ANALYSIS OF TORSIONAL SPECTRA OF MOLECULES WITH 2 INTERNAL C3V ROTORS .17. TORSIONAL POTENTIAL FUNCTION FOR ISOPROPYLCHLORIDE

To demonstrate the utility of the Raman effect in determining the torsional potential function and the coupling parameters, the Raman spectrum of isopropylchloride was recorded between 50 and 520 cm-1 with a resolution of 2 cm-1. The far infrared spectrum was recorded over the same frequency range with a resolution of 0.5 cm-1. Considerable torsional data are reported and used to characterize the torsional potential function based on a semi-rigid model. The average effective V3 was found to be 1380 ± 3 cm-1 (3.95 ± 0.01 kcal/mole). The cosine-cosine coupling term V33 was found to be 209 ± 12 cm-1 (0.60 ± 0.03 kcal/mole) and the sine-sine coupling term V′33 has a value of -17 ± 2 cm-1 (-0.05 ± 0.01 kcal/mole). These data are compared with the corresponding quantities obtained from microwave data and torsional studies on the solid phase. The effects on the barrier by the addition of chlorine atoms or methyl groups on one end of ethane are discussed. © 1979.