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

(a) 1,1,1 -三溴- 2,2,2 -三乙基二硅烷与钠缩合得到聚（三乙基硅烷）(1)，产率为70%。凝胶渗透色谱1表明，相对于聚苯乙烯，在单个包膜中，Mw=1400，多分散性为1.04。表征是通过^<29>Si, ^<13>C，和^1H NMR光谱和红外光谱来实现的。1的^<29>Si核磁共振谱在+150 ppm处显示出宽共振，这被分配给低聚物主链的sp^2 Si原子。(b)测量了碘掺杂样品1的电化学性能。完全掺杂的样品以黑色沉淀的形式从碘和1的二氯甲烷溶液中得到。该样品在170 K以上表现出金属行为，首次在有机硅化合物中观察到，并以0.3 meV的活化能Ea变成半导体。(c)由十二烷基异丙基三环[4.2.0.0^< 2,5 >]辛硅烷光化学合成新的不饱和环聚硅烷，如四硅环丁烯和辛硅环- 1,5 -二烯(2)。将2和甲醇在环己烷中的溶液在室温下用高压汞灯照射3min后，2被干净地光分析，得到1-甲氧基- 1,2,3,3,4,4 -六异丙基环四硅烷。环三聚硅烷的形成表明了四聚硅环丁烯中间体的形成，它可以被甲醇捕获。类似的光解作用还可以得到十二异丙基硅酸酯- 1,5 -二烯中间体，该中间体可以被甲醇捕获。

(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.