Transition-state structure and the temperature dependence of the kinetic isotope effect

The underlying theory of the temperature dependence of the kinetic hydrogen isotope effect (KIE) is presented herein. The implications of this technique as a mechanistic criterion are pointed out in a straightforward manner. Some model calculations referring to the intramolecular proton transfer in the monoprotonated methylenediamine are included. The results of this investigation indicated that the temperature dependence of the KIE should not be used as a mechanistic tool in differentiating between linear and bent transition states