The kinetic deuterium isotope effect of proton‐transfer reactions in solution. Comparison of the marcus and the quantum‐statistical mechanical models

The free energy dependence of the kinetic deuterium isotope effect of proton‐transfer reactions in solution is usually analysed in terms of the Marcus model. By means of modern computer techniques, the more general quantumstatistical mechanical model is also amenable to routine application. The differnces in the basic assumptions of the two approaches concerning the kinetic isotope effect are discussed. Reaction series for which both the Brønsted relation and the free‐energy dependence of the kinetic isotope effect are available are analysed by means of the two models using one set of parameters for both free‐energy relations.