In situ FT-IR Study of Polynuclear Peroxo Complexes Formed in a H2O2-Cerium(IV) Decatungstate Anion (CeW10O368-) Reacting System

Abstract

Isopoly and heteropoly molybdenum- and tungstenpolyoxometalates have been widely applied to the syntheses of epoxides from olefins and of carbonium compounds from alcohols with the use of H2O2 as a very selective catalyst, Some of the formed peroxo complexes have generally been believed to play an important role in the reacting process as a key species, and thus many investigators have tried to determine their structures and behaviors using various kinds of in situ spectroscopic techniques. Recently, we have found an interesting catalytic activity of the sodium lanthanidedecatungstates, Ce(IV)-, Nd(III)-, and Sm(III)-W10O36n- (LnW10), for the H2O2 decomposition and H2O2 oxidation of cyclohexanol. In the H2O2-cerium(IV) decatungstate (CeW10) reacting system, the formation of the peroxo complex and its reversible behaviors have been successfully observed with the use of in situ FT-Raman spectroscopy, and its unique catalytic activity for the H2O2 oxidation of various primary and secondary alcohols has been elucidated, In an effort to obtain more information about the structural features of the peroxo complex, in situ spectroscopic measurements, FT-IR and 183W-NMR, were used under the H2O2-CeW10 reaction conditions. Here we wish to report a novel and unique structure of the peroxo complex and its reversible behavior as deduced from such measurements.