A theoretical comparison of primary deuterium kinetic isotope effects in analogous hydride and hydron transfer processes

Abstract

The semiclassical primary deuterium kinetic isotope effect (3.30 at 298 K) for symmetrical hydride transfer from HNCH₂ to HCNH⁺, computed at the HF/3–21G level of ab initio molecular orbital (MO) theory, is smaller than that for analogous proton transfer from HNCH₂ to –HCNH (4.38) owing to extensive participation in the reaction-coordinate vibrational mode of degrees of freedom other than asymmetric C ⋯ H stretching.