1,3-Butadiene Polymerizations Catalyzed by Cobalt and Iron Dichloride Complexes Bearing Pyrazolylimine Ligands

  • Liang Fang
  • Wen-Peng Zhao
  • Chao Han
  • Chun-Yu ZhangEmail author
  • Heng LiuEmail author
  • Yan-Ming Hu
  • Xue-Quan Zhang


A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of (PhC=N(C6H3(R1)2-2,6)(C3HN2 (R2)2-3,5)MtCl2 (R1 = Me, R2 = H, Mt = Co (1a), Fe (2a); R1 = Me, R2 = Me, Mt = Co (1b), Fe (2b); R1 = iPr, R2 = H, Mt = Co (1c), Fe (2c); R1 = iPr, R2 = Me, Mt = Co (1d), Fe (2d); R1 = iPr, R2 = Ph, Mt = Co (1e), Fe (2e)) were synthesized and thoroughly characterized. Determined by single crystal X-ray diffraction, complexes 1b and 2b revealed dimeric structures, in which distorted trigonal bipyramid geometries were adopted for each metal centers. In the presence of ethylaluminum sesquichloride (EASC), all the cobalt complexes displayed high activities in 1,3-butadiene polymerization, affording polybutadienes with predominant cis-1,4 contents (up to 97.0%). Influences of ligand structure and polymerization parameters on catalytic performance were investigated systematically. For pyrazolylimine iron(II) dichloride complexes, the catalytic activities and microstructures of the resultant polybutadienes were highly dependent on ligand structures and polymerization conditions. For complex 2a, changing cocatalyst from trialkyl aluminums to methyl aluminoxane (MAO) led to an shift of selectivity from high cis-1,4- to trans-1,4-/1,2- manner. Being activated by MAO, complexes 2a and 2b gave trans-1,4-/1,2- binary polybutadienes, while complexes 2c, 2d, and 2e afforded cis-1,4- enriched polymers.


Late transition metal Cobalt(II) complexes Iron(II)complexes Stereoselective polymerization Polybutadiene 


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This work was financially supported by the National Basic Research Program of China (No. 2015CB654700 (2015CB654702)) and the National Natural Science Foundation of China (No. 21801236).


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Copyright information

© Chinese Chemical Society, Institute of Chemistry (CAS) and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.CAS Key Laboratory of High-Performance Synthetic Rubber and its Composite Materials, Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchunChina
  2. 2.University of Chinese Academy of SciencesBeijingChina
  3. 3.School of Materials Science and EngineeringShenyang University of Chemical TechnologyShenyangChina

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