Synthesis and electrochemistry of organometallic ethanethiolato bridged complexes of ruthenium(IV)

Reaction of the ruthenium(IV) chloro-bridged dimer {Ru(η³ : η³-C₁₀H₁₆)Cl(μ-Cl)}₂], 1, with ethanethiol (EtSH) in CH₂Cl₂ gives the bridged-cleaved adduct Ru(η³ : η³-C₁₀H₁₆)Cl₂(SHEt)], 2. Stirring of two molar equivalents of 2 in methanol with one equivalent of 1 gives the binuclear, mixed chloro/thiolato bridged compound {Ru(η³ : η³-C₁₀H₁₆)Cl} ₂(μ-SEt)], 3. The related doubly thiolato bridged complex {Ru(η³ : η³-C₁₀H₁₀)Cl(μ-SEt)}₂], 4, is formed by treatment of 1 with an excess of EtSH, or by prolonged stirring of 2 alone in methanol. Compounds 2–4 have been studied by cyclic voitammetry. Compound 2 undergoes only irreversible oxidation, whereas in the case of both 3 and 4 the observation of significant return waves is consistent with a greater stability of the primary redox products.