物理化学学报 >> 2002, Vol. 18 >> Issue (12): 1068-1070.doi: 10.3866/PKU.WHXB20021203

研究论文 上一篇    下一篇

新型镍催化剂催化乙烯聚合的阳离子机理

刘跃;刘佳雯;杨小震   

  1. 哈尔滨师范大学化学系,哈尔滨 150080; 中国科学院化学研究所高分子物理实验室,北京 100080
  • 收稿日期:2002-04-18 修回日期:2002-06-08 发布日期:2002-12-15
  • 通讯作者: 刘跃 E-mail:yuesd@0451.com

Cationic Reaction Mechanism for Ethylene Polymerization of New Nickel Catalysts

Liu Yue;Liu Jia-Wen;Yang Xiao-Zhen   

  1. Department of Chemistry, Harbin Normal University, Harbin 150080;Polymer Physics Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080
  • Received:2002-04-18 Revised:2002-06-08 Published:2002-12-15
  • Contact: Liu Yue E-mail:yuesd@0451.com

摘要: 含氮氧配位原子的镍催化剂是一类新型催化剂.文章以配体为[NH=CH-CH=CH-O]的镍催化剂为模型,用密度泛函方法(DFT)在B3LYP/LANL2MB水平上研究了该类乙烯聚合催化的反应机理.计算结果表明,催化的反应过程中,中心原子镍最先形成带空位的四边形阳离子配合物,乙烯以垂直于催化剂平面的方式占据空位,然后旋转到催化剂平面内以利于插入反应的进行;插入反应发生后,在催化剂中Ni和β-C之间形成一种氢桥键,协助新空位的形成,实现链的增长.

关键词: 镍催化剂, 乙烯聚合, 密度泛函(DFT)

Abstract: Transition metal catalyst based on nickel containing coordinated N and O atoms is a new type of polyolefin catalyst. We modeled a Ni catalyst with [NH=CH-CH=CH-O],and studied the reaction mechanism by the model catalyst using density functional method at the B3LYP/LANL2MB level. The results showed that at first the cationic complex forms a square-planar structure with a vacant site. An ethylene molecule attacks the vacant site, perpendicularly to the [Ni(N=C-C=C-O)] plane, and then it rotates into the plane for an insertion reaction. After insertion reaction, a β- agostic hydrogen bond is formed between Ni and Cβ-H7 so as to assist the regeneracy of a new vacant site and to realize the chain propagation.

Key words: Nickel catalysts, Ethylene polymerization, Density functional method (DFT)