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.本研究针对水溶液中过氧化氢（H₂O₂）氧化簇阴离子（cluster anion）[Re₁₂CS₁₇(CN)₆]⁶⁻的反应开展了系统探究。实验证实，该反应可对三角棱柱结构单元{Re₃(μ₆-C)­(μ₂-S)₃Re₃}内的桥联μ₂-硫配体（bridging μ₂-S-ligands）实现选择性两步氧化。第一步反应速率较快，而第二步反应的速率则取决于反应体系的紫外照射强度。反应的每一步均伴随溶液颜色的变化。在氧化反应的第一步中，生成簇阴离子[Re₁₂CS₁₄(SO₂)₃(CN)₆]⁶⁻，该产物中所有桥联硫配体均转化为桥联SO₂-配体。氧化反应的第二步则生成阴离子[Re₁₂CS₁₄(SO₂)₂(SO₃)­(CN)₆]⁶⁻，该产物中有一个SO₂-配体进一步被氧化为桥联SO₃-配体。本研究通过多种表征手段——包括元素分析、红外光谱（IR）、紫外-可见光谱（UV/vis spectroscopy）以及量子化学计算（quantum-chemical calculations）——对合成得到的7种含上述簇阴离子的化合物进行了表征。此外，本研究还通过单晶X射线衍射分析（X-ray analysis of single crystals），对基于同类簇阴离子的三种化合物的晶体结构进行了解析，这三种化合物分别为[Cu(NH₃)₅]₃[Re₁₂CS₁₄(SO₂)₃(CN)₆]·9.5H₂O、[Ni(NH₃)₆]₃[Re₁₂CS₁₄(SO₂)₃(CN)₆]·4H₂O以及[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。