Title: Collisional activation of protonated halogeno-pyridines: different behaviour of target gases
Authors: Le, HT ×
Gerbaux, P
Flammang, R
Nguyen, Minh Tho #
Issue Date: 2000
Series Title: Chemical Physics Letters vol:323 issue:1-2 pages:71-78
Conference: date:Katholieke Univ Leuven, Dept Chem, B-3001 Louvain, Belgium; Univ Mons, Organ Chem Lab, B-7000 Mons, Belgium; Ho Chi Minh City Univ Technol, Fac Chem Engn, Ho Chi Minh City, Vietnam
Abstract: Protonated 2-Cl and 2-Br-pyridines undergo facile dehalogenation upon high energy (8 keV range) collisional activation provided the target is NO, or even better O-2, instead of He or Ar. In the low energy regime (20-30 eV range), debromination occurs more readily than dechlorination, but the peculiar behaviour of O-2 in favouring an X-loss over a HX-elimination, is no longer detected (using a MS3 instrument). B3LYP/6-31G(d) calculations on X-pyridines with X = F, Cl and Br on positions 2, 3 and 4, suggest that, if a protonated pyridine is formed in the lower-lying triplet state following strong interaction with O-2 or NO having higher spin, the loss of Cl or Pr becomes almost spontaneous (F-loss is more difficult). Proton affinity PA(pyridine) = 940 +/- 15 kJ/mol, is decreased by 5-15 kJ/mol upon halogenation. (C) 2000 Elsevier Science B.V. All rights reserved.
ISSN: 0009-2614
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Quantum Chemistry and Physical Chemistry Section
× corresponding author
# (joint) last author

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