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

(a)1，1，1-三硼基-2，2，2-三乙基二硅烷与钠缩合得到聚（三乙基硅基硅炔）（1），产率70%。1的凝胶渗透色谱法表明相对于聚苯乙烯，在具有1.04的多分散性的单个包封中Mw=1400。通过13 <29>Si、13 <13>C和131 H NMR光谱和红外光谱进行表征。1<29>的1H Si NMR谱显示出以+150 ppm为中心的宽共振，这被归属于低聚物主链的sp^2 Si原子。(b)测试了碘掺杂样品的电化学性能。完全掺杂的样品从1和碘的二氯甲烷溶液中得到黑色沉淀，样品在170 K以上显示出金属行为，这是首次在有机硅化合物中观察到的，并且变成半导体，活化能Ea为0.3 meV。(c)以十二异丙基三环[4.2.0.0 ^&lt;2，5&gt;]八硅烷（2）为原料，通过光化学反应合成了四硅环丁烯和八硅环辛-1，5-二烯等新型不饱和环聚硅烷.当2和甲醇在环己烷中的溶液在室温下用高压汞灯照射3 min时，2被干净地光解，仅得到1-甲氧基-1，2，3，3，4，4-六异丙基环四硅烷。环四硅烷的形成表明四硅杂环丁烯中间体的形成，其可以被甲醇捕获。发现顺式异构体的类似光解提供铅十二异丙基辛硅环辛-1，5-二烯中间体，其可被甲醇捕获。

(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.