C鈥揌 Bond Strengths and Acidities in Aromatic Systems: Effects of Nitrogen Incorporation in Mono-, Di-, and Triazines

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• 作者：Scott W. Wren ; Kristen M. Vogelhuber ; John M. Garver ; Shuji Kato ; Leonid Sheps ; Veronica M. Bierbaum ; W. Carl Lineberger
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：April 18, 2012
• 年：2012
• 卷：134
• 期：15
• 页码：6584-6595
• 全文大小：620K
• 年卷期：v.134,no.15(April 18, 2012)
• ISSN：1520-5126

文摘

The negative ion chemistry of five azine molecules has been investigated using the combined experimental techniques of negative ion photoelectron spectroscopy to obtain electron affinities (EA) and tandem flowing afterglow-selected ion tube (FA-SIFT) mass spectrometry to obtain deprotonation enthalpies (螖_acidH₂₉₈). The measured 螖_acidH₂₉₈ for the most acidic site of each azine species is combined with the EA of the corresponding radical in a thermochemical cycle to determine the corresponding C鈥揌 bond dissociation energy (BDE). The site-specific C鈥揌 BDE values of pyridine, 1,2-diazine, 1,3-diazine, 1,4-diazine, and 1,3,5-triazine are 110.4 卤 2.0, 111.3 卤 0.7, 113.4 卤 0.7, 107.5 卤 0.4, and 107.8 卤 0.7 kcal mol^鈥?, respectively. The application of complementary experimental methods, along with quantum chemical calculations, to a series of nitrogen-substituted azines sheds light on the influence of nitrogen atom substitution on the strength of C鈥揌 bonds in six-membered rings.