Conformational analysis of three simple organosilicon compounds

The 1H NMR spectra of 3-(triethoxysilyl)propanenitrile (1), 3-(trichlorosilyl)propanenitrile (2) and trichloropropylsilane (3) show that these systems are present to about 40% in the gauche conformer. For 1 and 3, the solvent dependence of the conformational equilibrium has also been studied. In more polar solvents, the more polar gauche conformers contribute to a greater extent to the equilibrium mixture. The results of MNDO calculations for these compounds are compared with the conclusions drawn from the NMRz measurements. The reliability of MNDO for the description of this type of organosilicon compound is described.