Synthesis and structural characterization of incomplete cubanes derived from [MS4Cu4Cl4]2− (MMo, W) anions

Abstract

Reaction of [Fe(bpy)3]Cl2 upon [MS4Cu4Cl4]2− (MMo, W) anions in acetonitrile-dichloromethane mixture gave incomplete cubanes. In the case of tungsten, [WS3.4O0.6Cu3(bpy)2Cl] (2a) was obtained and structurally characterized; orthorhombic, Pcab, a=13.942(9), b=10.415(3), c=33.739(4) Å, V=4893(3) Å3, Z=8, R=0.059 and Rw=0.064. The overall geometry of 2a is described as a cubane with a missing chloro-corner. Two copper atoms are tetrahedrally bound each of them being ligated to two sulfur and one bipyridine. The third copper has a trigonal environment, two sulfur atoms and a terminal chlorine. An oxygen-sulfur mixed occupancy was introduced for the terminal WS bond, supported by IR data. In the molybdenum analogue 2b the terminal double bond is pure MoO since the formula of 2b is [MoOS3Cu3(bpy)2Cl]. The product of oxidation of [Febpy)3]Cl2 found in the course of the preparation of 2a was characterized as [Fe(bpy)3][Fe2OCl6] (1) by X-ray structure determination. The products of oxidation of copper(I) led to [Cu(bpy)2]2[MS4Cu3Cl3]·CH3CN, MW (3a), a=13.854(2), b=16.452(2), c=22.072(4) Å, β=97.06(1)°, Z=4, and MMo (3b), a=13.886(7), b=16.451(4), c=22.054(15) Å, β=96.84(5)°, Z=4, which were also characterized by X-ray structure determination.