作者:Andrey A. Fokin、Lesya V. Chernish、Pavel A. Gunchenko、Evgeniya Yu. Tikhonchuk、Heike Hausmann、Michael Serafin、Jeremy E. P. Dahl、Robert M. K. Carlson、Peter R. Schreiner
DOI:10.1021/ja302258q
日期:2012.8.22
diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C-C bonds of up to 1.71 Å in 2-(1-diamantyl)[121]tetramantane. Yet, these dimers are thermally very stable even at temperatures above 200 °C, which is not in line with common C-C bond length versus bond strengths correlations. We suggest that the extraordinary stabilization arises from numerous
叔金刚石溴化物的金属诱导偶联产生高度空间拥挤的烃(杂)二聚体,在 2-(1-二金刚烷基)[121]四金刚烷中具有高达 1.71 Å 的超长中心 CC 键。然而,这些二聚体即使在高于 200 °C 的温度下也非常稳定,这与常见的 CC 键长与键强度的相关性不一致。我们认为这种非凡的稳定性源于相邻的 H 端接金刚石状表面之间的众多分子内范德华引力。1-(1-金刚烷基)二金刚烷、1-(1-金刚烷基)二金刚烷、2-(1-金刚烷基)三金刚烷、2-(1-二金刚烷基)三金刚烷和2-(1-二金刚烷基)的CC键旋转动力学[121]四金刚烷通过变温(1)H-和(13)C NMR光谱进行了研究。向内 (endo) CH 表面的形状决定了动态行为,将中央 CC 键旋转障碍从 7 更改为 33 kcal mol(-1)。我们用 6-31G(d,p) 探讨了流行的密度泛函理论 (DFT) 方法(包括 BLYP、B3L