Effect of Cyclopentadienyl Fragment in Copolymerization of Ethylene with Cyclic Olefins Catalyzed by Non‐Bridged (Aryloxo)(cyclopentadienyl)titanium(IV) Complexes
Effect of Cyclopentadienyl Fragment in Copolymerization of Ethylene with Cyclic Olefins Catalyzed by Non‐Bridged (Aryloxo)(cyclopentadienyl)titanium(IV) Complexes
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DOI：
10.1002/adsc.200404275
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发表时间：
2005-02
影响因子：
5.4
通讯作者：
Wei Wang-;Tatsuo Tanaka;Miki Tsubota;M. Fujiki;S. Yamanaka;K. Nomura
中科院分区：
文献类型：
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作者：
Wei Wang-;Tatsuo Tanaka;Miki Tsubota;M. Fujiki;S. Yamanaka;K. Nomura
研究了不同非桥连芳氧羰基对乙烯-正丁烯（NBE）共聚反应中双键链段的影响。Cp'TiCl 2 -（OAr）[Cp'=茚基（1），C5 Me 5（Cp*，2），t-BuC 5 H4（3），1，2，4-Me 3C 5 H2（4））;探索了OAr=O-2，6-i-Pr 2 C6 H3]，-MAO催化剂体系。催化活性和NBE引入高度依赖于Cp'上所用的取代基，1显示出显著的催化活性和有效的NBE引入，提供具有单峰分子量分布的高分子量聚合物。在由1、3和4制备的所得聚（乙烯-co-NBE）中观察到NBE重复单元，并且所采用的Cp'强烈影响NBE二联体以及交替序列的程度。这些配合物（1，3，4）对乙烯/环戊烯（CPE）共聚合也表现出很高的催化活性，但在相同条件下，1引入CPE的效率低于NBE引入。采用从头算密度泛函（DF）分子轨道（MO）方法研究了Cp'上取代基对催化活性、NBE掺入和单体序列分布的影响。NBE插入后的ΔE c o r d E t（乙烯的配位能）与活性之间以及插入乙烯（或NBE插入）后的ΔE c o r d N B E（NBE的配位能）与NBE含量之间存在良好的相关性，表明NBE插入后的ΔE c o r d N B E决定了NBE重复单元的产生能力.
The effect of the cyclopentadienyl fragment in the copolymerization of ethylene with norbornene (NBE) by various non-bridged (aryloxo)(cyclopentadienyl)titanium(IV) complexes of the type, Cp'TiCl 2 -(OAr) [Cp'=indenyl (1),C 5 Me 5 (Cp*, 2), t-BuC 5 H 4 (3), 1,2,4-Me 3 C 5 H 2 (4); OAr=O-2,6-i-Pr 2 C 6 H 3 ], -MAO catalyst systems has been explored. The catalytic activity and the NBE incorporation were highly dependent upon substituent on Cp' employed, and 1 exhibited both a remarkable catalytic activity and an efficient NBE incorporation, affording high molecular weight polymers with unimodal molecular weight distributions. NBE repeat units were observed in the resultant poly(ethylene-co-NBE)s prepared by 1, 3, and 4, and the degree of NBE dyads as well as alternating sequences was strongly influenced by the Cp' employed. These complexes (1,3,4) also exhibited high catalytic activities for ethylene/cyclopentene (CPE) copolymerization, but the CPE incorporation by 1 was less efficient than the NBE incorporation under the same conditions. The ab initio density functional (DF) molecular orbital (MO) methods were utilized to explore the effect of substituents on Cp' toward the catalytic activity, the NBE incorporation and the monomer sequence distribution. Good correlations between the ΔE c o o r d E t (coordination energy of ethylene) after NBE insertion and the activity, and between ΔE c o o r d N B E (coordination energy of NBE) after ethylene (or NBE insertion) and NBE content were observed, strongly suggesting that the capability producing NBE repeat units was dependent upon ΔE c o o r d N B E after NBE insertion.