| Abstract
| - At the Ru(II) oxidation state, TpRu(PMe3)2OR (R = H or Ph) undergo even-electron acid/base transformations with weakly acidic C−H bonds. Oxidation to the Ru(III) complex [TpRu(PMe3)2OH]+ shifts the reaction proclivity toward odd-electron net hydrogen atom abstraction chemistry.
- The Ru(II) complexes TpRu(PMe3)2OR (R = H or Ph) react with excess phenylacetylene at elevatedtemperatures to produce the phenylacetylide complex TpRu(PMe3)2(C⋮CPh). Kinetic studies indicatethat the reaction of TpRu(PMe3)2OH and phenylacetylene likely proceeds through a pathway that involvesTpRu(PMe3)2OTf as a catalyst. The reaction of TpRu(PMe3)2OH with 1,4-cyclohexadiene at elevatedtemperature forms benzene and TpRu(PMe3)2H, while TpRu(PMe3)2OPh does not react with 1,4-cyclohexadiene even after 20 days at 85 °C. The paramagnetic Ru(III) complex [TpRu(PMe3)2OH][OTf]is formed upon single-electron oxidation of TpRu(PMe3)2OH with AgOTf. Reactivity studies suggestthat [TpRu(PMe3)2OH][OTf] initiates reactions, including hydrogen atom abstraction, with C−H bondsthat have bond dissociation energy < 80 kcal/mol. Experimentally, the O−H bond strength of the Ru(II)cation [TpRu(PMe3)2(OH2)][OTf] is estimated to be between 82 and 85 kcal/mol, while computationalstudies yield a BDE of 84 kcal/mol, which are in reasonable agreement with the observed reactivity of[TpRu(PMe3)2OH]+.
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