Synthesis of Ultrahigh Molecular Weight Ethylene-Based (Co)polymers with Titanium Complexes Bearing Nonsymmetric Amine-bis(phenolate) Ligands

作者：Feng Li, Yuhongxu Bai, Jianghao He, Tingting Song, Wei Gao, Xiaoyue Mu, Ying Mu · 发表于：Macromolecules · 年份：2023 · DOI：10.1021/acs.macromol.3c00579 · 被引用次数：14 · 研究领域：Organometallic Complex Synthesis and Catalysis、Carbon dioxide utilization in catalysis、Synthetic Organic Chemistry Methods

A series of novel Ti(IV) complexes bearing new type of nonsymmetric amine-bis(phenolate) tetradentate ligands, Me 2 NCH 2 CH 2 N[2-O-3-R 1 -5- t BuC 6 H 2 ] [CH 2 (2-O-3-R 2 -5- t BuC 6 H 2 )]TiCl 2 [R 1 = R 2 = t Bu ( 1 ); R 1 = R 2 = CPhMe 2 ( 2 ); R 1 = R 2 = CPh 2 Me ( 3 ); R 1 = CPh 3, R 2 = t Bu ( 4 ); R 1 = CPh 3, R 2 = CPhMe 2 ( 5 ); R 1 = CPh 3, R 2 = CPh 2 Me ( 6 ); and R 1 = R 2 = CPh 3 ( 7 )], have been synthesized and characterized by 1 H and 13 C NMR. The X-ray crystallography analysis on complexes 5 and 6 demonstrates that both complexes exhibit a distorted octahedral geometry around their central metals. When activated with methylaluminoxane (MAO), dry-MAO, MAO/2,6-Di tert -butyl-4-methylphenol (BHT), or Al i Bu 3 /CPh 3 B(C 6 F 5 ) 4, these new complexes display moderate to high catalytic activities for ethylene polymerization and produce ultrahigh molecular weight polyethylenes (up to 3.74 × 10 6 g mol –1 ). Polymers with low to moderate isotacticity are formed from the polymerization reactions of propylene or 1-hexane, and the isotacticity of the produced polymers increases with the increase in bulkiness of the ligands of the titanium complexes. For copolymerization reactions of ethylene/1-hexene or ethylene/1-octene, the MAO/BHT or dry-MAO activated catalytic systems show relatively high catalytic activities [10 6 –10 7 g of polymer (mol Ti) −1 h –1 ] and produce polyolefin thermoplastic elastomer (POE) or linear low-density polyethylene with high to ultra...