IR spectroscopy of protonated toluene:: Probing ring hydrogen shifts in gaseous arenium ions

被引:45
作者
Dopfer, O
Lemaire, J
Maître, P
Chiavarino, B
Crestoni, ME
Fornarini, S
机构
[1] Univ Roma La Sapienza, Dipartimento Studi Chim & Tecnol Sostanze Biologi, I-00185 Rome, Italy
[2] Univ Wurzburg, Inst Phys Chem, D-97074 Wurzburg, Germany
[3] Univ Paris 11, Chim Phys Lab, UMR8000, Fac Sci Orsay, F-91405 Orsay, France
关键词
photodissociation; FT-ICR mass spectrometry; IR spectroscopy; reactive intermediates; structure elucidation;
D O I
10.1016/j.ijms.2005.12.039
中图分类号
O64 [物理化学(理论化学)、化学物理学]; O56 [分子物理学、原子物理学];
学科分类号
070203 ; 070304 ; 081704 ; 1406 ;
摘要
Toluenium ions [CH3C6H6](+), formed by protonation of toluene by C2H5+ ions in the cell of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer, have been assayed by IR multiphoton dissociation (IRMPD) spectroscopy. Their IRMPD spectrum compares well with the calculated IR absorption spectra for the ortho-, meta-, and para-toluenium isomers, suggesting a mixture rich in the ortholpara isomers. When the protonation is effected on perdeuterated toluene, the so-formed ions present IRMPD features characteristic for both CD2 and CHD groups in the arenium ring. This finding is spectroscopic evidence for the occurrence of ring hydrogen shifts and provides the first example of differentiation of families of isotopomers (bearing either two D-atoms or one D-atom and one H-atom on the tetrahedral ring carbon) by the powerful tool of IRMPD using the tunable IR radiation of a free electron laser. (c) 2006 Elsevier B.V. All rights reserved.
引用
收藏
页码:149 / 154
页数:6
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