Controlling the ethylene polymerization parameters in iron pre-catalysts of the type 2-[1-(2,4-dibenzhydryl-6-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl] pyridyliron dichloride

• Published in: Polymer (Guilford) 2012-01, Vol.53 (1), p.130-137
• Main Authors: Zhao, Weizhen, Yu, Jiangang, Song, Shengju, Yang, Wenhong, Liu, Hao, Hao, Xiang, Redshaw, Carl, Sun, Wen-Hua
• Format: Article
• Language: English
• Subjects: Applied sciences; chemical structure; Diffraction; Ethylene; Ethylene polymerization; Exact sciences and technology; Iron; Iron pre-catalysts; Ligands; Linear polyethylene; molecular weight; Molecular weight distribution; Optimization; Organic polymers; Physicochemistry of polymers; polyethylene; Polyethylenes; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; pyridines; spectroscopy; X-ray diffraction
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2011.11.024

The ligand series 2-[1-(2,4-dibenzhydryl-6-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridines and the iron(II) chloride complexes thereof have been synthesized and characterized by elemental and spectroscopic analyses. The molecular structures of C1 and C2, determined by single-crystal X-ray diffraction analysis, confirmed a pseudo-square-pyramidal geometry at the iron center. Upon treatment with either MAO or MMAO, all iron pre-catalysts possessed good thermo-stability and exhibited high activities [up to 5.22×107gmol−1(Fe)h−1] toward ethylene polymerization, producing highly linear polyethylene products. Optimization of the reaction parameters gave polyethylenes with narrow molecular weight distributions, indicating that single-site active species were formed; the molecular weights of the resultant polyethylenes could also be controlled. [Display omitted]