Immobilization of Keggin polyoxovanadoniobate in crystalline solids to produce effective heterogeneous catalysts towards selective oxidation of benzyl-alkanes

摘要

Two ionic organic inorganic hybrid compounds, [Cu-II(C2N2H8)(2)](4)[Cu-II(C2N2H8)(2)(H2O)(2)](2)[(PNb12O40VVO2)-V-V-O-IV]center dot(OH)(2)center dot 11H(2)O (1) and [Co-III(C2N2H8)(3)](2)[Co-III(C2N2H8)(2)(H2O)(2)](0.5)[H2.5PNb12O40 (VVO2)-V-V-O-IV]center dot 20H(2)O (2), based on P-centered dicapped polyoxoniobates and organometallic cations were isolated and structurally characterized by routine techniques. The trivalent cobalt complex-containing compound exhibits a looser arrangement compared with its divalent copper complex-containing counterpart, with a space volume of 34.9% for the former and 17.0% for the latter. The two compounds were proved to be effective in facilitating the oxidation of benzyl-alkanes to ketone products in a heterogeneous manner, evidencing the feasiblity of the strategy of self-immobilization of catalytically active, readily soluble PNb12O40(VO)(2) species in crystalline solids.