Hyperbranched bisphosphinoamine ligands: synthesis, characterization and application in ethylene oligomerization

Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph 2 PCl) and CrCl 3 (THF) 3 as raw materials. The hyperbranched PNP ligands and chromium complexes were characte...

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Bibliographic Details
Published in:Journal of coordination chemistry 2017-08, Vol.70 (15), p.2708-2721
Main Authors: Wang, Jun, Zhang, Na, Shi, Weiguang, Shang, Yiteng, Li, Cuiqin
Format: Article
Language:English
Subjects:
1.0 G hyperbranched macromolecule
Catalysis
Catalytic activity
catalytic system
Chromium
Coordination compounds
Ethylene
ethylene oligomerization
Ligands
Macromolecules
NMR
Nuclear magnetic resonance
Oligomerization
PNP ligand
Raw materials
Selectivity
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Summary:Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph 2 PCl) and CrCl 3 (THF) 3 as raw materials. The hyperbranched PNP ligands and chromium complexes were characterized by FT-IR, 1 H NMR, 31 P NMR, UV and ESI-MS. Comparing with the chromium complexes, the hyperbranched PNP ligands, in combination with Cr(III), and activation by methylaluminoxane (MAO) in situ generated species with better catalytic performance for ethylene oligomerization. The effect of solvent, chromium source, ligand/Cr molar ratio, reaction temperature, Al/Cr molar ratio and reaction pressure on the catalytic activity and product selectivity were studied. The results showed that with increase of ligand/Cr molar ratio, reaction temperature and Al/Cr molar ratio, the catalytic activity increased at first and then decreased. However, the catalytic activity continuously increased with increase of reaction pressure. Under the optimized conditions, the catalytic system of hyperbranched PNP/Cr(III)/MAO led to catalytic activity of 2.68 × 10 5  g/(mol Cr·h) and 37.71% selectivity for C 6 and C 8 .
ISSN:0095-8972
1029-0389
DOI:10.1080/00958972.2017.1361531