1H NMR Study of some Substituted Acyclic Silaethanes, 2-Silapropanes and 2-Methyl-2-Silapropanes and their Rotameric Populations around the Si-C Bond

Article abstract of DOI:10.1002/mrc.1270130406

Three series of substituted silaalkanes, (i) SiH3CH2X, (ii) MeSiH2CH2X and (iii) Me2SiHCH2X, have been prepared (X=Cl, Br, I, NMe2, OMe, SMe), and the shifts and coupling constants extracted from their 1H NMR spectra.Coefficients averaged over three rotameric states can be obtained from the first series which are used for the correction of coupling constants resulting from the presence of the electronegative substituents X.With the aid of the Karplus-Conroy angular dependence of the interproton coupling constants in silaethane fragments, corrected for electronegative substitution, approximate rotameric population in series ii and iii were obtained.Except for X=NMe2, there is always a preference for a synclinal X/CH3 relationship, even for sandwiched situation (series iii).