Octahedral Ru(II) amido complexes TpRu(L)(L')(NHR) (Tp = hydridotris(pyrazolyl)borate; L = L' = P(OMe)3 or PMe3 or L = CO and L' = PPh3; R = H,Ph, or tBu): synthesis,characterization, and reactions with weakly acidic C-H bonds

The octahedral Ru(II) amine complexes TpRu(L)(L')(NH(2)R)]OTf] (L = L' = PMe(3), P(OMe)(3) or L = CO and L' = PPh(3); R = H or (t)Bu) have been synthesized and characterized. Deprotonation of the amine complexes TpRu(L)(L')(NH(3))]OTf] or TpRu(PMe(3))(2)(NH(2)(t)Bu)]OTf] yields the Ru(II) amido complexes TpRu(L)(L')(NH(2)) and TpRu(PMe(3))(2)(NH(t)Bu). Reactions of the parent amido complexes or TpRu(PMe(3))(2)(NH(t)Bu) with phenylacetylene at room temperature result in immediate deprotonation to form ruthenium-amine/phenylacetylide ion pairs, and heating a benzene solution of the TpRu(PMe(3))(2)(NH(2)(t)Bu)]PhC(2)] ion pair results in the formation of the Ru(II) phenylacetylide complex TpRu(PMe(3))(2)(Ctriple bond]CPh) in >90% yield. The observation that TpRu(PMe(3))(2)(NH(2)(t)Bu)]PhC(2)] converts to the Ru(II) acetylide with good yield while heating the ion pairs TpRu(L)(L')(NH(3))]PhC(2)] yields multiple products is attributed to reluctant dissociation of ammonia compared with the (t)butylamine ligand (i.e., different rates for acetylide/amine exchange). These results are consistent with ligand exchange reactions of Ru(II) amine complexes TpRu(PMe(3))(2)(NH(2)R)]OTf] (R = H or (t)Bu) with acetonitrile. The previously reported phenyl amido complexes TpRuL(2)(NHPh) L = PMe(3) or P(OMe)(3)] react with 10 equiv of phenylacetylene at elevated temperature to produce Ru(II) acetylide complexes TpRuL(2)(Ctriple bond]CPh) in quantitative yields. Kinetic studies indicate that the reaction of TpRu(PMe(3))(2)(NHPh) with phenylacetylene occurs via a pathway that involves TpRu(PMe(3))(2)(OTf) or TpRu(PMe(3))(2)(NH(2)Ph)]OTf] as catalyst. Reactions of 1,4-cyclohexadiene with the Ru(II) amido complexes TpRu(L)(L')(NH(2)) (L = L' = PMe(3) or L = CO and L' = PPh(3)) or TpRu(PMe(3))(2)(NH(t)Bu) at elevated temperatures result in the formation of benzene and Ru hydride complexes. TpRu(PMe(3))(2)(H), Tp(PMe(3))(2)Rudouble bond]Cdouble bond]C(H)Ph]OTf], Tp(PMe(3))(2)Ru=C(CH(2)Ph)N(H)Ph]]OTf], and TpRu(PMe(3))(3)]OTf] have been independently prepared and characterized. Results from solid-state X-ray diffraction studies of the complexes TpRu(CO)(PPh(3))(NH(3))]OTf], TpRu(PMe(3))(2)(NH(3))]OTf], and TpRu(CO)(PPh(3))(Ctriple bond]CPh) are reported.