Issue 18, 1998

Photoelectron spectrum of [14]annulene

Abstract

The He I photoelectron (PE) spectrum of [14]annulene has been measured and interpreted. UHF-MINDO/3 and UHF-MNDO computations of different molecular structures, characterized by the same π-perimeter (43 perimeter) but differing with respect to their π-bond situations (delocalized or localized) and by the geometry (different distortions imposed on the 43 perimeter in order to accommodate the four protons pointing inside), allowed us to select the energetically most favourable ones (bond delocalized D2-, C2h-, Ci- and Cs structures). The different distortions imposed upon the 43 perimeter in order to accommodate the four protons pointing inside the ring did not dramatically affect their energies. This result is supported by recent abinitio calculations, including electron correlation energy, which favoured a bond delocalized Cs structure. The interpretation of the He I PE spectrum is accomplished by comparing the observed vertical ionization energies with CNDO/S-CI computed energies of the states of the radical cations computed for the different molecular structures. This comparison confirmed that [14]annulene has its π bonds delocalized in accordance with what was deduced from dynamic studies (NMR at different temperatures) and X-ray data. The assignment of the different ionization energies to the relevant states is further substantiated by a correlation of the four first observed ionization energies of [14]annulene with those measured (and assigned by computation) for 15,16-dimethyl-15,16-dihydropyrene and pyrene.

Article information

Article type
Paper

J. Chem. Soc., Faraday Trans., 1998,94, 2695-2699

Photoelectron spectrum of [14]annulene

H. Baumann and J. Bünzli, J. Chem. Soc., Faraday Trans., 1998, 94, 2695 DOI: 10.1039/A802459F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements