Ab initio studies on the mechanism of dimerization reactions of ketene imine and bis(trifluoromethyl)ketene imine

The dimerization reactions of ketene imine and bis(trifluoromethyl)ketene i mine were studied theoretically. All the dimerization processes take place in a concerted but asynchronous manner, each proceeding through a four-memb ered ring transition state. For the ketene imine dimerization reactions, th ree different processes have almost equal activation barriers, while for th e three bis(trifluoromethyl)ketene imine dimerization processes the reactio n giving symmetrical a four-membered heterocyclic product has the lowest ac tivation barrier.