NEGATIVE ION PHOTOELECTRON SPECTRA OF DIHALOCARBENES AND DIHALOMETHYL RADICALS
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Date
2008
Authors
Wren, Scott
Vogelhuber, Kristen M.
Lineberger, W. Carl
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Dihalocarbenes of the form CX$_2$ (X = F, Cl, Br, I) are important intermediates in organic reactions, due to the unique chemical properties of their low-lying neutral singlet $^1$A$_1$ and triplet $^3$B$_1$ states that affect their reactivities. Disagreement between experimental and theoretical results for the singlet-triplet splittings in CCl$_2$$^-$, CBr$_2$$^-$, and CI$_2$$^-$ prompted a careful reinvestigation of the photoelectron spectra of these compounds, revealing contamination from HCX$_2$$^-$ species. Contributions from contaminants previously obscuring the dihalocarbene $^3$B$_1$ triplet spectra have been minimized, and photoelectron spectra of isolated HCX$_2$$^-$ compounds were collected to further elucidate the dihalocarbene experimental data. The new CCl$_2$$^-$ 351 nm photoelectron spectra exhibit vibrationally resolved transitions to singlet and triplet electronic states; careful analysis drastically alters the previous identification of the triplet state origin, resulting in substantially improved agreement with high level calculations.
Description
Author Institution: JILA, University of Colorado and National Institute of; Standards and Technology, and Department of Chemistry and; Biochemistry, University of Colorado, Boulder, Colorado 80309