ChemInform Abstract: MICROWAVE, RAMAN, AND FAR INFRARED SPECTRA, BARRIER TO INTERNAL ROTATION, AND DIPOLE MOMENT OF 2,2‐DIFLUOROPROPANE

Abstract

The microwave spectrum of 2,2‐difluoropropane has been investigated in the region from 26.5 to 40.0 GHz. Only b‐type transitions were observed and these were assigned on the basis of the rigid rotor model. The rotational constants in the ground vibrational state were found to be A = 5149.79±0.04, B = 4840.11±0.02, and C = 4805.62±0.02 MHz. Two excited states were also identified and assigned as the excited states of the two methyl torsional modes. From relative intensity measurements the frequencies for these two methyl torsional modes were determined to be ν(A2) = 217±15 and ν(B2) = 250±30 cm−1. From the Stark effect the dipole moment was determined to be ‖μb‖ = ‖μt‖ = 2.40±0.02 D. No splitting due to the internal rotations of the methyl groups were observed in the ground or first excited states. From a diagnostic least‐squares adjustment to fit the three rotational constants, the following heavy atom structural parameters were obtained: r(C–F) = 1.352±0.013 A; r(C–C) = 1.532±0.013 A; ∢FCF = 106.09±1.44°...