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Synthesis, characterization and 1,3‐butadiene polymerization behaviors of cobalt complexes bearing 2‐pyrazolyl‐substituted 1,10‐phenanthroline ligands
Author(s) -
Wang Baolin,
Gong Dirong,
Bi Jifu,
Dai Quanquan,
Zhang Chunyu,
Hu Yanming,
Zhang Xuequan,
Jiang Liansheng
Publication year - 2013
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.2972
Subject(s) - substituent , chemistry , cobalt , methylaluminoxane , polymerization , ligand (biochemistry) , phenanthroline , polymer chemistry , stereochemistry , crystallography , medicinal chemistry , inorganic chemistry , organic chemistry , metallocene , polymer , biochemistry , receptor
A series of cobalt(II) complexes containing tridentate 2‐pyrazolyl‐substituted 1,10‐phenanthroline ligands (L) with the general formula [LCoCl 2 ] have been successfully synthesized and fully identified by IR spectroscopy, elemental analysis and mass spectroscopy. Cobalt complexes Co4–Co8 were further confirmed by X‐ray crystallographic analysis, and all the complexes adopted distorted trigonal pyramid geometries around the cobalt center. In combination with methylaluminoxane, the complexes exhibit high cis ‐1,4‐selectivity for 1,3‐butadiene polymerization . The catalytic activities of the complexes mainly depend on the nature of the substituent and its position at the pyrazolyl ring of the ligand. Complexes having a bulkier substituent on the pyrazolyl ring of the ligand show lower catalytic activity and the incorporation of electron‐withdrawing substituent enhances the activity. Polymerization behaviors were almost not affected with varying [Al]/[Co] ratio, but both activity and the cis ‐1,4 content decrease slightly as polymerization temperature increasing. Copyright © 2013 John Wiley & Sons, Ltd.