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化学学报
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化学学报 ›› 2011, Vol. 69 ›› Issue (18): 2085-2091. 上一篇    下一篇

研究论文

β-二酮亚胺钛化合物催化乙烯和环戊二烯共聚合反应机理的密度泛函理论研究

王永霞1,2，段雪梅*,1，王钦1，李悦生2，刘靖尧1   

  1. (1吉林大学理论化学研究所 理论化学计算国家重点实验室 长春 130023)
    (2中国科学院长春应用化学研究所 长春 130022)
  • 投稿日期:2011-01-03 修回日期:2011-03-26 发布日期:2011-05-23
  • 通讯作者: 刘靖尧 E-mail:ljy121@jlu.edu.cn
  • 基金资助:

    国家自然科学基金;国家自然科学基金;国家自然科学基金

DFT Study on the Copolymerization Mechanism of Ethylene with Cyclopentadiene by the Titanium Complexes Bearing Two β-Enaminoketonato Ligands

Wang Yongxia1,2 Duan Xuemei*,1, Wang Qin1 Li Yuesheng2 Liu Jingyao1   

  1. (1 Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023)
    (2 Changchun Institute of Applied Chemistry, Changchun 130022)
  • Received:2011-01-03 Revised:2011-03-26 Published:2011-05-23
  • Contact: Jing-Yao LIU E-mail:ljy121@jlu.edu.cn

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运用密度泛函理论(DFT)对β-二酮亚胺钛化合物[PhNC(CH3)CHC(CF3)O]2TiCl2催化乙烯(E)和环戊二烯(CPD)共聚合反应的反应机理进行了理论研究. 计算结果表明: 乙烯和CPD的共聚反应中, CPD插入反应可以通过1,2插入和2,1插入两种路径进行, 1,2插入能垒略低于2,1插入, 因此我们预测两种路径应都可以在实验中发生且1,2插入占优. 同时, 对共聚合过程的研究表明, 乙烯插入聚合物链的反应相对环戊二烯具有较低的活化能, 更容易发生, 共聚合产物中应含有较多的乙烯片段. 环戊二烯在聚合物链和金属中心相连为乙烯片段时有一定的几率发生, 而在聚合物链和金属中心相连为环戊二烯片段时很难发生, 因此环戊二烯的插入反应不能连续发生, 共聚合产物的聚合物链中没有连续的CPD片段存在.

关键词: 密度泛函理论, 过渡金属催化剂, 共聚合反应, 乙烯, 环戊二烯

We employed DFT calculations for copolymerization mechanism of ethylene (E) with cyclopentadiene (CPD) catalyzed by [PhNC(CH3)CHC(CF3)O]2TiCl2. Our calculations show that the CPD can incorporate into polymer chain via both 1,2 and 2,1-insertion, and it is predicted that 1,2-insertion might be a preferred pathway due to the lower barrier. And in the copolymerization process, reaction barriers of ethylene insertion into both Metal-E and Metal-CPD bonds are lower than the barriers of CPD insertion, consequently, there might be more E sequences in the growing polymer chain. The CPD insertion into Metal-E bond can occur a certain extent due to the relative low insertion barrier, while for the process of CPD insertion into Metal-CPD chain, its insertion barrier is too high to make this reaction occur. The present conclusion is in line with the experimental fact that no consecutive sequence of CPD has been observed in the polymer product.

Key words: density functional theory, transition metal catalyst, copolymerization, ethylene, cyclopentadiene

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