HOMOGENEOUS CATALYSIS BY TRANSITION-METAL OXYGEN ANION CLUSTERS

This review provides a thorough discussion of homogeneous catalysis by transition metal oxygen anion clusters (polyoxometalates), with a focus on mechanism. The primary catalysts examined are mixed addenda and d-electron-transition-metal-substituted polyoxometalate (TMSP) complexes. The unusual versatility and tunability of these catalysts and their compatibility with environmentally and economically attractive conditions (solvents, oxidants, etc.) are outlined. A general compilation of the reactions, including catalytic electrooxidations or electroreductions, reported to date is given. Selected examples involving different classes of catalysts, different organic substrates and transformations, and mechanistic information are covered.