1-Isopropyl-3-methyl-3-phenyl-1, 3-azasilinane 1 and 1-isopropyl-3, 3-dimethyl-1, 3- azasilinane 2 were synthesized and a detailed analysis of their NMR spectra, conformational equilibria and ring inversion processes is presented. Low temperature 1H/13C NMR spectroscopy, iteration of the 1H NMR spectra and quantum chemical calculations showed slight predominance of the PheqMeax over the PhaxMeeq conformer ...