A functionalized polyoxometalate solid for selective oxidation of styrene to benzaldehyde

The reaction of [Na12(H2O)38][WZn{M(H2O)}2(ZnW9O34)2]·3H2O (M = Mn, Co) and Co(NO3)2·6H2O in water at 80 °C afforded red crystals of [Co(H2O)6]2{[Co(H2O)4]2[Co(H2O)5]2WZn[Co(H2O)]2(ZnW9O34)2}·10H2O (1), which has been characterized by TGA, IR, PXRD, element analysis and single crystal X-ray diffraction. The polyanion [WZn{Co(H2O)}2(ZnW9O34)2]12− in 1 is double-linked by cobalt(II) cations to extend into a 1D anionic polymeric chain of {[Co(H2O)4]2[Co(H2O)5]2WZn[Co(H2O)]2(ZnW9O34)2}4− with partial free cobalt cations. The redox active cobalt(II) sites made compound 1 an excellent catalyst for the oxidation of styrene with high styrene conversion (up to 96%) and high benzaldehyde selectivity (up to 99%).