Synthesis, crystal structure and magnetic properties of a CuII–WV/IV bimetallic complex with a novel open framework structure

Abstract

Fabricated by cyano- and alkoxyl-bridged groups, a novel three-dimensional structural compound, {[Cu₂(H₂Tea)₂]₅[W^V(CN)₈]₂[W^IV(CN)₈]·xH₂O}_∞ (H₃Tea = triethanolamine), has been formed. In the structure, there exist two kinds of W atoms and three types of Cu₂O₂ pairs. The W(1) and W(2) atoms, with oxidation states +5 and +4 respectively, are each linked to the Cu₂O₂ units through two of its eight cyanide ligands, forming two kinds of 1D zigzag chain along the c-axis (nominally the W1-chain and the W2-chain). Each W2-chain is connected to four adjacent W1-chains through a third type of Cu₂O₂ unit, leading to the formation of a three-dimensional open framework with channels generated along the [001] direction. The structure may also be viewed as being constructed from W(1)Cu₃ and W(2)Cu₄ clusters, cross-linked by μ-O bridges. The magnetic properties show that the complex displays 3D antiferromagnetic ordering below 2.2 K, although ferromagnetic interactions are present within the W(1)Cu₃ clusters. The dominant antiferromagnetic coupling at low temperature is attributed to the antiferromagnetic exchanges between the W(1)Cu₃ clusters through the alkoxyl bridges.