单环[11]环烯鎓阳离子中的芳香性和莫比乌斯反芳香性

Aromaticity and Möbius antiaromaticity in monocyclic [11]annulenium cations.

作者信息

Warner Philip M

机构信息

Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, USA.

出版信息

J Org Chem. 2006 Dec 8;71(25):9271-82. doi: 10.1021/jo061143s.

DOI:10.1021/jo061143s

PMID:17137352

Abstract

Monocyclic [11]annulenium cations, which are experimentally unknown, have been studied primarily via DFT methods but also with some CCSD(T) validation. We have located six minima: two doubly trans (26, 27), one triply trans (28), one singly trans (29), one quintuply trans (trannulene-type, 33), and one all-cis (31). The first three are aromatic, 33 is modestly aromatic, 29 is nonaromatic, and the last is a Möbius antiaromatic species. We also investigated the fusion of various numbers of three-membered rings (3MRs) to the central 11-membered ring (11MR). We found several planar, all-cis-[11]annulenium ion derivatives as well as another Möbius antiaromatic species (52b); for comparison, we also found planar, antiaromatic all-cis-[12]annulene (60) and [15]annulenium cation (61) derivatives. The (anti)aromatic characterization of these compounds is based mainly on calculated magnetic data for the ground singlet and vertical triplet states, although aromatic stabilization energies (ASE) are also considered. Data for optimized triplets, several of which are Möbius aromatic systems (31t, 52t, 63t, 64t), are also included. Several of these cations are reasonable synthetic targets.

摘要

单环[11]轮烯鎓阳离子在实验上尚未被发现，主要通过密度泛函理论（DFT）方法进行研究，但也有一些耦合簇单双取代微扰理论（CCSD(T)）验证。我们找到了六个极小值：两个双反式（26、27），一个三反式（28），一个单反式（29），一个五反式（类跨环烯型，33），以及一个全顺式（31）。前三个是芳香性的，33是中等芳香性的，29是非芳香性的，最后一个是莫比乌斯反芳香性物种。我们还研究了各种数量的三元环（3MR）与中心的十一元环（11MR）的稠合。我们发现了几种平面的、全顺式-[11]轮烯鎓离子衍生物以及另一种莫比乌斯反芳香性物种（52b）；作为比较，我们还发现了平面的、反芳香性的全顺式-[12]轮烯（60）和[15]轮烯鎓阳离子（61）衍生物。这些化合物的（反）芳香性特征主要基于基态单重态和垂直三重态的计算磁数据，不过也考虑了芳香稳定化能（ASE）。还包括了优化后的三重态数据，其中有几种是莫比乌斯芳香体系（31t、52t、63t、64t）。这些阳离子中的几种是合理的合成目标。