Evaluation of strain in heterosiliranes: Systematics, surprises, and problems

A series of different isodesmic and homodesmic reactions defining strain energies in 3-membered rings are described and discussed. One isodesmic and one homodesmic reaction are applied numerically with the purpose of estimating strain in heterosiliranes including second-row and third-row heteroatoms. All molecules involved are optimized using SCF/6-31G**, and energies are calculated using MP2/6-31G**//SCF/6-31G** calculations. The results are discussed with reference to limitations of the chosen models.