Structure and chemistry of 1-silafluorenyl dianion, its derivatives, and an organosilicon diradical dianion.
Structure and chemistry of 1-silafluorenyl dianion, its derivatives, and an organosilicon diradical dianion.
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DOI：
10.1021/ja011821m
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发表时间：
2002-01
影响因子：
15
通讯作者：
Yuxia Liu;T. Stringfellow;David M. Ballweg;I. Guzei;R. West
中科院分区：
文献类型：
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作者：
Yuxia Liu;T. Stringfellow;David M. Ballweg;I. Guzei;R. West
以1,1-二氯-1-硅芴为原料，在回流THF中钾还原合成1-硅芴二离子。1,1-二钾-1-硅氧烷（3b）的x射线结构显示五元筒仓环中C-C键长度均衡，六元苯环中C-C键长度交替，表明电子在筒仓环中芳香离域。在29.0 ppm下的下场（29）Si化学位移和理论计算也支持3b的silole环中的电子离域。diion salt 3b与Me(3)SiCl和EtBr发生亲核反应，生成相应的双取代产物。苯甲醛在3b的存在下发生了还原偶联。3b的缓慢氧化生成1,1'-二钾-1,1'-双硅氧烷（16）。x射线结构和16的（29）Si化学位移（-38.0 ppm）表明硅原子处有局部负电荷，没有芳香特征。在18-冠-6存在下加热二甲醚/乙烷溶液，得到了一种新型的二自由基离子盐。
1-Silafluorene dianion was synthesized by potassium reduction of 1,1-dichloro-1-silafluorene in refluxing THF. The X-ray structure of 1,1-dipotassio-1-silafluorene (3b) shows C-C bond length equalization in the five-membered silole ring and C-C bond length alternation in the six-membered benzene rings, indicating aromatic delocalization of electrons in the silole ring. The downfield (29)Si chemical shift at 29.0 ppm and theoretical calculations also support electron delocalization in the silole ring of 3b. Dianion salt 3b underwent nucleophilic reactions with Me(3)SiCl and EtBr to form the corresponding disubstituted products. Benzaldehyde underwent reductive coupling in the presence of 3b. Slow oxidation of 3b yielded 1,1'-dipotassio-1,1'-bis(silafluorene) (16). The X-ray structure and (29)Si chemical shift (-38.0 ppm) of 16 indicate localized negative charges at the silicon atoms and no aromatic character. Heating a DME/hexane solution of 3b in the presence of 18-crown-6 led to a novel diradical dianion salt.