Quantum Mechanically Based Rules for Thermal and Photochemical Reactions

Abstract

There are at least three approaches necessary for the application of quantum mechanical considerations to the analysis of the mechanisms of thermal and photochemical reactions. These approaches are: i) generalized rules for correlating the electronic states of the starting materials and the products; ii) direct computational estimates of the potential energy surfaces and other properties of the systems under consideration, and iii) qualitative rules by which the possible shapes of the potential energy surfaces can be predicted or the possible course of the reactions can be rationalized. Approaches i and iii provide a theoretical base for building the necessary qualitative understanding of thermal and photochemical reactions and ii provides a route for partially testing that understanding. Since there is no comprehensive discussion of all these factors in the literature this paper will attempt to correlate these approaches with what has been found to date. No attempt is made, however, to give a complete review of the literature on this subject. Particular emphasis has been given to the recent literature.