A novel triperoxyniobium-containing polyoxoanion, SiW9(NbO2)3O377−: synthesis, characterization, catalytic allylic epoxidations with H2O2 and preliminary kinetic studies

The synthesis and characterization of the previously unknown SiW9(NbO2)3O377−, a novel composition of matter containing three adjacent NbvO2 peroxide groups, is described. Also reported is a survey of the catalytic epoxidation of seven olefinic substrates with 30% aqueous H2O2 using this heteropolyanion as a precatalyst. Additionally, the preliminary kinetic evidence presented indicates that SiW9(NbO2)3O377− serves as a catalyst precursor to the true catalyst, a catalytically active W, Nb or polyoxoanion fragment.