Research on the Synthesis and Properties of Polysilanes Containing Conjugated Si-Si Double Bonds

(A)1，1，1-三溴-2，2，2-三乙基二硅烷与钠的缩合得到聚(三乙基硅烷)(1)，产率为70%。凝胶渗透层析1表明相对聚苯乙烯的相对分子质量为1400，在一个多分散度为1.04的单一包膜中。用~1H核磁共振谱和红外光谱对其进行了表征。1的~&lt；29&gt；Si核磁共振谱在+150ppm处有较宽的共振峰，归属于低聚物主链上的sp^2Si原子。(B)测量了碘掺杂样品的电化学性质。从1和碘的二氯甲烷溶液中得到了完全掺杂的样品，样品表现出金属行为，在170K以上首次观察到有机硅化合物的金属行为，激活能Ea为0.3 meV。(C)由十二异丙基三环[4.2.0.0^&lt；2，5&gt；]八硅硅烷(2)光化学合成了新型不饱和环聚硅烷，如四硅环丁烯和八硅环八-1，5-二烯。在高压汞灯下，2-甲氧基-1，2，3，3，4，4-六异丙基环四硅烷在环己烷中于室温下光照3min，得到1-甲氧基-1，2，3，3，4，4-六异丙基环四硅烷。环四硅烷的形成预示着四硅环丁烯中间体的形成，该中间体可被甲醇捕获。合成异构体的类似光解反应也得到了一个可被甲醇捕获的十二烷基异丙基硅烷环八烯-1，5-二烯中间体。

(a) Condensation of 1, 1, 1-tribormo-2, 2, 2-triethyldisilane with sodium afforded ploy (triethylsilylsilyne) (1) in 70% yield. Gel permeation chromatography of 1 indicated a Mw=1400 versus polystyrene,in a single envelope with polydispersity of 1.04. Characterization was achieved by ^<29>Si, ^<13>C, and ^1H NMR spectrocopy, and infrared spectrocopy. The ^<29>Si NMR spectrum of 1 exhibited broad resonance centered at +150 ppm, which was assigned to the sp^2 Si atoms of the oligomer backbone.(b) Electrochemical properties of iodine-doped sample of 1 was measured. The completely doped sample was obtained as black precipitate from the dichloromethane solution of 1 and iodine.The sample showed a metallic behavior, first observed for organosilicon compounds, above 170 K and became semiconducting eith an activation energy, Ea, of 0.3 meV.(c) Novel unsaturated cyclopolysilanes such as tetrasilacyclobutene and octasilacycloocta-1, 5-diene were generated photochemically from dodecaisopropyltricyclo [4.2.0.0^<2, 5>] octasilane (2). When a solution of 2 and methanol in cyclohexane was irradiated for 3 min at room temperature, with a high-pressure mercury lamp, 2 was cleanly photoalyzed to give 1-methoxy-1, 2, 3, 3, 4, 4-hexaisopropylcyclotetrasilane exclusively. The formation of the cycloterasilane is indicative of the formation of a tetetrasilacyclobutene intermediate, which could be trapped by methanol. Similar photolysis of the syn isomer was found to afford lead a dodecaisopropyloctasilacycloocta-1, 5-diene intermediate, which could be trapped by methanol.