Balancing high thermal stability with high activity in diaryliminoacenaphthene‐nickel(II) catalysts for ethylene polymerization |
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Authors: | Chuanbing Huang Gregory A. Solan Xiang Hao Wen‐Hua Sun |
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Affiliation: | 1. Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China;2. Department of Chemistry, University of Leicester, Leicester, United Kingdom;3. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China |
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Abstract: | The N,N‐diaryliminoacenaphthenes, 1,2‐[2,4‐{(4‐FC6H4)2CH}2‐6‐MeC6H4N]2‐C2C10H6 ( L1 ) and 1‐[2,4‐{(4‐FC6H4)2CH}2‐6‐MeC6H4N]‐2‐(ArN)C2C10H6 (Ar = 2,6‐Me2C6H3 L2 , 2,6‐Et2C6H3 L3 , 2,6‐i‐Pr2C6H3 L4 , 2,4,6‐Me3C6H2 L5 , 2,6‐Et2‐4‐MeC6H2 L6 ), incorporating at least one N ?2,4‐bis(difluoro benzhydryl)‐6‐methylphenyl group, have been synthesized and fully characterized. Interaction of L1 – L6 with (DME)NiBr2 (DME = 1,2‐dimethoxyethane) generates the corresponding nickel(II) bromide N,N‐chelates, L NiBr2 ( 1 – 6 ), in high yield. The molecular structures of 3 and 6 reveal distorted tetrahedral geometries at nickel with the ortho‐substituted difluorobenzhydryl group providing enhanced steric protection to only one side of the metal center. On activation with various aluminum alkyl co‐catalysts, such as methylaluminoxane (MAO) or Et2AlCl, 1 – 6 displayed outstanding activity toward ethylene polymerization (up to 1.02 × 107 g of PE (mol of Ni)?1 h?1). Notably 1 , bearing equivalent fluorobenzhydryl‐substituted N‐aryl groups, was able in the presence of Et2AlCl to couple high activity with exceptional thermal stability generating high molecular weight branched polyethylenes at temperatures as high as 100 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1971–1983 |
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Keywords: | branched cationic polymerization nickel complex polyethylene thermal properties |
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