Trinuclear cobalt(II) sandwiched polyoxotungstobismuthate with antennal copper(II)-complex: A new method to combine hetero–transition–metallic ions

A new sandwich-type hybrid complex, Na8{Cu(im)4(H2O)}[Cu(im)4 {Na(H2O)2Co(im)}3(BiW9O33)2] · 11H2O (1) (im = imidazole), has been synthesized and structurally characterized. The polyoxoanion in 1 contains trinuclear Co2+ ions in the central belt and an antennal Cu(II)–imidazole supported complex, which firstly represents a copper(II)-complex mono-supported tungstobismuthate system containing sandwiched trinuclear cobalt(II) ions. Neighboring polyanions further connect each other by disodium ions to yield a dimeric complex. The successful synthesis of 1 opens a new approach to the combination of different kinds of transition–metal ions by virtue of lacunary Keggin-type polyoxoanions, [BiW9O33]9−, as effective linkages. The magnetic investigation for 1 indicate weak antiferromagnetic interactions for trinuclear Co(II) clusters located in the polyanions.