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Ionization energies of three resonance-stabilized radicals: Cyclohexadienyl (dn, n = 0, 1, 6, 7), 1-phenylpropargyl, and methylcyclohexadienyl

Version 2 2024-06-05, 06:07
Version 1 2019-11-18, 14:48
journal contribution
posted on 2024-06-05, 06:07 authored by O Krechkivska, C Wilcox, Gerard O'ConnorGerard O'Connor, K Nauta, SH Kable, TW Schmidt
© 2014 American Chemical Society. The ionization energies for three resonance-stabilized radicals are determined: cyclohexadienyl, 1-phenylpropargyl, and methylcyclohexadienyl. The recommended ionization energies are, respectively, 6.820(1), 6.585(1), and 7.232(1) eV. That of cyclohexadienyl is found to be just 0.02 eV above a high level ab initio calculation [Bargholz, A.; Oswald, R.; Botschwina, P. J. Chem. Phys. 2013, 138, 014307], and that of 1-phenylpropargyl is found within the stated error of a recent experimental determination [Holzmeier, F.; Lang, M.; Hemberger, P.; Fischer, I. ChemPhysChem 2014, DOI: 10.1002/cphc.201402446]. The ionization energy of the methylcyclohexadienyl radical is consistent with the ortho isomer. Ionization energies of a range of isotopologues of cyclohexadienyl radical are given, along with their D1 ← D0 origin band positions, which indicate a blue shift of 18 cm-1 per deuterium atom substituted. The ionization energy of cyclohexadienyl, along with the calculated bond dissociation energy of Bargholz et al., affords a new estimate of the 0 K proton affinity of benzene: 739.7 ± 2.0 kJ/mol. The ionization energies are discussed in terms of the interplay between radical and cation stabilization energies. (Figure Presented).

History

Journal

Journal of Physical Chemistry A

Volume

118

Pagination

10252-10258

Location

Washington, D.C.

ISSN

1089-5639

eISSN

1520-5215

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Issue

44

Publisher

ACS Publications