Potential energy characteristics and energy partitioning in chemical reactions: <i>A</i> <i>b</i> <i>i</i> <i>n</i> <i>i</i> <i>t</i> <i>i</i> <i>o</i> MO study of four-centered elimination reaction CH3CH2F→CH2=CH2+HF

Abstract

The mechanism of energy disposal along the reaction pathway was discussed in relation to the characteristic features of potential energy surface. A simplified theoretical model was constructed in terms of the intrinsic reaction coordinate (IRC) and normal coordinates perpendicular to it. Ab initio MO calculations with the split-valence basis set were carried out for the four-centered elimination reaction CH3CH2F→HF+CH2CH2. The energy gradient method was used to optimize the stationary points on the potential surface and to trace IRC as well as to calculate the force constants. The origin of vibrational enhancement of HF in the reaction product was interpreted as the result of interchange of the main components of IRC in a local region where the IRC curvature is large.