Synthesis,characterization and ethylene polymerization of 1-(2,6-dimethyl-4-fluorenylphenylimino)-2-aryliminoacenaphthylnickel bromides |
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Affiliation: | 1. Key Laboratory of Engineering Plastics, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China;2. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China |
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Abstract: | A series of 1-(2,6-dimethyl-4-fluorenylphenylimino)-2-aryliminoacenaphthylene compounds (aryl = 2,6-di(Me)Ph (L1), 2,6-di(Et)Ph (L2), 2,6-di(i-Pr)Ph (L3), 2,4,6-tri(Me)Ph (L4), 2,6-di(Et)-4-MePh (L5)) was prepared and used to form their corresponding dibromonickel complexes (D1–D5). Both L1–L5 and D1–D5 were fully characterized by FT-IR and elemental analysis as well as NMR measurements in the case of ligands L1–L5. The molecular structure of the representative complex D5 was confirmed by single crystal X-ray diffraction revealing a distorted trigonal bipyramidal geometry around the nickel center. On activation with either ethylaluminium sesquichloride (Et3Al2Cl3, EASC) or methylaluminoxane (MAO), all nickel complexes exhibited high activities up to 9.82 × 106 g of PE (mol of Ni)−1 h−1 for ethylene polymerization. In comparison with the polyethylenes obtained with related Ni pre-catalysts, the polyethylenes obtained in this work possessed relatively higher molecular weights and lower levels of branching, highlighting the significant influence of the remote fluorenyl substituent. |
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Keywords: | Acenaphthylene ligand Ni(II) complex Ethylene polymerization Lesser branched polyethylene |
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