A novel Cu(II)-W(V) bimetallic assembly magnet {[Cu(en)2]3[W(CN)8]2·H2O}∞ (en = ethylenediamine) with cube-like W8Cu12 units from a coordinated anion template self-assembly reaction

Abstract

A novel molecular-based magnet of three-dimensional (3-D) cyanide-bridged bimetallic assembly, {[Cu(en)₂]₃[W(CN)₈]₂·H₂O}_∞ (1), where en = ethylenediamine, was synthesized and structurally characterized. The assembly has a three-dimensional network structure extended by three kinds of Cu^II–NC–W^V–CN–Cu^II linkages with very long axial Cu–N_cyanide interactions due to Jahn–Teller effects. The network is based on a W₈Cu₁₂ cube-like unit with eight [W(CN)₈]³⁻ anions at the corners of the distorted cube and twelve [Cu(en)₂]²⁺ cations at the middle of the edges, in which a coordination anion [W(CN)₈]³⁻ acting as template/guest is capsulated in the cavity of the W₈Cu₁₂ cube. Magnetic studies reveal that the complex displays 3-D ferromagnetic ordering over the lattice below the Curie temperature at around 2 K.