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

Two ionic organic-inorganic hybrid compounds, [CuII (C2 N2 H8 )2 ]4 [CuII (C2 N2 H8 )2 (H2 O)2 ]2 [PNb12 O40 VV VIV O2 ]·(OH)2 ·11H2 O (1) and [CoIII (C2 N2 H8 )3 ]2 [CoIII (C2 N2 H8 )2 (H2 O)2 ]0.5 [H2.5 PNb12 O40 VV VIV O2 ]·20H2 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 PNb12 O40 (VO)2 species in crystalline solids.