Computational and dynamic NMR investigation of 2,2‐dimesityl‐1,1,1,3,3,3‐hexamethyltrisilane

The structure and rotational barrier for the mesityl‐silicon bond of 2,2‐dimesityl‐1,1,1,3,3,3‐hexamethyltrisilane have been investigated by 1 H‐ and 13 C‐variable temperature nuclear magnetic resonance (NMR) as well as by density functional theory structural calculations. The calculations show that the lowest energy structure has C 2 symmetry with nonequivalent ortho methyl groups, consistent with the crystal structure and solution NMR. The nonequivalent ortho methyl groups exchange through a C s transition state with a calculated relative free energy of 11.0 kcal mol −1 . The barrier for this rotation found by dynamic NMR is 13.4 ± 0.2 kcal mol −1 at 298 K.