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

Abstract

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.

HPLC/APCI Mass Spectrometry of Saturated and Unsaturated Hydrocarbons by Using Hydrocarbon Solvents as the APCI Reagent and HPLC Mobile Phase

“…The peaks of m/z 436.50 and 437.50 correspond to isotopologues of nhentriacontane were isolated and allowed to undergo ion/molecule reactions with dimethyl disulfide in the trap. Radical cations, such as [M -2H] +• and M +• , are expected to react with dimethyl disulfide by electron abstraction (if they have a conventional structure and ionization energy greater than that of dimethyl disulfide; 8.2 eV) [33] or SCH 3 abstraction (if they have a distonic structure [34][35][36]), while even-electron ions should be unreactive. For all analytes, dimethyl disulfide radical cation was formed in the ion source, probably due to ionization of dimethyl disulfide by the radical cation of the sheath gas (N 2 ).…”

The ionized methylene transfer from the distonic radical cation +CH2-O-CH2 to heterocyclic compounds. A pentaquadrupole mass spectrometric study

“…However, the MS3 spectra of the m/z 102 product ( Figure 7a) is very different from the MS2 spectra of both the authentic ions 12 ( Figure 7b Scheme VII their conventional isomers, but sufficiently kinetically stable toward isomerization in the gas phase, appears therefore to be a general trend. Kenttlmaa and co-workers [19] also have recently shown by ab initio calculations that the distonic sulfur ion CH,S+(CH;)CH, is less stable than its conventional isomer CH,CH,SCH:; but the former is sufficiently stable in the gas phase so that its isolation and identification can be achieved.…”

Formation and characterization of the sulfur-containing distonic radical anion, , in the gas phase, in the gas phase

“…The interest m these ins arises in part from the findmg that some sunple distomc radical cations that contain a halogen, mtrogen, or oxygen atom (e.g., "CH2OH ~) are more stable than their conventional isomers (e.g., CHBOH +') [2,6]. The oppomte situation applies to simple sulfur-containing dlstomc radical cations [1,[7][8][9][10][11][12][13], which according to ab mitio calculations are less stable than the conventional isomers [1,7]. For example, the distonic radical cation CH2--SH--CH 3 is estimated to be about 80 kJ tool -1 higher in energy than the conventional CH3--S + --CH 3 ion [7] In contrast to the extensive literature concerning dlstonic radical cations, very little is known about distonic radical anions.…”