A MODEL FOR THE HYDROGEN BOND AND PROTON TRANSFER REACTIONS

A simple extension of Platt's model for determining the force constants in diatomic hydrides is used to investigate the properties of transition states for proton transfer reactions. The model is first tested by comparing the predicted and observed changes in bond lengths and stretching and bending frequencies for [Formula: see text] systems. The quantities predicted for the transition state are the geometry and the perpendicular bending frequencies. The implications of the results with regard to the interpretation of hydrogen–deuterium kinetic isotope effects are discussed. In particular, the variations in both the isotope effect and the geometry of the transition state with changing acid or base strength are considered in detail.