Highly active ortho-phenyl substituted ¦Á-diimine Nickel(II) catalysts for ¡°chain walking polymerization¡± of ethylene: Synthesis of the nanosized dendritic polyethylene

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• 作者：Jianchao Yuan ; ^{jianchaoyuan@nwnu.edu.cn} ; Fuzhou Wang ; Bingnian Yuan ; Zong Jia ; Fengying Song ; Jing Li
• 关键词：Ni(II) complexes ; ¦Á-Diimine ligand ; Crystal structure ; Chain walking polymerization ; Dendritic polyethylene
• 刊名：Journal of Molecular Catalysis A: Chemical
• 出版年：2013
• 出版时间：April, 2013
• 年：2013
• 卷：370
• 期：Complete
• 页码：132-139
• 全文大小：617 K

文摘

Three new ¦Á-diimine Ni(II) complexes {bis[N,N¡ä-(4-fluoro-2,6-diphenylphenyl)imino]acenaphthene}dibromonickel 4a, {bis[N,N¡ä-(4-chloro-2,6-diphenylphenyl)imino]acenaphthene}dibromonickel 4b, and {bis[N,N¡ä-(4-methyl-2,6-diphenylphenyl)imino]acenaphthene}dibromonickel 4c, were synthesized and characterized. The crystal structure of the complex 4a was determined by X-ray crystallography. Complex 4a has pseudo-tetrahedral geometry about the nickel center, showing C_2v molecular symmetry. These complexes, activated by diethylaluminum chloride (DEAC) were tested in the polymerization of ethylene under mild conditions. Complex 4a bearing 2,6-diphenyl and strong electron-withdrawing 4-fluorine groups, activated by diethylaluminum chloride (DEAC) shows highly catalytic activity for the polymerization of ethylene [4.95 ¡Á 10⁶ g PE/(mol Ni h bar)] and produced dendritic polyethylene (153.3 branches/1000 C). The dendritic polyethylene particle size obtained by 4a/DEAC can be controlled in the 1-20 nm under 0.2 bar ethylene pressure, and could be expected to become a nano-targeted drug carrier after modified with water-soluble oligo(ethylene glycol) (OEG).