论文标题：Double aromaticity arising from σ- and π-rings

期刊：Communications Chemistry

作者：Shunsuke Furukawa, Masahiro Fujita, Yoshihiko Kanatomi, Mao Minoura, Miho Hatanaka, Keiji Morokuma, Kazuya Ishimura, Masaichi Saito

发表时间：2018/09/27

数字识别码： 10.1038/s42004-018-0057-4

原文链接：http://t.cn/E4wkrSm

最近《通讯-化学》发表的一项研究Double aromaticity arising from σ- and π-rings通过实验探究了双阳离子六（苯硒基）苯（hexakis(phenylselenyl)benzene）的双重芳香性。

自从19世纪苯被发现开始，芳香性便一直是化学的核心概念之一。同时，芳香性也影响了离域π电子体系的相关科学研究。传统芳香族化合物的芳香性通常源自由π-对称轨道组成的单个环的电子离域。尽管双重芳香性——即由两个环形离域电子轨道组成的芳香性——早在20年前已在理论层面被预测出来，但在实验层面仍未能很好地探究这类稳定化合物的双重芳香性。来自日本埼玉大学科学工程研究院的Masaichi Saito及其研究团队，报道了六（苯硒基）苯（hexakis(phenylselenyl)benzene）双阳离子的合成与分离，并且研究了其基于结构，能量和磁性标准的双重芳香性。在这个双阳离子中，环状σ-对称和π-对称离域电子轨道分别被10和6个电子占据，因此芳香性遵循休克尔4n + 2（n = 1,2，...）规则（Hückel rule），而不管σ-轨道或π-轨道的对称性。

图1：六原子取代苯中σ-轨道和π-轨道相互作用产生的双芳香性

摘要：Aromaticity has been a central concept in chemistry since the discovery of benzene in the 19th century and has impacted the science of delocalized π-electron systems. The aromaticity of conventional aromatic compounds usually originates from electron delocalization through a single ring that consists of π-symmetric orbitals. Although double aromaticity, i.e. aromaticity composed of two circularly delocalized orbitals, has been theoretically predicted for over 20 years, the double aromaticity of a bench-stable compound is not well explored by experiment. Here we report the synthesis and isolation of the dication of hexakis(phenylselenyl)benzene, as well as its double aromaticity based on structural, energetic, and magnetic criteria. In this dication, cyclic σ-symmetric and π-symmetric delocalized orbitals are formally occupied by ten and six electrons, respectively, and the aromaticity thus follows the 4n + 2 (n = 1, 2,…) electron Hückel rule, regardless of the σ-orbital or π-orbital symmetry.

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期刊介绍：Communications Chemistry (https://www.nature.com/commschem/) is an open access journal from Nature Research publishing high-quality research, reviews and commentary in all areas of the chemical sciences. Research papers published by the journal represent significant advances bringing new chemical insight to a specialized area of research.

（来源：科学网）