RAMAN-SPECTRA OF SOME COMPLEXES CONTAINING METHYLDIHALO-SULFONIUM AND DIMETHYLHALO-SULFONIUM CATIONS - ISOMERISM IN THE DIMETHYL SULFIDE BROMINE COMPLEX

Vibrational assignments for the skeletal modes of some complexes containing CH3SX2+ and (CH3)2SX+ (X = Cl, Br) have been made on the basis of their solid-state Raman spectra and compared with any previous data. The stabilities of the parent CH3SX3 and (CH3)2SX2 compounds are discussed; two isomers of (CH3)2SBr2 were obtained under varying reaction conditions and assigned as ionic [(CH3)2SBr+Br-] and charge-transfer [(CH3)2S --> Br2] forms. The transition of the ionic (metastable) form to the more stable charge-transfer form was monitored by differential scanning calorimetry. High-frequency shifts occur in some fundamental modes of (CH3)2SBr+Br- when Br- is replaced with a polyatomic anion, analogous to those seen in halophosphonium complexes; this is rationalized in terms of anion-cation interaction.