Directed synthesis of a ID double-chain polyoxometalate assembly:: {[Ag2(bppy)3][Ag(bppy)2][Ag(bppy)]2PW11Co(bppy)O39]•2H2O

A 1D double-chain assembly based on the monosubstituted Keggin polyoxometalate (POM) with pendant ligands and of formula {[Ag-2(bppy)(3)][Ag(bPPY)(2)][Ag(bppy)](2)PW11Co(bppy)O-39}.2H(2)O (1) [bppy = 5-(4-bromophenyl)-2-(4-pyridinyl)pyridine] has been synthesised and characterised. The crystals of 1 belong to the space group P1, Mr = 5801.06, a = 18.720(4) Angstrom, b = 19.474(4) Angstrom, c = 19.815(4) Angstrom, alpha = 96.30(3), beta = 96.07(3), gamma = 90.12(3)degrees, V = 7139(2) Angstrom(3), Z = 2, D-calcd = 2.699 Mg.m(-3). The final statistics based on F-2 are GOF = 1.007, R-1 = 0.0620 and wR(2) = 0.1346 for I > 2sigma(I). X-ray diffraction analysis revealed that the structure of 1 contains a 1D chain constructed from a monosubstituted tungstophosphate with one pendant conjugated ligand, five silver-bppy groups and two water molecules. The periphery of the Keggin cluster consists of five Ag-bppy groups so that a bicapped trisupporting Keggin structure is obtained. It is rare that a Keggin anion cluster is simultaneously coordinated to five transition metal atoms. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).