以酚膦化合物为双齿配体,合成与表征了一系列单组分中性镍烯烃聚合催化剂.研究表明,酚膦配体结构显著影响中性镍的催化性能,酚氧邻位无取代基的(2-PPh2-C6H4O) Ni(Me) (Py) (3a)活性较低,向酚氧邻位引入叔丁基或苯基等位阻基团可大幅度提高(2-PPh2-C6 H3 (R) O) Ni (Me) (Py) (3b～3d)的催化效率,最高催化活性可达4.46×106 g PE/(mol(Ni)·h).同时,聚乙烯的分子量也可以通过取代基效应进行适度调控,使用酚氧邻位带有苯基或蒽基的催化剂(3c ～3d)可获得较高分子量的聚乙烯.用供电子叔丁基替代二苯膦的一个苯环可提高催化活性中心镍原子的电子云密度,使辅助配体吡啶更容易离去,从而可在较低温度下引发乙烯聚合反应.此外,这类酚膦中性镍催化剂对极性基团具有较强的耐受性,可催化乙烯与极性5-降冰片烯-2-乙酸酯的共聚反应.
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