| Sumario: | Density functional theory has been used to calculate HC and MC bond dissociation enthalpies in order to evaluate the feasibility of correlating relative MC bond enthalpies ΔH(MC) with HC bond enthalpies ΔH(HC) via computational methods. This approach has been tested against two experimental correlations: a study of (a) Rh(H)(R)(Tp′)(CNCHCMe) [R = hydrocarbyl, Tp′ = HB(3,5-dimethylpyrazolyl)3] (Wick, D. D.; Jones, W. D. Organometallics 1999, 18, 495) and (b) Ti(R)(silox)(NHSit-Bu) (silox = OSit-Bu) (Bennett, J. L.; Wolczanski, P. T. J. Am. Chem. Soc. 1997, 119, 10696). We show that the observation that MC bond enthalpies increase more rapidly with different substituents than HC bond enthalpies is reproduced by theory. Quantitative slopes of the correlation lines are reproduced within 4% of the experimental values with a B3PW91 functional and with very similar correlation coefficients. Absolute bond enthalpies are reproduced within 6% for HC bonds, and relative bond enthalpies for MC bonds are reproduced within 30 kJ mol for RhC bonds and within 19 kJ mol for TiC bonds. Values are also calculated with the BP86 functional.
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