Synthesis and Properties of New Silyl-Substituted pi-Electron Systems and Organosilicon Reactive Intermediates

通过大环聚乙炔的分子内聚合，合成了富烯、二亚甲基环丁烯、三亚甲基环戊烯和[4]辐烯等几种新的硅烷基取代的π电子体系。这些环状π系统与锂的双电子还原产生有趣的阴离子物种。用X射线晶体学分析了二亚甲基环丁烯、三亚甲基环戊烯和[4]辐烯的二价阴离子的结构。发现了[4]radialene阴离子中的锂游走等有趣现象，1，3，4，6，7，9-hexasila-1，1，3，3，4，4，6，6，7，7，9，9-十二甲基三茚满阴离子为平面阴离子，在室温下具有稳定的三重态ESR谱。虽然基态是单重态，但单重态与三重态的能量差只有1 kcal/mole，这是迄今为止所观察到的最低值，生成了一些新的反应中间体，如二氨基取代的硅烯、三甲基硅基甲基取代的二硅烯和六甲基四硅杂-1，3-丁二烯，并对反应模式进行了研究。

Several new silyl-substituted pi-electron systems, such as fulvene, dimethylenecyclobutene, trimethylenecyclopentene, and [4]radialene, have been prepared by intramolecular polymerization of macrocyclic polyacetylenes. Two-electron reduction of these cyclic pi-systems with lithium creates interesting anionic species. Structures of the dianions of dimethylenecyclobutene, trimethylenecyclopentene, and [4]radialene are elucidated by X-ray crystallography. Interesting phenomena such as lithium-walk in the dianion of [4]radialene was observed.The dianion of l, 3, 4, 6, 7, 9-hexasila-1, l, 3, 3, 4, 4, 6, 6, 7, 7, 9, 9-dodecamethyltriindane was planar and exhibited stable triplet esr spectrum at room temperature. Although the ground state was singlet but the singlet-triplet energy difference was only 1 kcal/mole that was the lowest value ever observed.Several new reactive intermediates such as diamino-substituted silylenes, trimethylsilyl-methyl-substituted disilenes, and hexamethyltetrasila-1, 3-butadiene were generated and reaction modes were examined.