Multidimensional CuII incorporated POMs [K2ICuII(en)2(β-Mo8O26)]n and [K2ICu3II(H2O)10(W12O40)0.2(H2O)]n: Syntheses, structures and catalytic epoxidation

Two Cu-II incorporated polyoxometalate compounds, [(K2CuII)-Cu-I(en)(2)(beta-Mo8O26)](n) (1) and [(K2Cu3II)-Cu-I(H2O)(10)(W12O40)center dot 2(H2O)](n) (2), have been synthesized and structurally characterized. In complex 1, the Mo8O264- anion shows an archetypal beta-type octamolybdate that contains eight {MoO6} subunits which are further attached by a (KO8)-O-I unit to present a 1D chain. Consecutive 1D layers are connected by a mononuclear [Cu(en)(2)O-2](2+) subunit to generate a 2D framework in the crystallographic ab plane. In complex 2, the W12O4O8- anion is a typical Keggin-type polyoxo anion containing twelve {WO6} octahedra which are alternately coordinated to (KO4)-O-I tetrahedra to generate a 1D chain. These 1D layers are interconnected by [Cu(H2O)](2+) synchronously to form a 2D framework in the crystallographic ac plane. Catalytic activity studies of complex 1 gave 91% styrene conversion with 72% epoxide selectivity and 85% cyclohexene conversion with 65% epoxide selectivity and those for complex 2 showed 88% styrene conversion with 70% epoxide selectivity and 81% cyclohexene conversion with 63% epoxide selectivity. (C) 2019 Published by Elsevier Ltd.