The Infrared Spectra of Propane and Its Symmetrical Deuterium Substituted Analogs

The infrared spectra of 2,2-dideuteropropane, 1,1,1,3,3,3-hexadeuteropropane, and octadeuteropropane are presented, together with that of propane for comparison. Complete assignments are proposed for the frequencies of the vibrations belonging to species A1 and B1, and partial assignments for the vibrations belonging to species B2, in these molecules. They show that some low frequency vibrations (below 1350 cm−1) in the deuterium substituted molecules cannot be described adequately in terms of simple group motions. The results suggest that this is true also for the corresponding vibrations in propane.