Hydrothermal Synthesis,Crystal Structure and Characterization of a New Keggin Polyoxometalate {[Ag~I(4,4’-bipy)]_3[PW_(12)O_(40)]}·(4,4’-bipy)

A novel polyoxometalate {AgI(4,4'-bipy)]3PW12O40]}·(4,4'-bipy)·4H2O 1 has been synthesized hydrothermally and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The crystal of 1 belongs to the triclinic system, space group P1 with a = 11.3710(17), b = 12.0701(16), c = 13.1061(12) , α = 112.838(3), β = 94.545(6), γ = 99.526(4)°, V = 1614.4(4) 3, Mr = 3825.40, Z = 1, Dc = 3.935, μ = 22.289mm-1, F(000) = 1692, the final R = 0.0507 and wR = 0.1054. X-ray diffraction analysis reveals that the molecular structure of 1 consists of three coordinated cations AgI(4,4'-bipy)]+, a polyanion unit PW12O40]3-, and a discrete 4,4′-bipy molecule. Significantly, there exist two crystallographically independent silver(I) centers in 1 and all AgI(4,4'-bipy)]+ cations are linked with each other to form a one-dimensional Ag-4,4'-bipy polymer chain. The neighboring polymer chains are further interconnected to form a 3D framework by the covalent effect of silver atoms and terminal oxygen atoms of the polyanion. The electrochemical behaviors of 1 have also been studied in detail by cyclic voltammograms.