The Insertion of Singlet Silylene into Ethylene

Ab initio calculations at the minimal, split valence and extended basis set levels, both with and without electron correlation corrections, were used to study the insertion of singlet silylene into ethylene to form silacyclopropane. The least motion C2v path is symmetry forbidden and an artificial barrier of about 36 kcal/mol is found within C2v symmetry. Relaxation of symmetry to C, eliminates the symmetry forbiddenness of the reaction. The 3‐21G and 6‐31G* SCF calculations still predict a small barrier along this symmetry allowed path; however, the addition of second order correlation corrections results in the prediction of an insertion process with no barrier. The overall ΔE for the reaction is predicted by MP2/6‐31G*//3‐21G to be 47.9 kcal/mol.