Syntheses and Properties of Cyclopolysilanes with Well-defined Structures as Models for σ-Conjugation

作为 σ 共轭模型的具有明确结构的环聚硅烷的合成和性能

基本信息

批准号：
09304058
负责人：
MATSUMOTO Hideyuki
金额：
$ 25.41万
依托单位：
Gunma University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A).
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 2000
项目状态：
已结题

项目摘要

1. In a series of the anti isomers of the ladder polysilanes, the absorption maxima of the longest wavelength shift to the longer wavelength region as the number of cyclotetrasilane rings progressively increases. The shift is explained in terms of the stabilization of the lowest unoccupied molecular orbitals (LUMO) by the extension of the Si-Si σ-conjugation. The ladder polysilanes can be readily reduced by Na and K to generate the radical anions. The remarkable feature of the resulting radical anions is their unusual stability. For example, in the absence of dioxygen, the half-life of the pentacyclododecasilane is too long to be measured. The X-ray crystallography disclosed that the anti ladder polysilanes can be seen as silicon double helices, in which two linear polysilane chains screw in one way and are bridged by Si-Si bonds. Chiral symmetry breaking could be realized for anti-tricyclooctasilane. The crystallization gave one large crystal of each enantiomer M or P.The oxidation of … More the bicyclohexasilane with a deficient amount of m-chloroperbenzoic acid (MCPBA) resulted in the formation of 7-oxa compound, which shows stronger UV absorption and fluorescence. The domino oxidation predominates in the tri-, tetra-, and penta-oxidations of the tricyclooctasilane, tetracyclodecasilane, and pentacyclododecasilane with MCPBA, respectively.2. From the stereochemical results observed in the ring-opening of the cis, cis- and cis, transcyclotrisilane [Ph (Thex) Si]_3 (Thex=1, 1, 2-trimethylpropyl) with halogens, it is concluded that the cleavage of the Si-Si bonds occurs with retention -inversion of the configuration of the Si atoms.3. Octathexyloctagermacubane was synthesized to allow a comparison of chemical and physical properties of the alkyl-substituted octasilacubane with those of the corresponding octagermacubane. The octagermacubane is very stable to UV-Visible light, suggesting the unusual electronic and photochemical properties of the polyhedral germanium framework. Less

1. 在梯形聚硅烷的一系列反异构体中，随着环四硅烷环的数量逐渐增加，最长波长的吸收最大值移动到较长波长区域，这种移动可以用最低未占据分子的稳定性来解释。通过 Si-Si σ-共轭的扩展，梯形聚硅烷可以很容易地被 Na 和 K 还原生成自由基阴离子，这是所得自由基的显着特征。例如，在没有分子氧的情况下，五环十二硅烷的半衰期太长而无法测量。X射线晶体学显示反梯形聚硅烷可以被视为硅双螺旋。两个线性聚硅烷链以一种方式螺旋并通过Si-Si键桥接，可以实现反三环辛硅烷的手性对称性破坏，结晶得到每种对映体的一个大晶体。 M或P。双环己硅烷与不足量的间氯过苯甲酸（MCPBA）的氧化导致形成7-氧杂化合物，该化合物显示出更强的紫外吸收和荧光。多米诺氧化在三-，三环辛硅烷、四环十硅烷和五环十二硅烷分别用MCPBA进行四氧化和五氧化。2．根据顺式、顺式和顺式、反式环三硅烷[Ph(Thex)Si]_3(Thex=1,1,2-三甲基丙基)与卤素开环观察到的立体化学结果，得出Si的裂解-Si键随着Si原子构型的保留反转而发生。3．合成了Octathexyloctagermacubane以比较其化学和物理性质。烷基取代的八硅立方烷与相应的八格玛立方烷对紫外-可见光非常稳定，这表明多面体锗骨架具有不寻常的电子和光化学性质。