THE RAMAN SPECTRA OF LIQUID SULPHUR TRIOXIDE AND SOLUTIONS OF SULPHUR TRIOXIDE IN INERT SOLVENTS

The Raman spectra of liquid sulphur trioxide and of sulphur trioxide dissolved in a number of "inert" solvents have been investigated. A detailed analysis of the spectrum of liquid sulphur trioxide supports the earlier suggestion of Gerding and Nijveld that the main polymeric species in liquid sulphur trioxide is the cyclic trimer. Frequencies are assigned for all the Raman active vibrations of the cyclic trimer. These assignments differ substantially from those given previously by Gerding and Nijveld.The spectra of dilute solutions of sulphur trioxide in sulphur dioxide, sulphuryl chloride, carbon tetrachloride, tetrachlorethylene, and trichlorfluormethane (Freon 11) show that the sulphur trioxide is present mainly in the monomeric form at low concentrations while at higher concentrations a polymeric form, which is very probably the trimer, is also present.