Keggin polyoxometalate-templated chair-like heptanuclear silver complex

摘要

Two isostructural Keggin-templated compounds containing a chair-like heptanuclear silver complex, [{Ag_7(Hbtz)_2(btz) _4}{PM_(12)O_(40)}]·H_2O (M = W, 1; Mo, 2) (Hbtz = benzotriazolate), have been hydrothermally synthesized and characterized by routine methods and single crystal X-ray diffraction. In the compounds 1 and 2, the Hbtz ligands present two types of coordination modes. A pentameric silver chain with two kinds of Ag?Ag weak interactions exists in the heptanuclear silver complex. The heptanuclear silver cations connect the polyoxoanions PM_(12)O_(40)~(3-) to a two-dimensional layer, and the adjacent layers are fused together by the pseudo wave-like chains, H-bonds and Ag~I-π interactions, constructing a three-dimensional net. Furthermore, electrochemical properties have been studied for compounds 1 and 2 and the two compounds display excellent electrocatalytic activities to the reduction of nitrite.