Correlations of pK(lg)(Me) with reduction potentials

The quantitative indices for the ability of leaving groups to depart from C atoms are pK(lg)(Me). In the cases of methyl transfers from arenesulfonates, these parameters have correlated a large number of nucleophilic data. A new scale of these parameters has been defined from methyl transfer data between phenylmethyl thioethers. The pK(lg)(Me) data from both sets of compounds correlated with both experimental E(1/2) values and E(LUMO) values from computational chemistry. These correlations support the SCM model of Shaik et al. which requires the leaving group to display some SET character in an S(N)2 transition state.