INTERNAL TORSIONAL VIBRATIONS AND LOW FREQUENCY EXTERNAL VIBRATIONS OF SOME ``GLOBULAR'' MOLECULES.
Loading...
Date
1969
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The far infrared and Raman spectra of solid $(CH_{3})_{3}CCl$, $(CD_{2})_{3}CCl$, $(CH_{3})_{3}CBr$, $(CH_{3})_{4}C$, $(CD_{3})_{4}C$, $(CH_{4})_{4}Si$, $CH_{3}CCl_{3}$, and $CD_{3}CCl_{3}$ have been obtained over a wide range of temperatures. For all of these compounds torsional vibrations were observed and from the frequencies, barriers to internal rotation of the methyl groups were calculated. Tertiary butyl chloride, the ``$d_{9}$'' compound and tertiary butyl bromide have barriers of 4.51, 4.82, and 3.90 kcal/mole, respectively. Values of 4.30 kcal/mole for neopentane (4.50 for the ``$d_{12}$'' compound) and 2.0 kcal/mole for tetramethylsilane were calculated. The 5.46 kcal/mole barrier calculated for methylchloroform (5.38 for the ``$d_{3}$'' compound) agrees well with the 5.8 kcal/mole obtained from inelastic neutron scattering results but is in sharp disagreement with the 2.7 kcal/mole from thermodynamic studies. Intermolecular fundamentals were observed for all compounds except the $T_{d}$ molecules and assignment to translational or librational modes will be presented.
Description
Author Institution: Department of Chemistry, University of South Carolina