Collect. Czech. Chem. Commun. 1985, 50, 1283-1290

Quantum-chemical study of photochemical E-Z isomerization of methanimine and its fluoro derivatives

Peter Ertl and Jaroslav Leška

Department of Organic Chemistry, Comenius University, 842 15 Bratislava


The CNDO/2 CI method has been used for full optimization of geometry of methanimine and its fluoro derivatives in the first excited singlet state (S1). The reaction paths of the photochemical E-Z isomerization of these molecules in the S1 state by inversion and rotation mechanisms have been studied by the method of reaction coordinate with full optimization of all other coordinates. Each of the two mechanisms mentioned goes through an energy minimum, the rotation minimum being deeper. The non-radiative transition from the rotation minimum in the S1 state to the corresponding Franck-Condon ground state enables the isomerization of the molecule. The reaction paths obtained are similar to, and the energy differences of the corresponding Franck-Condon states are close to or identical with results of the model ab initio calculations published by other authors.