A theoretical study on the mechanism of the cycloaddition reaction between dichloroalkylidenesilylene and ethylene

Abstract

The mechanism of the cycloaddition reaction between singlet dichloroalkylidenesilylene and ethylene has been investigated with the MP2/6-31G* and B3LYP/6-31G* methods, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. The energies of the different conformations are calculated by CCSD(T)//MP2/6-31G* and CCSD(T)//B3LYP/6-31G* methods. From the surface energy profile obtained with the CCSD(T)//MP2/6-31G* method for the cycloaddition reaction between singlet dichloroalkylidenesilylene and ethylene, it can be predicted that the dominant reaction pathway for this reaction involves the initial formation of an intermediate through a barrier-free exothermic reaction (42.4 kJ mol⁻¹); this intermediate then isomerizes to an active four-membered ring product via a transition state, a second intermediate and a second transition state, for which the energy barriers are 31.2 and 32.2 kJ mol⁻¹, respectively.