SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF INCOMPLETE CUBANES DERIVED FROM [MS4CU4CL4]2- (M=MO, W) ANIONS

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) angstrom, V = 4893(3) angstrom3, Z = 8, R = 0.059 and R(w) = 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][Fe,OCI,] (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) angstrom, beta = 97.06(1)-degrees, Z = 4, and M = Mo (3b), a = 13.886(7), b = 16.451(4), c = 22.054(15) angstrom, beta = 96.84(5)-degrees, Z = 4, which were also characterized by X-ray structure determination.