| Popis: |
Infrared spectra in the SiH stretching region are reported for SiH 3 CH 2 Cl, SiHD 2 CH 2 Cl, SiH 3 Et, SiHD 2 Et, SiHDEtMe, SiHDEt 2 , SiHEt 3 , (SiH 3 ) 2 CH 2 , (SiHD 2 )(SiD 3 )CH 2 , SiH 3 CH=CH 2 and SiHD 2 CH=CH 2 in the gas phase, and for SiH 3 CH 2 Cl, SiH 3 Et, SiHEt 3 and SiHMe 3 in hydrocarbon solvents. The presence of several types of SiH bond in the gas phase is diagnosed in all cases except those of disilyl methane and vinyl silane. These reflect the differing β effects of halogen and methyl groups. For the alkyl silanes, νSiH = 2125.8 + 41.0 Σσ*, for selected frequencies. Changes of frequency from gas to solution, and the half-widths of bands in the latter, suggest that variation in SiH bond strength contributes to the width in the case of EtSiH 3 , and that in Et 3 SiH only one conformer exists in solution to a significant extent. Stretch—stretch interaction force constants within the silyl groups of SiH 3 CH 2 Cl and SiH 3 Et are similar to those in methyl groups. Dipole—dipole forces can account for ν as SiH 3 —ν as SiH 3 coupling in (SiH 3 ) 2 CH 2 . |
