The addition of 1Δ g oxygen molecule and ethene to give dioxetane: An MCSCF study and characterization of some previously proposed pathways

Abstract

A preliminary survey of the energy hypersurface for the addition reaction of the singlet oxygen molecule and ethene to give dioxetane has been performed at the MC-SCF level of theory using an active space of six orbitals and a minimal basis set. Four modes of approach have been studied by complete optimization of the geometries followed by diagonalization of the Hessian matrices to characterize the critical points as transition states or higher-order saddle points. None of the approaches examined ( supra-supra, supra-antara, syn diradicaloid and peroxirane-like) corresponds to a true transition state: there is a strong indication that the only path left to the system is diradical in nature, presumably in correspondence of a gauche geometry of approach.