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Influence of imine‐ carbon substituent in 6‐bromo‐2‐iminopyridine‐based cobalt(II) complexes on 1,3‐butadiene polymerization
Author(s) -
Wang Feng,
Liu Heng,
Hu Yanming,
Zhang Xuequan
Publication year - 2019
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.5854
Subject(s) - substituent , methylaluminoxane , polymerization , imine , selectivity , chemistry , trigonal bipyramidal molecular geometry , cobalt , polymer chemistry , ligand (biochemistry) , crystallography , photochemistry , catalysis , stereochemistry , crystal structure , organic chemistry , polymer , metallocene , biochemistry , receptor
6‐Bromo‐2‐iminopyridine cobalt(II) complexes bearing different imine‐ carbon substituents ( Co1 – Co7 ) were synthesized and subsequently employed for 1,3‐butadiene polymerization. All the complexes were identified using Fourier transform infrared spectra and elemental analysis, and complexes Co1 and Co3 were further characterized using single‐crystal X‐ray diffraction analysis, demonstrating they adopted distorted trigonal bipyramidal and tetrahedral geometries, respectively. Activated by methylaluminoxane, these complexes exhibited high cis ‐1,4 selectivity, and the activity was highly dependent on the substituent at the imine‐ carbon position of the ligand. Addition of PPh 3 to the polymerization systems could enhance the catalytic activity and simultaneously switched the selectivity from cis ‐1,4 to cis ‐1,2 manner. On the basis of the obtained results, a plausible mechanism involving the regulation of selectivity and activity is proposed. © 2019 Society of Chemical Industry