文献类型：期刊文献

中文题名：Ethylene-bridged Indenyl-fluorenyl Metallocene Complexes for Efficient Preparation of Allyl-terminated Propylene Oligomers and Polymers via Selective β-Methyl Transfer

英文题名：Ethylene-bridged Indenyl-fluorenyl Metallocene Complexes for Efficient Preparation of Allyl-terminated Propylene Oligomers and Polymers via Selective β-Methyl Transfer

作者：Lei Zhang[1];Bin Zhang[1];Haiyan Ma[1]

机构：[1]Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, School of Chemistry and Molecular Engineering,East China University of Science and Technology

年份：2019

卷号：37

期号：6

起止页码：578

中文期刊名：Chinese Journal of Polymer Science

外文期刊名：高分子科学（英文版）

收录：CSTPCD;;Scopus;CSCD:【CSCD2019_2020】；

基金：financially supported by the National Natural Science Foundation of China (No. 21274041);the Key Project of Chinese Ministry of Education (No. 109064);the Fundamental Research Funds for the Central Universities (No. WK1214048)

语种：英文

中文关键词：Metallocene;Ethylene-bridged indenyl-fluorenyl ligand;Propylene;Oligo-/polymerization;β-Methyl transfer

外文关键词：Metallocene;Ethylene-bridged;indenyl-fluorenyl;ligand;Propylene;Oligo-/polymerization;β-Mcthyl;transfer

摘要：Four C_1-symmetric ansa-metallocene complexes, C_2H_4(Ind)(2,7-~tBu_2-Flu)ZrCl_2(4), C_2H_4(3-Bn-Ind)(2,7-~tBu_2-Flu)ZrCl_2(5),C_2H_4(3-Bn-Ind)(3,6-~tBu_2-Flu)ZrCl_2(6), and C_2H_4(3-Bn-Ind)(2,7-~tBu_2-Flu)HfCl_2(7), were synthesized and characterized. The structures of complexes 4, 5, and 7 were further determined via X-ray diffraction studies. Upon activation with modified methylaluminoxane(MMAO) or Al^iBu_3/[Ph_3C][B(C_6F_5)_4](TIBA/TrB), most of these complexes showed high efficiency in catalyzing propylene oligomerization/polymerization to afford products dominantly with allyl terminals via selective β-methyl transfer(β-Me transfer). The introduction of 3-benzyl group on the indenyl ring of the complexes was found to be crucial in enabling highly selective β-Me transfer during the polymerization process, leading to selectivities up to 89% obtained by zirconocene complexes 5 and 6, and up to 91% obtained by hafnocene complex 7. Detailed chain-end analysis by ~1H-NMR, ^(13)C-NMR, and MALDI-TOF mass spectroscopy revealed that the allyl chain-ends of the polymeric products resulted from a selective β-Me transfer process after two successively primary insertions of the monomer. Further studies concerning the dependence of chain release selectivity as well as the molecular weight of products on monomer concentration suggested that both β-Me transfer(major) and β-hydrogen transfer(β-H transfer)(minor) mediated by 5/MMAO and 6/MMAO systems may mainly operate in a bimolecular pathway.
Four C_1-symmetric ansa-metallocene complexes, C_2H_4(Ind)(2,7-~tBu_2-Flu)ZrCl_2(4), C_2H_4(3-Bn-Ind)(2,7-~tBu_2-Flu)ZrCl_2(5),C_2H_4(3-Bn-Ind)(3,6-~tBu_2-Flu)ZrCl_2(6), and C_2H_4(3-Bn-Ind)(2,7-~tBu_2-Flu)HfCl_2(7), were synthesized and characterized. The structures of complexes 4, 5, and 7 were further determined via X-ray diffraction studies. Upon activation with modified methylaluminoxane(MMAO) or Al^iBu_3/[Ph_3C][B(C_6F_5)_4](TIBA/TrB), most of these complexes showed high efficiency in catalyzing propylene oligomerization/polymerization to afford products dominantly with allyl terminals via selective β-methyl transfer(β-Me transfer). The introduction of 3-benzyl group on the indenyl ring of the complexes was found to be crucial in enabling highly selective β-Me transfer during the polymerization process, leading to selectivities up to 89% obtained by zirconocene complexes 5 and 6, and up to 91% obtained by hafnocene complex 7. Detailed chain-end analysis by ~1H-NMR, ^(13)C-NMR, and MALDI-TOF mass spectroscopy revealed that the allyl chain-ends of the polymeric products resulted from a selective β-Me transfer process after two successively primary insertions of the monomer. Further studies concerning the dependence of chain release selectivity as well as the molecular weight of products on monomer concentration suggested that both β-Me transfer(major) and β-hydrogen transfer(β-H transfer)(minor) mediated by 5/MMAO and 6/MMAO systems may mainly operate in a bimolecular pathway.