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NaBAr^F₄ (sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate) was found to catalyze reactions of (Phebox)Ir^III(acetate) (Phebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) complexes, including (i) β-H elimination of (Phebox)Ir(OAc)(n-alkyl) to give (Phebox)Ir(OAc)(H) and the microscopic reverse, alkene insertion into the Ir–H bond of (Phebox)Ir(OAc)(H), and (ii) hydrogenolysis of the Ir–alkyl bond of (Phebox)Ir(OAc)(n-alkyl) and the microscopic reverse, C–H activation by (Phebox)Ir(OAc)(H), as indicated by H/D exchange experiments. For example, β-H elimination of (Phebox)Ir(OAc)(n-octyl) (2-Oc) proceeded on a time scale of minutes at −15 °C in the presence of (0.4 mM) NaBAr^F₄ as compared with a very slow reaction at 125 °C in the absence of NaBAr^F₄. In addition to NaBAr^F₄, other Lewis acids are also effective. Density functional theory calculations capture the effect of the Na⁺ cation and indicate that …