The generation, stability, dissociation and ion/molecule chemistry of sulfinyl cations in the gas phase

Abstract

Sulfinyl cations [R-S+-O (R = CH,, Ph, Cl, CH,O and C,H,O)] have been demonstrated by MO calculations in conjunction with pentaquadrupole multidimensional (2D and 3D) MS2 and MS3 mass spectrometric experiments to be stable and easily accessible gas phase species, and their dissociation and ionlmolecule chemistry have been studied. Potential energy surface diagrams indicate that the sulfoxides (CH3)2S=O, P h , W , Cl, S==O, (CH,O),S=O and (C,H,0)2S==0 do not undergo rearrangement upon dissociative ionization, yielding the corresponding sulfinyl cations as primary fragments. Ph(CH,)S-O + ', on the other hand, is predicted to isomerize to CH,-SO -Ph+' via a four-membered ring transition state, yielding upon further CH,' loss the isomeric ion W +-P h. The sulfinyl cations were found by ab initio calculations to be much more stable than their S=O+-R isomers, hence isomerization via [ 1,2-R] shifts is not expected. Direct cleavage of the R-SO+ bonds and/or processes that are preceded by isomerization dominate the low-energy collision dissociation chemistry of the sulfinyl cations, thus providing limited structural information. On the other hand, a general and structurally diagnostic ion/molecule reaction with 2-methyl-l,3-dioxolane occurs for all the sulfinyl cations yielding abundant net oxirane (C,H,O) addition products. The reaction probably occurs via a transketalization-like mechanism that leads to cyclic 2-thia-l,3-dioxolanylium ions. This reactivity parallels that of several acylium (R<+=O) and thioacylium ions (R-Cf=S), and is not shared by the isomeric ions SO+-Ph and CH,=S+-OH. While the corresponding acylium ions react extensively with isoprene by [4 + 2'1 cycloaddition, only the phenylsulfinyl cation Ph-S+=O yields an abundant cycloadduct.

Ion/molecule reactions in a miniature RIT mass spectrometer

“…This reaction parallels the transacetalization between aldehydes/ketones with the formation of cyclic acetals in solution and is also related to the classical acetalization of aldehydes/ketones with diols. Discovered a decade ago,34 the Eberlin reaction has been extended to many other amphoteric ions having both a Lewis acidic and basic site; they include thioacylium (R–C + S),34 carbosulfonium (H 2 CS + —R),46 sulfinyl (R–S + O),47 borinium (RO) 2 B + ,48 arylnitrenium (ArNH + ),42 silylium (RO) 3 Si + 48 and phosphonium (R 2 P + O)31, 48, 49 ions.…”

Ketalization of phosphonium ions by 1,4-dioxane: Selective detection of the chemical warfare agent simulant DMMP in mixtures using ion/molecule reactions

“…For instance, these transacetalization reactions can be used to characterize functional group in either ionic or neutral reactants, revealing specific structural details or distinguishing them from isomers. The gas phase synthesis of several heterocycles has been performed via related transacetalizations with other gaseous amphoteric cations such as sulfinyl [33,34], silylium [35], and borinium [36,37] ions.…”

Locating the charge site in isomeric pyrrolyl ions by Eberlin ion/molecule reactions

“…In Eberlin reactions (Scheme 1), a variety of acylium [1][2][3] and related sulfur, 4 phosphorus and borinium ions 5 react with 1,3-dioxolane (and other cyclic acetals) to form 1,3-dioxanylium ions (Eberlin products) via formal replacement of neutral formaldehyde by the [R-C ¼ Y] þ amphoteric cations. This reaction has been shown to be very general, 3 and to occur for a variety of five-, six-and seven-membered cyclic acetals, i.e., 1,3-dioxaheterocycles and their sulfur and nitrogen analogues.…”