Aromatic Compounds Consisting of Heavier Group 14 Elements

由14族重元素组成的芳香族化合物的化学已经有了显著的发展。1997年，我们合成了三（三叔丁基硅基）环三锗鎓离子[（^tBu_3SiGe）_3^+]，这是第一个由锗原子和自由锗阳离子组成的2π芳香体系。在本研究项目中，我们建立了环丙烯的重质类似物的制备方法，并研究了其转化为由重质14族元素组成的芳香族化合物。用~（4 tBu_2 MeSi）取代的二溴硅烷与~（4 tBu_2 MeSi）取代的三溴硅烷还原偶联，得到含硅不饱和三元环结构的四[二叔丁基（甲基）硅基]环三硅烯（1）。环三硅烯（1）与[Et_3Si（苯）]^+ TPFPB^-[TPFPB^-=（C_6F_5）_4B^-]反应，生成1，2，3-三[二叔丁基（甲基）硅基]-4，4-二叔丁基环四硅鎓 TPFPB^-（2^+ TPFPB^-），分离得到黄色晶体。晶体学分析和核磁共振研究表明，环四硅鎓离子（2^+）是一个在凝聚相中具有同芳香2π电子体系的“自由”硅基阳离子.发现环四硅鎓离子（2^+）经单电子还原生成环四硅烯基自由基（2^< >），经双电子还原生成环四硅烯离子（2^-）。我们成功地合成了第一个具有烯丙基型离域结构的可分离硅基环四硅烯基（2^< >）的红色晶体.我们还成功地合成了具有Si=Si双键的四[二叔丁基（甲基）硅基]-1-二硅锗烯（3），其通过热或光化学异构化为具有Si=Ge双键的四[二叔丁基（甲基）硅基]-2-二硅锗烯（4）。2-二硅锗芴（4）与苯乙炔反应，得到具有Si=Ge-C=C共轭体系的3-锗-1，2-二硅杂环戊二烯-2，4-二烯衍生物（5）。

The chemistry of aromatic compound consisting of heavier Group 14 elements has been remarkably developed. In 1997, we prepared tris (tri-tert-butylsilyl) cyclotrigermenyium ion [(^tBu_3SiGe)_3^+], which is the first example of a 2π aromatic system consisting of germanium atoms as well as a free germyl cation. In this research project, we have established the preparation of heavier analog of cyclopropene and also investigated its transformation to aromatic compounds consisting of heavier Group 14 elements.1. The reductive coupling of ^tBu_2MeSi-substituted-dibromosilane and-tribromosilane gave tetrakis [di-tert-butyl (methyl) silyl] cyclotrisilene (1) with an unsaturated three membered ring structure consisting of silicon. The reaction of cyclotrisilene (1) with [Et_3Si (benzene)]^+ TPFPB^-[TPFPB^-=(C_6F_5)_4B^-] produced 1, 2, 3-tris [di-tert-butyl (methyl) silyl]-4, 4-di-tert-butylcyclotetrasilenium TPFPB^-(2^+ TPFPB^-), which can be isolated as yellow crystals. The crystallographic analysis as well as NMR study reveal that cyclotetrasilenium ion (2^+) is a "free" silyl cation with a homoaromatic 2π-electron system in the condensed phase.2. Cyclotetrasilenium ion (2^+) was found to undergo stepwise reduction to give cyclotetrasilenyl radical (2^< >) by one electron reduction and cyclotetrasilenide ion (2^-) by two electron reduction, respectively. We succeeded in synthesizing red crystals of cyclotetrasilenyl radical (2^< >) as the first isolable silyl radical with an allyl type delocalized structure.3. We have also succeeded in synthesizing tetrakis [di-tert-butyl (methyl) silyl]-1-disilagermirene (3) with a Si=Si double bond, which is thermally or photochemically isomerized to tetrakis [di-tert-butyl (methyl) silyl]-2-disilagermirene (4) with a Si=Ge double bond. 2-Disilagermirene (4) reacted with phenylacetylene to give 3-germa-1, 2-disilacyclopent-2, 4-diene derivative (5) with a Si=Ge-C=C conjugated system.