A novel two-dimensional layered Cu 2+ complex based on Dawson-like [H 3 BiW 18 O 60 ] 6- : synthesis, structure and magnetic properties.

A novel complex based on the Dawson-like [H3 BiW18 O60 ]6- , i.e. (C2 H9 N2 )2 [{Cu(C10 H8 N2 )(C2 H8 N2 )}2 (H3 BiW18 O60 )]·5.5H2 O or (enH)2 [{Cu(2,2'-bipy)(en)}2 (μ4 -H3 BiW18 O60 )]·5.5H2 O, (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 [H3 BiW18 O60 ]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 H2 SO4 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.