Cationic Clusters Consisting of Heavier Group 14 Elements

研究了重14族元素的稳定离子物种的化学，包括阳离子和阴离子物种以及自由基物种。通过实验和计算研究了这些离子物种在固态和溶液中的电子结构和晶体结构特征。高度拥挤的3，3-bis(di-tert-butylmethylsily1)-1，2-bis(tri-tert-butylsilyl)cyclotrisilene，是一种具有Si=Si键的不饱和三元化合物，用三苯基甲基四芳基硼酸根处理产生了(di-tert-butylmethylsilyl)bis(tri-tert-butylsilyl)cyclotrisilenylium离子，这是环丙烯离子的第一个可分离的硅同系物。X-射线晶体结构和光谱数据表明，环三硅烯离子不仅是一个游离的硅基阳离子，而且是一个2a电子芳香族物种，正电荷在三元骨架上离域。用石墨钾还原脱卤化相应的前驱体，合成了重环丁二烯双阴离子tetrakis(di-tert-butylmethylsily1)-1，2-disila-3，4-digermacyclobutadiene双阴离子和tetrakis(di-tert-butylmethylsilyl)tetrasilacyclobutadiene双阴离子。根据环丁二烯双阴离子的结构特点，发现它们是非芳香族的，并且没有环电流效应。三[二叔丁基(甲基)硅基]硅基和锗基阴离子与二氯锗二氧六环络合物发生单电子氧化反应，生成稳定的三[二叔丁基(甲基)硅基]硅和锗自由基。硅基和Germyl自由基的晶体结构都显示出围绕自由基中心的完全平面几何构型。EPR谱表明两个自由基的a-特征，对应于自由基中心的平面几何和sp2杂化。

The chemistry of the stable ionic species of heavier group 14 elements has been studied, including both cationic and anionic species together with radical species. The electronic and crystal structural features of these ionic species, both in the solid state and in solution, have been investigated by the experimental and computational study.1. The highly crowded 3,3-bis(di-tert-butylmethylsily1)-1,2-bis(tri-tert-butylsilyl)cyclotrisilene, an unsaturated three-membered compound with an Si=Si bond, was treated with triphenylmethylium tetraarylborate to produce (di-tert-butylmethylsilyl)bis(tri-tert-butylsilyl)cyclotrisilenylium ion, representing the first isolable silicon congener of the cyclopropenylium ion. The X-ray crystal structure and spectral data show that the cyclotrisilenylium ion is not only a free silyl cation but also a 2a electron aromatic species with delocalization of the positive charge over the three-membered skeleton.2. The heavy cyclobutadiene dianions, tetrakis(di-tert-butylmethylsily1)-1,2-disila-3,4-digermacyclobutadiene dianion and tetrakis(di-tert-butylmethylsilyl)tetrasilacyclobutadiene dianion, have been synthesized by the reductive dehalogenation of the corresponding precursors with potassium graphite. The cyclobutadiene dianions were found to be nonaromatic by their structural features and the lack of diatropic ring current effects.3. 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(methypsilyl]sily1 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 a-character of both radicals, corresponding to a planar geometry and sp2 hybridization of the radical centers.