Titanium- and zirconium-monosubstituted polyoxometalates as molecular models for studying mechanisms of oxidation catalysis

Recent developments in the application of titanium- and zirconium-monosubstituted Keggin-type polyoxometalates (Ti- and Zr-POMs) as molecular models for studying mechanisms of H2O2-based selective oxidation catalysis are reviewed. The similarity in the catalytic behavior of Ti- and Zr-POMs and heterogeneous Ti(IV) and Zr(IV) single-site selective oxidation catalysts is demonstrated. The progress on the synthesis of Ti- and Zr-POMs, studying their interaction with H2O and H2O2, and characterization of the peroxo species formed are surveyed, with special emphasis being placed on the role of protons in the activation of the peroxo species. (c) 2006 Elsevier B.V. All rights reserved.