“…The interesting structure and properties of sulfolane (tetrahydrothiophene) and its unsaturated derivative 3-sulfolene (2,5-dihydro-thiophene) have turned the attention to investigate their ring inversion and vibrational spectra [1][2][3][4][5][6]. The structural stability of the two molecules has been the subject of rotational microwave [3,4], vibrational infrared, Raman spectroscopic techniques [1,2] and electron diffraction [5].…”