Abstract
The Raman spectra of gaseous disilane and disilane‐d6 as well as the Raman and infrared spectra of their crystalline solids at 20 K have been recorded from 25 to 3500 cm−1. Two quantum torsional transitions of the SiH3 moiety were observed at 233 and 251 cm−1 in the Raman spectrum of gaseous disilane. A barrier to internal rotation of 439±10 cm−1 (1.26 kcal/mol) has been calculated based on these frequencies. The crystalline modification of disilane at 20 K was shown to belong to the monoclinic space group P21/c≡C2h5. There are two molecules per unit cell each of which sits on identical Ci sites. The results of normal coordiante analyses of H3SiSiH3, H3SiNCO, and H3SiNCS are presented and the force fields obtained for the H3Si moieties are compared.