Intrinsic Barriers in Nucleophilic Displacements

Article abstract of DOI:10.1021/ja00539a003

Measured rate constants and RRKM theory have been used to estimate central barrier heights in the double-minimum potential surfaces for several gas-phase S_N2 reactions.It is proposed that the barrier heights may be interpreted using the rate-equilibrium relationship originally developed by Marcus, and that the concept of intrinsic barriers embodied in this formalism can be useful when applied to nucleophilic displacements.The results are used to interpret alkoxide and fluoride nucleophilicities and leaving-group abilities.