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Steric gamma effect on 29 Si shielding in (CH 3 ) 3 SiOCR groups
Author(s) -
Engelhardt G.,
Schraml J.
Publication year - 1977
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270090414
Subject(s) - steric effects , silicon , resonance (particle physics) , adamantane , chemistry , electromagnetic shielding , crystallography , stereochemistry , materials science , atomic physics , physics , organic chemistry , composite material
Abstract 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.