Selective Two-Step Oxidation of μ2-S Ligands in Trigonal Prismatic Unit {Re3(μ6-C)(μ2-S)3Re3} of the Bioctahedral Cluster Anion [Re12CS17(CN)6]6–

An oxidation of cluster anion [Re12CS17(CN)6]6– by H2O2 in water has been investigated. It was shown that selective two-step oxidation of bridging μ2-S-ligands in trigonal prismatic unit {Re3(μ6-C)­(μ2-S)3Re3} takes place. The first stage runs rapidly, whereas the speed of the second stage depends on intensity of ultraviolet irradiation of the reaction mixture. Each stage of the reaction is accompanied by a change in the solution’s color. In the first stage of the oxidation, the cluster anion [Re12CS14(SO2)3(CN)6]6– is produced, in which all bridging S-ligands are turned into bridging SO2-ligands. The second stage of the oxidation leads to formation of the anion [Re12CS14(SO2)2(SO3)­(CN)6]6–, in which one of the SO2-ligands underwent further oxidation forming the bridging SO3-ligand. Seven compounds containing these anions were synthesized and characterized by a set of different methods, elemental analyses, IR and UV/vis spectroscopy, and quantum-chemical calculations. Structures of some compounds based on similar cluster anions, [Cu­(NH3)5]3[Re12CS14(SO2)3(CN)6]·9.5H2O, [Ni­(NH3)6]3[Re12CS14(SO2)3(CN)6]·4H2O, and [Cu­(NH3)5]2.6[Re12CS14(SO2)3(CN)6]0.6[{Re12CS14(SO2)2(SO3)­(CN)5(μ-CN)}­{Cu­(NH3)4}]0.4·5H2O, were investigated by X-ray analysis of single crystals.