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An unusual intramolecular transfer of the fluorobenzyl cation between two remote amidic nitrogen atoms induced by collision in the gas phase
Author(s) -
Yan Zhengyin,
Tounge Brett,
Caldwell Gary W.
Publication year - 2011
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.5297
Subject(s) - chemistry , intramolecular force , protonation , ionic bonding , dissociation (chemistry) , fragmentation (computing) , ion , collision induced dissociation , photochemistry , amide , crystallography , mass spectrometry , stereochemistry , tandem mass spectrometry , organic chemistry , chromatography , computer science , operating system
A highly unusual rearrangement in collision‐induced dissociation mass spectrometry is reported that involves intramolecular transfer of the fluorobenzyl cation between two remote amidic nitrogen atoms separated by five chemical bonds. The same intramolecular transfer was also observed for two related analogs. It is postulated that the ionic reactions are initiated by protonation of the first amidic nitrogen, resulting in formation of the fluorobenzyl cation and a neutral partner that are maintained together in the gas phase by electrostatic interactions as an intermediate ion‐neutral complex. In the ion‐neutral complex, the nascent fluorobenzyl cation approaches geometrically to the second amidic nitrogen atom on the neutral partner, and subsequently forms a new C–N bond and an isomeric precursor ion as the charge is retained on the amidic nitrogen. The newly formed isomeric precursor ion eventually undergoes the final fragmentation by amide bond cleavage. Alternatively, the ionic reactions proceed through a direct intramolecular transfer mechanism by which the molecular ion adopts to a ring‐like configuration in the gas phase, so that both the donor and recipient nitrogens are geometrically close to each other within a bonding distance to permit a direct transfer between two sites even though they are separated by multiple chemical bonds. Copyright © 2011 John Wiley & Sons, Ltd.