Assembly of Cu/Ag-quinoxaline-polyoxotungstate hybrids: Influence of Keggin and Wells–Dawson polyanions on the structure

In order to investigate the influence of Keggin and Wells–Dawson polyoxometalates on the resultant structure, four new organic–inorganic hybrid compounds [Cu4(qx)5(SiW12O40)] (1), [Cu6(qx)6(P2W18O62)(H2O)1.5]·4.5H2O (2), [Ag4(qx)4(SiW12O40)(H2O)]·H2O (3), [Ag6(qx)6(P2W18O62)]·8H2O (4) (qx=quinoxaline) were synthesized and structurally characterized by single-crystal X-ray diffraction. In 1, the 2D layers are linked by the SiW12O404− (SiW12) anions to construct a 3D framework. When the Wells–Dawson type P2W18O626− (P2W18) is used, 2 is prepared, in which the 1D helical chains are connected by P2W18 to form a 3D network. In 3, two kinds of 1D metal–organic chains are connected by SiW12 clusters to construct a 3D framework. In 4, there are also two kinds of 1D chains one kind of 1D chain combines with P2W18 by the AgO weak interaction and the other kind is just metal–organic chain. In addition, the electrochemistry properties of compounds 1–4 have been studied.