ANALYSIS OF TORSIONAL SPECTRA OF MOLECULES WITH 2 INTERNAL C3V ROTORS .13. VIBRATIONAL ASSIGNMENTS, TORSIONAL POTENTIAL FUNCTIONS, AND GAS-PHASE THERMODYNAMIC FUNCTIONS OF ISOPROPYLAMINE-D0 AND ISOPROPYLAMINE-D2

The Raman spectra of gaseous, liquid, and solid, and infrared spectra of gaseous and solid isopropylamine-d0 and -d2 have been investigated between 4000 and 50 cm-1. Differences between the spectrum of the solid phase and that of the fluid phases have been interpreted in terms of an equilibrium between low energy s-trans and high energy gauche conformers, and a complete vibrational assignment has been proposed for the s-trans conformer. The far-infrared spectra of the gaseous compounds contained bands due to the asymmetric amino and coupled methyl torsions; the assignment of these bands was aided by observation of a number of two quantum transitions for each vibrational mode. The asymmetric potential functions were calculated which resulted in values for the enthalpy differences between conformers in the gaseous phase of 446 and 523 cal/mol for the -d0 and -d2 compounds, respectively. The methyl torsional potential function of isopropylamine-d0 was calculated which led to a value for the barrier height to internal rotation of the methyl rotors of 4.23 ± 0.06 kcal/mol. Values for the ideal gas thermodynamic functions have been calculated over a range of temperatures. © 1979 American Chemical Society.