EVALUATION OF STRAIN IN HETEROSILIRANES - SYSTEMATICS, SURPRISES, ANDPROBLEMS

A series of different isodesmic and homodesmic reactions defining stra in energies in 3-membered rings are described and discussed. One isode smic and one homodesmic reaction are applied numerically with the purp ose of estimating strain in heterosiliranes including second-row and t hird-row heteroatoms. All molecules involved are optimized using SCF/6 -31G*, and energies are calculated using MP2/6-31G**//scF/6-31G** cal culations. The results are discussed with reference to limitations of the chosen models. (C) 1996 John Wiley & Sons, Inc.