Vibrational Spectra of Sulphonyl Derivatives. V. A Reassignment of the SO2 Stretching Frequencies in Sulphonyl Fluorides

The symmetric SO2 stretching frequency in methane sulphonyl fluoride and a number of aromatic sulphonyl fluorides is reassigned to a frequency of 1210 cm-1 on the basis of new infra-red evidence (vapour and solution spectra of CH3SO2F and the infra-red spectra of a number of aromatic sulphonyl chlorides and the corresponding fluorides). Complete vibrational assignments for benzene sulphonyl chloride, benzene sulphonyl fluoride, and methyl benzene sulphonate are also given. The S-F stretching frequency appears as a strong infra-red band near 780 cm-1 and the aromatic sulphonyl frequency near 1090 cm-1 is identified as being more specifically characteristic of the Car-S bond.