INVESTIGATION OF THE MANGANESE-SUBSTITUTED ALPHA-KEGGIN-HETEROPOLYANION K6SIW11O39MN(H2O) BY CYCLIC VOLTAMMETRY AND ITS APPLICATION AS OXIDATION CATALYST

The behavior of a manganese substituted alpha-Keggin silicon tungstohe teropolyanion (K6SiW11O39Mn(II)(H2O)) under electrochemical oxidation conditions was investigated by means of cyclic voltammetry in phosphat e buffer. Substitution of the water ligand by counter anions (L: H2PO4 - or HPO42-) leading to SiW11O39Mn(II)(L) was observed. Replacement of the counter anion by an aquo ligand was observed in cyclic voltammetr y by continuous cycling. After oxidation of SiW11O39Mn(II)(L) to SiW11 O39Mn(IV)(L), this counter anion L was in turn substituted by OH-. The thus formed complex SiW11O39Mn(IV)(OH) oxidizes different alcohols, t he reactivity of which decreases as follows: 1-phenyl-ethanol, benzyla lcohol > iso-propanol > ethanol.