demonstrated. When cations 4 and 5 were generated by the use of triphenylmethyl perchlorate instead of triphenylmethyl TPFPB, covalent perchlorate esters 18 and 19 having the O–Si covalent bond were formed instead of ionic salts. By treatment with water, the perchlorate ester 18 was found to undergo a novel rearrangement to give a cyclopentene derivative 20a spiro-connected with bicyclo[2.2.2]octane at the 3-position
用四(五氟苯基)硼酸酯(TPFPB)作为抗衡阴离子,制备了第一个环状π-共轭硅烷基离子,即在硅原子上带有三个均三甲苯基的三个双环[2.2.2]辛烯单元退火的硅烷基trop离子5在-50°C下通过氢化从相应的硅杂环庚三烯(silepin)中提取2 Cl 2。观察到的阳离子5的1 H,13 C和29 Si NMR化学位移与计算值一致。这些结果和NICS计算表明,阳离子5的芳香性接近对苯二甲基离子的芳香性。阳离子4时在存在两个当量的乙腈的情况下,生成具有甲基而不是均三甲苯基的阳离子和阳离子5,形成具有相当大的共价键特性的乙腈配合物16和17。对于配合物16和17,首次观察到乙腈作为甲硅烷基阳离子的乙腈配合物的交换过程,并且证明了五价硅的中间体。当通过使用高氯酸三苯甲基酯代替三苯基甲基TPFPB生成阳离子4和5时,共价高氯酸酯18和19形成具有O-Si共价键的取代离子盐。通过用水处理,发现高氯酸酯
Effects of Substituents on Silicon upon the Ring Inversion of Silepins Annelated with Bicyclo[2.2.2]octene Frameworks
The energy barrier for ring inversion of the silepin annelated with bicyclo[2.2.2]octene was found to decrease as the electro-negativity of substituents on silicon increases.