Gas-phase bimolecular reactions between ·CH2–(CH2)n–C+=O distonic ions and pyridine: a combined experimental and theoretical study

Eur. J. Mass Spectrom. 9, 305–318 (2003)
DOI: 10.1255/ejms.551

Gas-phase bimolecular reactions between ^·CH₂–(CH₂)_n–C⁺=O distonic ions and pyridine: a combined experimental and theoretical study

Pascal Gerbaux,^* Pascale Wantier, Micheline Bury, Claude De Meyer, Daniel Finet and Yves Van Haverbeke
Organic Chemistry Laboratory, University of Mons-Hainaut, 19 Avenue Maistriau, B-7000 Mons, Belgium. E-mail: Pascal.Gerbaux@umh.ac.be

ABSTRACT:

The gas-phase reactivities of the well- known ^·CH₂CH₂C⁺=O and ^·CH₂CH₂CH₂C⁺=O distonic ions towards neutral pyridine were studied both experimentally (six sector hybrid mass spectrometer) and theoretically (density functional theory and Møller–Plesset ab initio calculations). Competitively to the charge exchange and protonation processes, both radical cations react with pyridine by an initial bonding between the positive charge site of the ion and the lone electron pair of the neutral molecule. At variance with previously reported studies in which such a nucleophilic interaction was proposed to play only a transient catalytic role, the initial C–N bond is likely to remain in the observed ion–molecule reaction products. The structures of the ion–molecule reactions products were probed by collisional activation at high kinetic energy and the reaction pathways were tentatively proposed on the basis of labeling experiments and ab initio molecular orbital calculations.

Keywords: distonic ions, pyridine, ion–molecule reactions, quantum calculations, mass spectrometry, collisional activation

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