US EPA

7420473 

Journal Article 

Vibrational Predissociation Spectrum of the Carbamate Radical Anion, C5H5N-CO2-, Generated by Reaction of Pyridine with (CO2)(m)(-) 

Kamrath, MZ; Relph, RA; Johnson, MA 

2010 

Yes 

Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 

AMER CHEMICAL SOC 

WASHINGTON 

132 

44 

15508-15511 

English 

20958066 

10.1021/ja1073036 

WOS:000283955600017 

https://pubs.acs.org/doi/10.1021/ja1073036
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We report the vibrational predissociation spectrum of C(5)H(5)N-CO(2)(-), a radical anion which is closely related to the key intermediates postulated to control activation of CO(2) in photoelectrocatalysis with pyridine (Py). The anion is prepared by the reaction of Py vapor with (CO(2))(m)(-) clusters carried out in an ionized, supersonic entrainment ion source. Comparison with the results of harmonic frequency calculations establishes that this species is a covalently bound molecular anion derived from the corresponding carbamate, C(5)H(5)N-CO(2)(-) (H(+)). These results confirm the structural assignment inferred in an earlier analysis of the cluster distributions and photoelectron spectra of the mixed Py(m)(CO(2))(n)(-) complexes [J. Chem. Phys. 2000, 113 (2), 596-601]. The spectra of the (CO(2))(m)(-) (m = 5 and 7) clusters are presented for the first time in the lower energy range (1000-2400 cm(-1)), which reveal several of the fundamental modes that had only been characterized previously by their overtones and combination bands. Comparison of these new spectra with those displayed by Py(CO(2))(n)(-) suggests that a small fraction of the Py(CO(2))(n)(-) ions are trapped entrance channel reaction intermediates in which the charge remains localized on the (CO(2))(m)(-) part of the cluster. 

Cluster distributions; Combination bands; Covalently bound; Fundamental modes; Harmonic frequency; Lower energies; Molecular anions; Photoelectrocatalysis; Photoelectron spectrum; Radical anions; Structural assignments; Vibrational predissociation; Freons; Ion sources; Photoelectron spectroscopy; Pyridine; Reaction intermediates; Ions; carbamic acid; carbon; carbon dioxide; hydrogen; nitrogen; pyridine; article; chemical reaction; complex formation; covalent bond; ionization; vapor