Enthalpy (H) and Entropy (S) for 详细信息    查看全文

• 作者：Benjamin W. Gung ; Xiaowen Xue ; Yan Zou
• 刊名：Journal of Organic Chemistry
• 出版年：2007
• 出版时间：March 30, 2007
• 年：2007
• 卷：72
• 期：7
• 页码：2469 - 2475
• 全文大小：226K
• 年卷期：v.72,no.7(March 30, 2007)
• ISSN：1520-6904

文摘

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Interactions between two aromatic rings with various substituents in a near-sandwich configuration havebeen quantitatively studied by using the triptycene derived molecular models. This model system allowsa stacking arrangement of two arenes to assume a near-perfect face-to-face configuration in its groundstate conformation. Comparing to our previous study of the parallel displaced configuration, repulsiveinteractions are predominant for most arenes currently studied. However, if one arene is strongly electrondeficient (Ar₂ = pentafluorobenzoate), attractive interactions were observed regardless of the characterof the other arene (Ar₁). For stacking interactions between Me₂NC₆H₄ and C₆F₅CO groups, a H of-1.84 ± 0.2 kcal/mol and a S of -2.9 ± 0.8 cal/(mol·K) were determined. The general trend in theattractive stacking interaction toward a pentafluorobenzoate is Me₂NC₆H₄ > Me₃C₆H₂ > Me₂C₆H₃ >MeC₆H₄ > MeOC₆H₄ > C₆H₅ > O₂NC₆H₄. The observed trend is consistent with a donor-acceptorrelationship and the acceptor is a C₆F₅CO group.