Trends in R-X Bond Dissociation Energies (R• = Me, Et, i-Pr, t-Bu, X• = H, Me, Cl, OH)

Trends for R X bond dissociation energies have been examined with density functional methods of B3LYP, BMK, M06-2X, MC3MPW, B2PLYP, MCG3-MPW, and XYG3, as well as 03, MCG3/3, G3X, and 04 theories as functions of alkylation (i.e., IT = Me, Et, i-Pr, (-Bu) and X' substitution (i.e., X' = H, Me, Cl, OH). The results highlight the physical origin of success or failure of each method and demonstrate the good agreement with experimental results for G4, MCG3-MPW, and XYG3. The last holds great promise as a reliable method that is applicable to larger systems.