Is the tropylium ion (Tr+) formed from toluene at its thermochemical threshold?

C. Lifshitz; Y. Gotkis; A. Ioffe; J. Laskin; S. Shaik

doi:10.1016/0168-1176(93)80020-F

Is the tropylium ion (Tr⁺) formed from toluene at its thermochemical threshold?

C. Lifshitz^*, Y. Gotkis, A. Ioffe, J. Laskin, S. Shaik

^*Corresponding author for this work

Institute of Chemistry

Research output: Contribution to journal › Article › peer-review

65 Scopus citations

Abstract

The role of tropylium ion (Tr⁺) versus benzylium ion (Bz⁺) formation by H loss from toluene radical cation (TOL⁺) was studied by time-resolved photoionization mass spectrometry, by ab initio calculations and by RRKM-QET. Tr⁺ is not formed at its thermochemical threshold owing to the presence of a reverse activation energy for the reaction leading from the cycloheptatrien radical cation (CHT⁺) to Tr⁺ + H. The critical energies required to form Bz⁺ and Tr⁺ from TOL⁺ are very close, being 2.18 and 2.11 eV, respectively. The computational results are in excellent agreement with experiments regarding appearance energies, heats of formation and Tr⁺/Bz⁺ abundance ratios as a function of energy.

Original language	English
Pages (from-to)	R7-R11
Journal	International Journal of Mass Spectrometry and Ion Processes
Volume	125
Issue number	1
DOIs	https://doi.org/10.1016/0168-1176(93)80020-F
State	Published - 24 May 1993

Keywords

Ab initio calculations
Benzylium
RRKM-QET
Time-resolved photoionization mass spectrometry
Toluene
Tropylium

Access to Document

10.1016/0168-1176(93)80020-F

Cite this

@article{29493c1b2f1d429f95f7cb69cfb9a402,

title = "Is the tropylium ion (Tr+) formed from toluene at its thermochemical threshold?",

abstract = "The role of tropylium ion (Tr+) versus benzylium ion (Bz+) formation by H loss from toluene radical cation (TOL+) was studied by time-resolved photoionization mass spectrometry, by ab initio calculations and by RRKM-QET. Tr+ is not formed at its thermochemical threshold owing to the presence of a reverse activation energy for the reaction leading from the cycloheptatrien radical cation (CHT+) to Tr+ + H. The critical energies required to form Bz+ and Tr+ from TOL+ are very close, being 2.18 and 2.11 eV, respectively. The computational results are in excellent agreement with experiments regarding appearance energies, heats of formation and Tr+/Bz+ abundance ratios as a function of energy.",

keywords = "Ab initio calculations, Benzylium, RRKM-QET, Time-resolved photoionization mass spectrometry, Toluene, Tropylium",

author = "C. Lifshitz and Y. Gotkis and A. Ioffe and J. Laskin and S. Shaik",

year = "1993",

month = may,

day = "24",

doi = "10.1016/0168-1176(93)80020-F",

language = "אנגלית",

volume = "125",

pages = "R7--R11",

journal = "International Journal of Mass Spectrometry and Ion Processes",

issn = "0168-1176",