Quantum theory of concerted proton transfer reactions in polar media. Linear electronic terms
Abstract
A quantum mechanical theory has been developed for concerted two-proton transfer reactions in polar media. The formulation is based on second order quantum mechanical perturbation theory; this assumes that the intermediate state, i.e., the state prevailing after the transfer of the first proton, is short-lived compared with the uncertainty time of the system. The energy of activation Ea of the overall process is determined by the value of Ea for either the first or the second proton transfer, and it is shown how, at least in principle, a distinction from a one-proton and a consecutive two-proton transfer reaction can be made. Important qualitative and semiquantitative correlations between energy of activation and overall energy of reaction are predicted, and the Brønsted coefficient and pre-exponential Arrhenius factor are discussed.