Accession Number:

ADA495370

Title:

Thermochemistry and Dynamics of Reactive Species: Nitrogen-Rich Substituted Heterocycles and Anionic Components of Ionic Liquids

Descriptive Note:

Final progress rept. 1 Dec 2005-30 Nov 2008

Corporate Author:

COLORADO UNIV AT BOULDER DEPT OF CHEMISTRY

Report Date:

2009-02-01

Pagination or Media Count:

17.0

Abstract:

Investigations of the electron affinities of pyrazolyl, imidazolyl and triazoly radicals gave quantitative measurements of N-H bond strengths at the most acidic site, and provide the first detailed view of the low lying electronic excited states of the corresponding radicals. Importantly, very extensive vibronic coupling effects were observed, arising from lone pairs on adjacent nitrogen atoms. In collaboration with Professor John Stanton of the University of Texas at Austin, state-of-the-art three-state vibronic coupling calculations were performed to understand the photoelectron spectrum of pyrazolide anion. The photoelectron spectrum of 1,2,3-triazolide anion was even more complex as a result of extensive vibronic coupling, and further development of computational capability will be required before quantitative calculations are possible. Qualitative three-state calculations were in much better agreement with experiment than those that ignore vibronic coupling, but more remains to be done. In the process of these studies, it became clear that deprotonation of azoles also occurs at sites other than the most acidic sites and that ring-opened products may be formed.

Subject Categories:

  • Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE