PEROXO-VANADIUM(V), MANGANESE(III) AND CHROMIUM(VI) COMPOUNDS

An interpretative account of the results of reactions in aqueous mediu m of a highly peroxygenated vanadium(V) complex, K[V(O2)3]. 3H(2)O, wi th different organic and inorganic substrates is presented. The reacti ons were monitored by solution EPR spectroscopy and isolation of produ cts at different stages of the reactions. Redox reactions between dipe roxide, K[VO(O-2)(2)(H2O)] and VOSO4 were conducted. The results of th e investigation suggest that secondary oxygen exchange-reaction occurs which not only depends on but also utilises the intermediates in the primary reaction during diperoxovanadate-dependent oxidation of VOSO4. In an interesting reaction tris(acetylacetonato)-manganese(III), Mn(a cac)(3), on being reacted with a hydrogen peroxide adduct, KF . H2O2, and bpy and phen afforded crystalline [Mn(acac)(2)(bpy)] and [Mn(acac) (2)(phen)], respectively. The X-ray structural analysis of [Mn(acac)(2 )(phen)] showed that the compound crystallised in orthorhombic space g roup Pbcn. The structure consists of a pseudooctahedral Mn(II) ion bei ng bound to two acac(-) (C5H5O2-) and a phen ligand with the molecule lying on two-fold axis. Reactivity profiles of two new chromium(VI) re agents viz., pyridinium fluorochromate, C5H5NH[CrO3F] (PFC), and quino linium fluorochromate C9H7NH [CrO3F] (QFC), have been presented. The c ompounds are capable of acting as both electron-transfer and oxygen-at om-transfer agents. The X-ray analysis of PFC crystals reveals that th e compound crystallises in the orthorbombic space group CmcZ(1). The s tructure consists of discrete pyridinium cations and CrO3F anions with no significant hydrogen bonding. This results in total disorder of th e pyridinium cation. The tetrahedral [CrO3F](-) ion lies on a crystall ographic mirror plane.