MINDO/3 CONFIGURATION-INTERACTION STUDIES OF ALPHA-CLEAVAGE PROCESSES IN ORGANIC-PHOTOCHEMISTRY

The α-cleavage processes (Norrish type I) in several ketones and thiones are examined. The relative heights of the activation barriers are estimated using MINDO/3 and and configuration interaction. Results reveal certain features that are of interest in organic photochemistry. The perpendicular motion of the carbon atom of the chromophore is an important component in the reaction coordinate if the cleavage process takes place in the lowest triplet state. Selectivity of the cleavage of an α bond in a non-symmetric system is determined from the third derivative of energy with respect to the reaction coordinate at the starting point of the reaction. © 1990.