Carbon and secondary deuterium kinetic isotope effects on SN2 methyl transfer reactions

Carbon and secondary deuterium kinetic isotope effect (KIE) for three types Of S(N)2 methyl transfer reactions have been predicted theoretically at a DFT level in gas phase and in aqueous solution modelled by the PCM continuum solvent model. No correlation between these isotope effects and geometrical features of the corresponding transition states (TSs), force constants of the imaginary frequency or Gibbs free energies of the studied reactions has been found. These findings suggest that comparative analysis of the magnitudes of the studied KlEs should be constrained to interpretation of the TS localization on the reaction coordinate only in a series of very closely related reactions. Copyright (c) 2007 John Wiley & Sons, Ltd.