CONFORMATIONAL PREFERENCES IN METHYLSILANE AND DISILANE - QUANTITATIVE NON-EMPIRICAL ANALYSIS OF THE IMPORTANCE OF THE HYPERCONJUGATIVE INTERACTIONS

We have investigated the importance of the hyperconjugative interactions in determining the conformational preferences in methylsilane and disilane, and for comparative purposes also in ethane, using a procedure that provides quantitative information about the energy effects associated with orbital interactions. It is found that (1) these interactions are in all cases destabilizing and less destabilizing in the staggered conformation and that (2) in the absence of these interactions, in ethane the staggered conformer is still more stable, while in methylsilane and disilane the eclipsed conformer becomes more stable. We have also investigated the effects of each type of orbital interaction in terms of a quantitative perturbational analysis. © 1979 Springer-Verlag.