2-[1-(2,6-Dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridyliron(II) dichlorides: Synthesis, characterization and ethylene polymerization behavior

A series of 2-[1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridine ligands (L1–L5) as well as the ligand 2,6-bis[1-(2,6-dibenzhydryl-4-chloro-phenylimino)ethyl]pyridine (L6) were synthesized and reacted with FeCl2·4H2O to afford the iron(II) dichloride complexes [LFeCl2] (F...

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Bibliographic Details
Published in:Polymer (Guilford) 2012-04, Vol.53 (9), p.1870-1880
Main Authors: Cao, Xiaoping, He, Fan, Zhao, Weizhen, Cai, Zhengguo, Hao, Xiang, Shiono, Takeshi, Redshaw, Carl, Sun, Wen-Hua
Format: Article
Language:English
Subjects:
Applied sciences
catalytic activity
chemical structure
ethylene
Ethylene polymerization
Exact sciences and technology
iron
Iron pre-catalysts
Linear polyethylene
Organic polymers
Physicochemistry of polymers
polyethylene
Polymerization
Preparation, kinetics, thermodynamics, mechanism and catalysts
pyridines
spectroscopy
thermal stability
X-ray diffraction
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Summary:A series of 2-[1-(2,6-dibenzhydryl-4-chlorophenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridine ligands (L1–L5) as well as the ligand 2,6-bis[1-(2,6-dibenzhydryl-4-chloro-phenylimino)ethyl]pyridine (L6) were synthesized and reacted with FeCl2·4H2O to afford the iron(II) dichloride complexes [LFeCl2] (Fe1–Fe6). All new compounds were fully characterized by elemental and spectroscopic analysis, and the molecular structures of the complexes Fe1, Fe2 and Fe4 were determined by single-crystal X-ray diffraction, which revealed a pseudo-square-pyramidal geometry at iron. Upon activation with either MAO or MMAO, all iron pre-catalysts exhibited very high activity in ethylene polymerization with good thermal stability. To the best of our knowledge, the current system showed the highest activity amongst iron bis(imino)pyridine pre-catalysts reported to-date. The polymerization parameters were explored to determine the optimum conditions for catalytic activity, which were typically found to be 2500 eq. Al to Fe at 60 °C in the presence of MMAO, and 80 °C in the presence of MAO. The resultant polyethylene possessed a narrow molecular polydispersity index (PDI) consistent with the formation of single-site active species. [Display omitted]
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2012.02.050