| Abstract
| - Redox reactions of [Cp*RuIII(tpdt)] (2) initiated by alkylation or oxidation led to the formation of the S−S coupled Ru(II) complexes 3 and 6, respectively, via intermediate thiyl radicals. 3 undergoes a facile reversible homolytic cleavage to generate 3A, which can be reduced to 8, behave as radical initiator toward nBu3SnH, or couple with 2 to form 7 via IET and SN2 processes.
- Alkylation of [Cp*RuIII(tpdt)] (2) (Cp* = η5-C5Me5, tpdt = η3-S(CH2CH2S-)2) with MeI orMe3OBF4 resulted in the formation of a trans μ-η1-η1-S2 coupled species, [{Cp*RuII}2{μ-η6-(S(CH2)2S(CH2)2SMe)2}]2+ (3) as the predominant product. With MeI the reaction also gavea small amount of [Cp*RuII{η3-S(CH2CH2SMe)2}]I, 4(I), but in the presence of acrylonitrile(AN), the products were 4(I) and [Cp*RuII{η3-S((CH2)2S)2(CH2CHCN)}]I, 5(I), of which thelatter was the sole product from the reaction of 2 with AN in the presence of iodine. 2 waselectrochemically easily oxidized in a one-electron process; its chemical oxidation with I2led to the isolation of [{Cp*RuII}2{μ-η6-(S(CH2CH2S)2)2}](I3)2, 6(I3)2, containing a cyclic RuII(μ-S2)2RuII core. A combination of electrochemical, EPR, UV−vis, and NMR experimentsindicated that the solution phase chemistry of 3 is governed by its facile reversible dissociationinto the mononuclear cation radical (3A). Based on this phenomenon were rationalized thepathways leading to the formation of the dinuclear species [{Cp*RuII}2{μ-η5-MeS(CH2)2S(CH2)2SS(CH2)2S(CH2)2S}]+ (7) from the interaction of 3 and 2, or of a mixture of 4(I) and5(I) in the presence of MeI and AN, and of [Cp*RuII{η3-MeS(CH2)2S(CH2)2SSnBu3}]+ (9) fromreaction with tri(n-butyl)tin hydride. Electrochemical measurements indicated that thesodium naphthalide reduction of 3 to generate the mono-S-methylated derivative, [Cp*RuII{η3-S(CH2)2S(CH2)2SMe}] (8), occurred through 3A. It is proposed that some of thetransformations also involved internal electron transfers and nucleophilic displacements.The X-ray crystal structures of the complexes 3−9 are reported.
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