Radical-type reactivity of the methylenedimethylsulfonium ion, (CH3)2S+CH2˙

✍ Scribed by Rebecca L. Smith; Leonard J. Chyall; Krista M. Stirk; Hilkka I. Kenttämaa

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 840 KB
• Volume: 28
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210281239

✦ Synopsis

A 6 initio molecular orbital calculations at the MP2/6-31G*//6-31G* + ZPVE level of theory suggest that the ion (CH,),S+--CH,'

is 75 k J mol-' higher in energy than ionized ethyl methyl sulfide. However, this distonic ion is stable toward isomerization to the conventional structure: the two ions show distinctly different reactivity in a dual-cell Fourier transform ion cyclotron resonance mass spectrometer. Molecular orbital calculations further indicate that the charge site of the ion is on the sulfur atom whereas the odd-spin density is localized on the CH, group. The chemical properties of the ion reflect this description. The coordinatively saturated sulfonium charge site is chemically inert. This radical cation possesses unique chemical reactivity in that its reactions are associated with the radical site. Most of these reactions involve a homolytic bond cleavage in the neutral molecule, resulting in abstraction of an atom or a radical by the ion. The reaction efticiency correlates with the homolytic bond dissociation energy of the bond being broken in the neutral molecule, suggesting a simple radical abstraction mechanism for these reactions. Hence, the methylenedimethylsulfonium ion is best described as on electrophilic radical with an inert charge site.