| 168330-94-7

• CAS: 168330-94-7
• 化学式: C₂₃H₄₄Si₄Zr
• 分子量: 524.168
• InChiKey: JSTGWOMYTOEEDI-UHFFFAOYSA-N

计算性质

• 辛醇/水分配系数(LogP)：
  None
• 重原子数：
  None
• 可旋转键数：
  None
• 环数：
  None
• sp3杂化的碳原子比例：
  None
• 拓扑面积：
  None
• 氢给体数：
  None
• 氢受体数：
  None

反应信息

• 作为产物：
  描述：

  、 甲基溴化镁 以 乙醚 为溶剂， 以43%的产率得到
  参考文献：
  名称：

  Metal-Catalyzed Dehydropolymerization of Secondary Stannanes to High Molecular Weight Polystannanes

  摘要：

  The first high molecular weight polystannanes, H(SnR(2))(n)H (R = (n)Bu, (n)Hex, (n)Oct), result from dehydropolymerization of secondary stannanes R(2)SnH(2) by zirconocene catalysts. Good catalysts include zirconocenes based on both CpCp*Zr (Cp* = eta(5)-C(5)Me(5)) and Cp(2)Zr fragments, and the most active catalyst with respect to production of high molecular weight polystannanes was Me(2)C(eta(5)-C5H4)(2)Zr[Si(SiMe(3))(3)]Me. The latter catalyst produced H(Sn(n)Bu(2))(n)H chains (M(w)/M(n) = 66 900/20 300) that were contaminated by ca. 18% (by weight) low molecular weight cyclic oligomers. Lower molecular weights resulted from dehydropolymerizations of Me(2)SnH(2), PhMeSnH(2), and Ph(2)SnH(2). At room temperature, H(SnR(2))(n)H (R alkyl group) polystannanes have lambda(max) values at ca. 380-400 nm, attributed to sigma --> sigma* transitions. Thermal gravimetric analyses on the polystannanes reveal that these polymers are as thermally stable as related poly(dialkylsilane)s and have onset temperatures for thermal decomposition in the range 200-270 degrees C, under both nitrogen and air. The H(Sn(n)Bu(2))(n)H polymer has been shown to be a good precursor to SnO2, as shown by bulk pyrolysis in air (ceramic yield: 56%). Preliminary results also indicate that these polymers may be useful as precursors to elemental tin. The polystannanes are photosensitive, and their photobleaching behavior has been characterized by UV-vis spectrometry and Sn-119 NMR spectroscopy, which demonstrated that H(Sn(n)Bu(2))(n)H is photochemicaly depolymerized to a 2:1 mixture of cyclo-(Sn(n)Bu(2))(5) and cyclo-(Sn(n)Bu(2))(6). The polymers H(Sn(n)Hex(2))(n)H and H(Sn(n)Oct(2))(n)H exhibit thermochromic behavior which is visibly evident as a discoloration from yellow to colorless upon warming above room temperature. This reversible behavior is associated with an abrupt change in lambda(max) (e.g., from 402 to 378 nm for films of H(Sn(n)Oc(2))(n)H) and a phase change at ca. 40 OC (by differential scanning calorimetry). Thin films of H(Sn(n)Bu(2))(n)H and H(Sn(n)Oct(2))(n)H on glass slides were doped by exposure to SbF5 vapor to conductivities of 10(-2) and 0.3 S cm(-1), respectively. Preliminary experiments suggest that the dehydropolymerization occurs by a sigma-bond metathesis mechanism involving four-center transition states. A previous report on production of high molecular weight poly(dibutylstannane) by the reductive coupling of (n)Bu(2)SnCl(2) by Na/15-crown-5 was reinvestigated and found to produce only low molecular weight material with M(w)/M(n) = 2400/ 1200.

  DOI：

  10.1021/ja00145a001