New organic–inorganic hybrid compounds based on [SiNb12V2O42]12− with high catalytic activity for styrene epoxidation†
Abstract
Three new organic–inorganic hybrid compounds based on [SiNb12V2O42]12− have been obtained under hydrothermal conditions and characterized by IR, XRD, and single crystal X-ray diffraction analysis. Single crystal X-ray analysis reveals that [Cu(en)2]4[Cu(en)2(H2O)2]2[SiNb12V2O42]·14H2O (1) is constructed from [SiNb12V2O42]12− and two kinds of copper complexes, polyoxoanions in [Cu(en)2]2[Cu(en)2(H2O)]4[SiNb12V2O42]·4H2O (2) and [Cu(en)2(H2O)2]4[Cu(en)2(H2O)]2[SiNb12V2O42]·11H2O (3) are identical to compound 1, but the copper complex combinations of these two compounds are different from that of compound 1. Therefore, the final structures of the three are different from one another. All the three compounds are excellent catalysts for the epoxidation of styrene. In addition, we also synthesized an isopolyniobate K6H2Nb6O19·17H2O (4), which exhibits a 3-D structure constructed from [Nb6O19]8− and potassium clusters.