Research on the Synthesis, Structure, and Reactivity of Aromatic Compound Consisting of Heavier Main Group Elements

苯、萘等芳香族碳氢化合物是有机化合物的基本基团，在有机化学中起着重要的作用。相比之下，稳定的金属芳香族化合物的化学是新的，并且是最近发展起来的。在这些化合物中，骨架原子(S)被较重的第14族元素部分取代。在本课题中，我们研究了由较重的14族元素组成的稳定芳香族化合物的化学组成、合成方法的发展、结构、性质和反应活性的分析。我们通过含有极大体积的三有机硅基的环三硅烯的氧化脱硅反应成功地合成并表征了环三硅烯离子。环三硅氧离子具有近正三角形的三元环，其芳香性类似于环丙烯离子的2π芳香族体系。另一方面，通过1，2，3，4-四溴环四硅烷的还原脱溴和额外的两电子还原反应合成了环丁二烯二阴离子与6π芳香族化合物的重的类似物四硅环丁二烯二钾盐，具有大的弯曲四元环，由上下两个钾离子配位，我们得出结论，较重的环丁二烯二阴离子是非芳香性的，这是因为在带负电荷的有机硅化合物中，平面三配位构型不是首选的。此外，我们还成功地合成了双硅杂环戊二烯离子作为6π电子芳香族化合物。

Aromatic hydorocarbons such as benzene and naphthalene, are fundamental group of organic compounds, and also plays important roles in organic chemistry. In contrast, the chemistry of stable metallaaromatic compounds such as sila- and germa- aromatic systems, in which skeletal atom(s) are partially replaced by heavier Group 14 elements, is new, and have been recently developed. In this project, we investigated the chemistry of stable aromatic compounds consisting of heavier group 14 elements ; the development of synthetic methods, analysis of structure, property, and reactivity of them.We succeeded in synthesize and characterize cyclotrisilenylium ion by the oxidative desilylation reaction of cyclotrisilene bearing extremely bulky triorganosilyl groups. Cyclotrisileniylium ion has near regular triangle three membered ring indicating its aromatic character in analogy with cyclopropenylium ion with 2π aromatic system. On the other hand, dipotassium salt of tetrasilacyclobutadiene dianion as heavier analogue of cyclobutadiene dianion with 6π aromatic system synthesized by the reductive debromination and additional two-electron reduction of 1,2,3,4-tetrabromocyclotetrasilane, has large bent four membered ring coordinated by two potassium cations up and below, and we concluded that heavier cyclobutadiene dianion is non-aromatic by the reason why planer three-coordinate geometry is not preferred in negatively charged organosilicon compounds. Additionally, we also succeeded in the synthesis of disilagermacyclopentadienide ion as 6π electron aromatic compound.