Study on photochemistry of concerted [1, j] and [ i, j] sigmatropic rearrangements by the classical path method

Abstract

In this article, a simple and generalized method is developed for investigating nonadiabatic transitions in photochemical sigmatropic rearrangements. To achieve a rapid computation for concerted sigmatropic rearrangements, the many-body treatment developed by Matsen and the Landau-Zener model have been employed to construct the potential energy surfaces for the reaction systems, and to process the nonadiabatic transition probabilities. The nonadiabatic coupling term is evaluated by neglecting the atomic orbital deformation with respect to the reaction coordinate, thus enabling the calculation of coupling terms to be carried out with the topology of the reaction system. It can be seen from the calculations of the nonadiabatic transition for [1,3], [1,4], [1,5], and [3,3] sigmatropic rearrangements that this treatment gives more detailed information than that from the Woodward-Hoffmann rule and the usual molecular theories. The ratio lnP(H) lnP(M) (H = Hückel, M = Mobius) predicts the stereoselectivity of photochemical [ i, j] sigmatropic rearrangements including cations, radicals and neutral molecules.