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、二甲基环丁烯、三亚甲基环戊烯和[4]放射烯等几种新的硅基取代聚电子体系。这些环状pi体系与锂的两电子还原反应产生了有趣的阴离子物种。二甲基环丁烯、三亚甲基环戊烯和[4]放射烯的双阴离子的结构通过X-射线结晶学进行了鉴定。L，3，4，6，7，9-六硅杂-1，L，3，3，4，4，4，6，6，7，7，9，9-十二烷基三丹的二阴离子是平面的，在室温下表现出稳定的三重态ESR谱。虽然基态为单重态，但单重态-三重态的能量差仅为1千卡/摩尔，是迄今观察到的最低值。生成了几种新的反应中间体，如二氨基取代硅烯、三甲基硅甲基取代二硅烯和六甲基四硅烷-1，3-丁二烯，并对反应模式进行了考察。

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.