Details

Autor(en) / Beteiligte

• Ichino, Takatoshi
• Andrews, Django H
• Rathbone, G. Jeffery
• Misaizu, Fuminori
• Calvi, Ryan M. D
• Wren, Scott W
• Kato, Shuji
• Bierbaum, Veronica M
• Lineberger, W. Carl

Titel

Ion Chemistry of 1H-1,2,3-Triazole

Ist Teil von

• The journal of physical chemistry. B, 2008-01, Vol.112 (2), p.545-557

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2008

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• A combination of experimental methods, photoelectron-imaging spectroscopy, flowing afterglow-photoelectron spectroscopy and the flowing afterglow-selected ion flow tube technique, and electronic structure calculations at the B3LYP/6-311++G(d,p) level of density functional theory (DFT) have been employed to study the mechanism of the reaction of the hydroxide ion (HO-) with 1H-1,2,3-triazole. Four different product ion species have been identified experimentally, and the DFT calculations suggest that deprotonation by HO- at all sites of the triazole takes place to yield these products. Deprotonation of 1H-1,2,3-triazole at the N1−H site gives the major product ion, the 1,2,3-triazolide ion. The 335 nm photoelectron-imaging spectrum of the ion has been measured. The electron affinity (EA) of the 1,2,3-triazolyl radical has been determined to be 3.447 ± 0.004 eV. This EA and the gas-phase acidity of 2H-1,2,3-triazole are combined in a negative ion thermochemical cycle to determine the N−H bond dissociation energy of 2H-1,2,3-triazole to be 112.2 ± 0.6 kcal mol-1. The 363.8 nm photoelectron spectroscopic measurements have identified the other three product ions. Deprotonation of 1H-1,2,3-triazole at the C5 position initiates fragmentation of the ring structure to yield a minor product, the ketenimine anion. Another minor product, the iminodiazomethyl anion, is generated by deprotonation of 1H-1,2,3-triazole at the C4 position, followed by N1−N2 bond fission. Formation of the other minor product, the 2H-1,2,3-triazol-4-ide ion, can be rationalized by initial deprotonation of 1H-1,2,3-triazole at the N1−H site and subsequent proton exchanges within the ion−molecule complex. The EA of the 2H-1,2,3-triazol-4-yl radical is 1.865 ± 0.004 eV.