Structures and Rotational Barriers of a Diiodobinorsnoutane: Energetic Preference for Gauche Conformation

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• 作者：Joseph P. Herres ; Caitlin A. Moran ; Mark A. Forman ; James E. Hall ; John P. McCauley Jr. ; Don E. Pivonka ; Steven S. Wesolowski
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：August 5, 2016
• 年：2016
• 卷：81
• 期：15
• 页码：6862-6866
• 全文大小：299K
• 年卷期：0
• ISSN：1520-6904

文摘

The diiodobinorsnoutane, bi(5-iodopentacyclo[4.3.0.0^2,4.0^3,8.0^5,7]non-4-yl) (5), exists in a sterically hindered gauche conformation rather than an anti or an averaged (freely rotating) C_2v structure. Density functional theory (DFT) predictions place the gauche conformation 11 kcal/mol more stable than the anti conformation with a barrier of 17 kcal/mol connecting the minima. These are consistent with variable-temperature NMR (17.1 ± 0.8 kcal/mol) estimates and X-ray analysis. Predictions of the torsional profiles of the yet-unsynthesized bromo-, chloro-, and fluoro- analogues show a progressive lowering of the barriers.