Raman spectra of some complexes containing methyldihalo- and dimethylhalo-sulphonium cations: Isomerism in the dimethyl sulphide–bromine complex

✍ Scribed by Herbert F. Askew; Peter N. Gates; Alan S. Muir

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 756 KB
• Volume: 22
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/jrs.1250220506

✦ Synopsis

Abstract

Vibrational assignments for the skeletal modes of some complexes containing CH~3~SX~2~^+^ and (CH~3~)~2~SX^+^ (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 CH~3~SX~3~ and (CH~3~)~2~SX~2~ compounds are discussed; two isomers of (CH~3~)~2~SBr~2~ were obtained under varying reaction conditions and assigned as ionic [(CH~3~)~2~SBr^+^Br^−^] and charge‐transfer [(CH~3~)~2~S → Br~2~] 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 (CH~3~)~2~SBr^+^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.