Diazuleno-s-indacene Diradicaloids: Syntheses, Properties, and Local (anti)Aromaticity Shift from Neutral to Dicationic State
Diazuleno-s-indacene Diradicaloids: Syntheses, Properties, and Local (anti)Aromaticity Shift from Neutral to Dicationic State
复制标题
DOI：
10.1002/anie.201810220
复制
发表时间：
2018-12-17
影响因子：
16.6
通讯作者：
Chi, Chunyan
中科院分区：
文献类型：
--
作者：
Jiang, Qing;Tao, Tao;Chi, Chunyan
非交替的、非苯型π-共轭多环烃（PH）预期表现出与全苯型PH非常不同的电子性质。本文报道了两种与甘菊环稠合的S-引达省异构体的四种衍生物的合成和物理性质，即重氮并[2，1-a：2 ′，1 ′-g]-S-引达省（DAI-1）和重氮并[2，1-a：1 ′，2 ′-h]-S-引达省（DAI-2）。两种异构体的主链都含有28个π电子，并且是7-5-5-6-5-5-7稠环系统。X射线晶体学分析、NMR光谱和理论计算（ACID、NICS）揭示了具有两个芳香族甘菊环单元与中心反芳香族s-引达省部分稠合的结构。所有的化合物都表现出开壳双自由基的性质，是磁活性的，但DAI-2的衍生物显示出更大的自由基的字符比DAI-1的相应的。它们的dications被分离的结晶形式和所有的实验和理论分析揭示了本地（反）芳香性的位移沿着的骨干，与两个芳香族tropyridine环的末端。
Non-alternant, non-benzenoid pi-conjugated polycyclic hydrocarbons (PHs) are expected to exhibit very different electronic properties from all-benzenoid PHs. Reported herein are the syntheses and physical properties of four derivatives of two azulene-fused s-indacene isomers, the diazuleno[2,1-a:2',1'-g]-s-indacene (DAI-1) and diazuleno[2,1-a:1',2'-h]-s-indacene (DAI-2). The backbone of both isomers contains 28 pi electrons and is a 7-5-5-6-5-5-7 fused ring system. X-ray crystallographic analysis, NMR spectra, and theoretical calculations (ACID, NICS) reveal a structure with two aromatic azulene units fused with a central anti-aromatic s-indacene moiety. All compounds exhibit open-shell diradical character and are magnetically active, but the derivatives of DAI-2 show larger radical character than the respective ones of DAI-1. Their dications were isolated in crystalline form and all experimental and theoretical analyses disclose a shift of local (anti)aromaticity along the backbone, with two aromatic tropylium rings at the termini.