INFRARED-SPECTRA OF CRYSTALLINE METHYLSILANES AND METHYLGERMANES

Infrared spectra of polycrystalline CH3SiH3, CH3SiD3, CH3GeH3, CD3GeH3 and CH3GeD3 have been measured at 77 K. Vibrational assignments are in agreement with previous gas-phase studies of these species. The use of isotopically isolated species in the above matrices has shown that the molecular symmetry in each case is Cs, and it is suggested that methylsilane and methylgermane are isostructural. Spectra of three of the species were, in addition, obtained in argon matrices. The antisymmetric methyl deformation mode of methylsilane is shown to be involved in Fermi resonance in the gas phase, the crystal and the matrix-isolated form. No firm assignment involving the torsional modes in these species, in the crystal, could be made. © 1979.