Zaikin VG, Kozlov AV, Borisov RS, Shchapin IY. Regio-isomeric effects in tandem mass spectra of sulfonium cations generated from thiacyclane based sulfonium salts under soft ionization conditions.
EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2018;
24:108-115. [PMID:
29232998 DOI:
10.1177/1469066717723909]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The influence of regio-isomerism of even-electron sulfonium ions on tandem electrospray and matrix-assisted laser desorption/ionization mass spectra recorded by using collision-induced dissociation was investigated. The initial organic sulfides belonged to isomeric thiabicyclane series (substituted 7- and 8-thiabicyclo[4.3.0]nonanes, 2- and 3-thiabicyclo[4.4.0]decanes) and phenylthiolanes. To investigate by the abovementioned mass spectrometry methods, the sulfides were preliminary S-alkylated by methyl, ethyl iodides, their deuterated analogs and trialkoxonium tetrafluoroborates to form corresponding sulfonium salts. The latter salts readily gave off corresponding sulfonium cations under abovementioned desorption/ionization conditions and these cations were precursor ions in collision-induced dissociation experiments. The main quantitative and frequently qualitative differences between collision-induced dissociation spectra of isomers were manifested in mass numbers and relative intensities of the ions Alk-S+ = CHR (formal structure) that originated from the destruction of sulfur-containing ring. Corresponding peaks are particularly abundant for cations Alk-S+ = CH2 and their intensities are usually greater than for other C-substituted homologues. Qualitative difference between fragmentation features of 2- and 3-phenylthiolanium cations is that only the latter can eliminate neutral C2H4S molecule.
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