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Synthesis, Structure, and Reactivity of Heavier Group 14 Element-centered Free Radicals : From Phantom Species to Grams-Order-Scale Materials

以较重第 14 族元素为中心的自由基的合成、结构和反应性：从幽灵物种到克级材料

基本信息

批准号：
16205008
负责人：
SEKIGUCHI Akira
金额：
$ 32.61万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

The chemistry of the stable free radicals of heavier group 14 elements has been studied, including both neutral and charged radical species. The electronic and crystal structural features of these radicals, both in the solid state and in solution, are compared with each other. The most important parameters affecting the stability, geometry and electronic configuration of the radicals are investigated, based upon the experimental and computational data.1. Upon one-electron reduction with ^tBuLi, tetrakis(di-tert-butylmethylsilyl)disilene produced a disilene anion radical, which was isolated in the form of its lithium salt. The molecular structure was established by X-ray crystallography, which showed a nearly orthogonal structure with the central Si-Si bond length of 2.341(5) Å. One of the central Si atoms has radical character, whereas the other Si atom has silyl anion character. The EPR study indicates that rapid spin exchange occurs between these central Si atoms on the EPR time scale.2. The one-electron oxidation reaction of tris[di-tert-butyl(methyl)silyl]silyl and germyl anions with dichlorogermylene dioxane complex resulted in the formation of stable tris[di-tert-butyl(methyl)silyl]silyl and germyl radicals. The crystal structures of both silyl and germyl radicals showed a completely planar geometry around the radical centers. The EPR spectra indicate the p-character of both radicals, corresponding to a planar geometry and sp^2 hybridization of the radical centers.3. The one-electron reduction of tris[di-tert-butyl(methyl)silyl]aluminum and-gallium with alkali metals (Li, Na, K) resulted in the formation of the corresponding radical anions [(tBu_2MeSi)_3Al]^-・and [(^tBu_2MeSi)_3Ga]・^-. Their molecular structures were established by X-ray crystallography, which showed a nearly planar geometry around the radical centers.

较重的第 14 族元素的稳定自由基的化学性质已得到研究，包括中性和带电自由基物质。对这些自由基在固态和溶液中的电子和晶体结构特征进行了相互比较。基于实验和计算数据，研究了影响自由基稳定性、几何形状和电子构型的最重要参数。 1．当用叔丁基锂进行单电子还原时，四(二叔丁基甲基甲硅烷基)二硅烯产生二硅烯阴离子自由基，其以其锂盐的形式被分离。通过X射线晶体学确定了该分子结构，显示出接近正交的结构，中心Si-Si键长为2.341(5) Å。中心硅原子之一具有自由基特征，而另一个硅原子具有甲硅烷基阴离子特征。 EPR研究表明，在EPR时间尺度上，这些中心Si原子之间发生了快速的自旋交换。2．三[二叔丁基(甲基)甲硅烷基]甲硅烷基和甲芽基阴离子与二氯甲锗烷二恶烷络合物的单电子氧化反应导致形成稳定的三[二叔丁基(甲基)甲硅烷基]甲硅烷基和甲芽基自由基。甲硅烷基和甲锗烷基自由基的晶体结构在自由基中心周围表现出完全平面的几何形状。 EPR谱表明两个自由基的p特征，对应于自由基中心的平面几何形状和sp^2杂化。3．三[二叔丁基(甲基)甲硅烷基]铝和-镓与碱金属(Li、Na、K)的单电子还原导致形成相应的自由基阴离子[(tBu_2MeSi)_3Al]^-·和[(^tBu_2MeSi)_3Ga]·^-。它们的分子结构是通过 X 射线晶体学确定的，显示出自由基中心周围几乎是平面的几何形状。