Gibbs energies of activation for reacting systems with multiple reactant‐state and transition‐state conformations

Three distinct procedures for obtaining the effective Gibbs energies of activation from computed energies for a reaction involving multiple reactant-state (RS) and transition-state (TS) conformers are shown to be equivalent. If Boltzmann-weighted average Gibbs energies for RS and TS are evaluated, then the Gibbs energy contribution from entropy of mixing of both RS and TS conformers must also be included in order to obtain the correct value for the effective Gibbs energy of activation. Application to a solvolytic reaction of 4,4’-dimethoxybenzhydrylpyridinium cation, which is shown to satisfy the Curtin-Hammett principle with rapid interconversion of RS conformers, demonstrates the use of each procedure for evaluation of the effective Gibbs energy of activation.