Proton magnetic resonance spectra of di- and trisubstituted derivatives of methylsilane

Abstract

The proton magnetic resonance spectra of 23 di- and tri-substituted derivatives of methylsilane are reported. The α-proton chemical shifts in these compounds are generally non-additive properties of the α-substituents. The deviations from additivity are largest for highly electronegative or bulky substituents. In contrast, the β-proton chemical shifts are generally additive properties of the α-substituents, though deviations from additivity are observed for the fluorides. The factors affecting the β-proton chemical shifts are discussed. The directly bound β(C,H) and α(Si,H) and vicinal (H, H) coupling constants are approximately additive properties of the least electronegative substituents. The vicinal (H, H) coupling constants in substituted methylsilanes generally decrease with increasing substituent electronegativity. The geminal (Si, H) coupling constants are rather insensitive to change of substituent.