A novel complex based on the Dawson-like [H3BiW18O60]6-, i.e. (C2H9N2)2[{Cu(C10H8N2)(C2H8N2)}2(H3BiW18O60)]·5.5H2O or (enH)2[{Cu(2,2'-bipy)(en)}2(μ4-H3BiW18O60)]·5.5H2O, (1), where enH is protonated ethane-1,2-diamine, 2,2'-bipy is 2,2'-bipyridine and en is ethane-1,2-diamine, has been synthesized hydrothermally and characterized by elemental analysis, single-crystal X-ray diffraction analysis, IR spectroscopy, powder XRD, and thermogravimetry and differential thermal analysis (TG-DTA). For (1), each [H3BiW18O60]6- anion acts as a tetradentate ligand connecting [Cu(2,2'-bipy)(en)]2+ fragments via two terminal and two bridging O atoms, forming a two-dimensional network structure. Along the a and c axes, polyoxometalate units are arranged in an AB…AB manner. The electrochemical behaviour of (1)-CPE (CPE is a carbon paste electrode) was investigated in 2 M H2SO4 solution by cyclic voltammetry (CV). The redox process of WVI/V takes place at E1/2 = -0.58 (I-I') and -0.37 V (II-II'), and at -0.04 V (III-III') for CuII/0. The magnetic properties of (1) were investigated in the range 2-300 K and indicated the existence of strong antiferromagnetic exchange interactions between the Cu2+ centres.
Keywords: Dawson-like polyoxoanion; POM; copper(II) complex; crystal structure; polyoxometalate; tungstobismuthate.