Chinese Journal of Applied Chemistry ›› 2015, Vol. 32 ›› Issue (8): 909-915.DOI: 10.11944/j.issn.1000-0518.2015.08.140425

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Pyrazolylimine Ni(Ⅱ) Complexes: Synthesis, Characterization, and Catalytic Behaviors for 1, 3-Butadiene Polymerization

HAN Chaoa,LIU Hengb,YANG Fenga*(),HU Yanmingb,ZHANG Xuequanb*   

  1. a School of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142, China
    b Key Laboratory of Synthetic Rubber, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
  • Received:2014-12-12 Accepted:2015-04-02 Published:2015-08-08 Online:2015-08-08
  • Contact: YANG Feng,ZHANG Xuequan
  • Supported by:
    Supported by National Natural Science Foundation of China(No.51203092)

Abstract:

A series of NN-bidentate nickel(Ⅱ) complexes bearing pyrazolylimine ligands(4a~4e) was synthesized and characterized by FTIR and elemental analysis. Determined by X-ray single crystal diffraction, complex 4b adopted distorted trigonal bipyramidal geometry around the central metal. Activated by ethylaluminum sesquichloride(EASC), all complexes exhibited high cis-1, 4 selectivity towards 1, 3-butadiene polymerization to afford liquid polybutadienes(PB) with relative molecular mass of 4500~9000 and 91% cis-1, 4 content. The catalytic activity of the complex decreased as the hindrance of the substituent on the ligand increased. The effects of Al/Ni molar ratio and polymerization temperature on the polymerization were further investigated in details. The catalytic activity increased with the increase of polymerization temperature from 20 ℃ to 60 ℃, and the polymer yield only slightly decreased even at a high temperature of 80 ℃, indicating high thermal stability of the active species generated by the present catalytic system.

 

Key words: pyrazolylimine, nickle complex, liquid polybutadiene, coordination polymerization

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