Steric gamma effect on 29 Si shielding in (CH 3 ) 3 SiOCR groups

It is shown that a γ‐methyl group causes approximately a 3 ppm upfield shift of the silicon resonance in (CH 3 ) 3 SiOCCH 3 fragments. It is estimated that polar effects contribute about 0.8 ppm to this shift leaving a net steric γ upfield shift of 2 ppm. Variations around these average values are interpreted by different conformer populations, the importance of which are illustrated by the shifts in trimethylsiloxy derivatives of adamantane.