4,4'-二(亚甲基)联苯桥连双核茂金属钛化合物的合成及催化乙烯聚合

以四氢呋喃(THF)为溶剂,由CpTiCl 3和CpZrCl3·DME分别与NaCp(CH2 Ph-p-PhCH2)CpNa]反应,合成了新型的4,4'二(亚甲基)联苯桥连双核茂金属钛、锆化合物--(C5 H 5)MtCl2](C5 H4)CH2-C6H4-C6 H4-CH2(C5H4)](C5H5)MtCl2]Mt=Ti(3),Zr(4)].用1H NMR和元素分析进行了表征.以配合物(3)为催化剂,经甲基铝氧烷(MAO)活化,能催化乙烯聚合.系统考察了催化剂浓度、Al]/Cat]摩尔比、温度和时间对(3)/MAO催化乙烯聚合反应的影响.结果表明化合物(3)催化活性高于1,4'-二(亚甲基)苯桥连双核钛(5)/MAO、1,4'-二(亚甲基)苯桥连双核锆(6)/MAO和Cp2TiCl2/MAO、Cp2ZrCl2/MAO的催化体系.升高温度引起聚乙烯相对分子质量的下降.随着聚合时间的延长,聚乙烯的相对分子质量增大.(3)/MAO催化所得聚乙烯的相对分子质量分布较宽为4.28.

Synthesis of 4, 4 '-Bis (methylene) biphenylene bridged homodinuclear titanocene and as catalyst for ethylene polymerization

Ethylene polymerization was studied by using 4,4'-bis(methylene) biphenylene bridged homodinuclear titanocene(3)/methyl aluminoxane(MAO) catalyst system,which could be conveniently prepared by treatment of CpTiCl_3 with NaCp(CH_(2)Ph-p-PhCH_2)CpNa] in THF and well characterized by ~1H NMR and element analysis.The influence of reaction conditions,such as temperature,time,catalyst concentration and molar ratio of / on ethylene polymerization was investigated systematically.The catalytic activity of (3) is higher than that of 1,4-phenylenedimethylene bridged titanocene(5)/MAO,1,4'-phenylenedimethylene bridged zirconocene(6)/MAO,Cp_2TiCl_2/MAO and Cp_2ZrCl_2/MAO systems.High temperature resulted in the decrease of molecular weight of PE.The prolongation of polymerization time was favorable for the increase of the molecular weight of PE simultaneously.GPC spectrum of polyethylene demonstrated that the dinuclear titanocene(3)/MAO provided polyethylene with broad molecular weight distribution(4.28).