桥联茂钛配合物催化丙烯聚合反应选择性的理论研究  

Theoretical Studies on the Regioselectivity and Stereoselectivity of the Olefin Polymerization Catalyzed by Bridged-metallocene Complexes

作　　者：唐艳辉[1] 王志栋[2] TANG Yanhui WANG Zhidong(School of Materials Science and Engineering, Beijing Institute of Fashion Technology, Beijing 100029, China State Key Laboratory of Chemical Resource Engineering, College of Science, Beijing University of Chemical Technology, Beijing 100029, China)

机构地区：[1]北京服装学院材料科学与工程学院,北京100029 [2]北京化工大学理学院,化工资源有效利用国家重点实验室,北京100029

出　　处：《高等学校化学学报》2016年第10期1849-1855,共7页Chemical Journal of Chinese Universities

基　　金：北京服装学院重点科研项目(批准号:2014A-01)资助~~

摘　　要：采用密度泛函方法对3种不同类型的硅桥联茂钛配合物[Me_2SiN(Me_4Cp)TiCl_2(A),Me_2SiCpFluTiCl_2(B)及Me_2SiInd_2TiCl_2(C)]催化丙烯聚合反应的选择性进行了理论研究.计算结果表明,硅桥联茂金属配体的空间结构是其催化烯烃聚合反应的区域选择性和立体选择性的主要原因.聚合过程中,α-烯烃配位有1,2插入(一级插入)和2,1插入(二级插入)2种方式,3种硅桥联茂金属催化剂均表现为烯烃的一级插入,这种区域选择性与催化剂硅桥联配体的刚性结构密切相关.对烯烃聚合反应链增长机理进行了理论计算,结果表明,具有Cs对称性的Me_2SiN(Me_4Cp)TiCl_2和Me_2SiCpFluTiCl_2催化丙烯聚合分别得到无规立构和间规立构的聚烯烃产物,而具有C_2对称性的Me_2SiInd_2TiCl_2催化丙烯聚合得到等规立构的聚烯烃产物,与实验结果一致.The reaction selectivity of olefin polymerization catalyzed by three different bridged-metallocene complexes [Me2SiN（Me4Cp）TiCl2, Me2SiCpFlu TiCl2 and Me2SiInd2TiCl2] were studied with density functional theory. The calculation results show that the ligand of the metalloence complex creates special stereo environment which leads to unique catalytic properties. There are two ways for olefin insertion,primary and secondary insertion,in the chain initiation and chain propagation steps of propylene polymerization catalyzed by bridged-metallocene catalyst. The calculation results suggest that bridged-metallocene catalysts show a preference of primary insertion way in chain initiation step of propylene polymerization,and we believe this regioselectivity is resulted from the rigid structure of catalyst. In the subsequent chain growth step,the catalysts start to show their stereoregularity,and the product of polymerization is atac-,syn-,iso-PP,respectively. By studying the interactions of the monomer,the ligand and the growing chain,we revealed the origin of the regioselectivity and stereospecificity of bridged-metallocene catalyst and provide theoretical support for design of tailor made metallocene catalyst.

关 键 词：硅桥联茂金属配合物 烯烃聚合反应 反应选择性 反应机理 理论研究 

分 类 号：O643.31[理学—物理化学]