Tp'Rh(PMe3)(CH3)H has been synthesized as a precursor to produce the coordinatively unsaturated fragment [Tp'Rh(PMe3)], which reacts with benzene, mesitylene, 3,3-dimethyl-1-butene, 2-methoxy-2-methylpropane, 2-butyne, acetone, pentane, cyclopentane and 1,1,1-trifluoroethane in ambient environment to give only one type of activation products with almost quantitative yields. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/240nm/uploads/42619_csl1.jpg' alt='' /> All of complexes Tp'Rh(PMe3)(R)H were characterized by NMR spectroscopy and the structures of their halogenated derivatives were fully determined by NMR spectroscopy, elemental analysis and X-ray crystallography. Competitive studies show a general order of C-H activation selectivity: aromatic > olefinic > primary C-H bond. The selectivity of [Tp'Rh(PMe3)] is found to be comparable with that of [Tp'Rh(CN-neopentyl)] but greater than those of [Cp*Rh(PMe3)] and [Cp*Ir(PMe3)]. The previous kinetic technique allows the establishment of relative Rh-R bond strengths, which shows a reasonable linear correlation with the corresponding R-H bond strengths, displaying a slope of 1.63 for hydrocarbons without a-substitution and a slope of 1.18 for substrates with resonance and/or inductive effects.

Kinetic and thermodynamic selectivity of intermolecular C-H activation at [Tp′Rh(PMe3)]

244th National Meeting (2012)

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