Synthesis, property and crystal structure of the new sandwich type heteropolytungstate (Hpy)4Na2H2[Cu(H2O){WO(H2O)}(WO)(AsW9O33)2]•5H2O

The new sandwich type heteropolytungstate (Hpy)(4)Na2H2[Cu(H2O) {WO(H2O)} (WO)(AsW9O33)(2)]. 5H(2)O was synthesized by the reaction of Na-12[Cu-3(H2O)(3) (AsW9O33)(2)] . xH(2)O with pyridine in pH = 1.0 aqueous solution. The single crystal X-ray diffraction study shows that the crystal belongs to monoclinic system, space group P2(1/c), with a = 2.4681(5) nm, b = 1.7474(3) nm, c = 2.4853(5) nm, beta = 118.723(3)degrees, V = 9.400(3) nm(3), Z = 4, R-1 = 0.0491. The structure of anion [Cu(H2O) {WO(H2O)} (WO) (ASW(9)O(33))(2)](8-) reveals a sandwich-like arrangement of two {alpha-B-AsW9} moieties enclosing one Cu(H2O)(2+), one WO4+ and one WO (H2O)(4+). The coordination number of Cu2+ in the sandwich anion is five, and the coordination numbers of two W6+ are 5 and 6 respectively. The formation condition of the title compound was discussed.