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C–C bridged Ni(II) complexes bearing β‐keto‐9‐fluorenyliminato ligands prepared by different in situ bonding mechanisms and their use in catalytic (co)polymerization of norbornene and styrene
Author(s) -
He Xiaohui,
Wang Suli,
Yang Yingping,
Tu Guangshui,
Zhang Feng,
Huang Shengmei,
Duan Yapeng,
Zhu Chuanyi,
Cheng Changwen,
Chen Defu
Publication year - 2019
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.4694
Subject(s) - chemistry , norbornene , catalysis , styrene , polymerization , intramolecular force , polymer chemistry , addition polymer , thermal stability , trifluoromethyl , coupling reaction , copolymer , crystallography , stereochemistry , polymer , organic chemistry , alkyl
Two C–C bridged Ni(II) complexes bearing β‐keto‐9‐fluorenyliminato ligands with electron‐withdrawing groups (─CF 3 ), Ni{PhC(O)CHC[N(9‐fluorenyl)]CF 2 } 2 (Ni 1 ) and Ni{CF 3 C(O)CHC[N(9‐fluorenyl)]Ph} 2 (Ni 2 ), were synthesized by metal coordination reaction and different in situ bonding mechanisms. The C–C bridged bonds of Ni 1 were formed by in situ intramolecular trifluoromethyl and 9‐fluorenyl carbon–carbon cross‐coupling reaction and those of Ni 2 were formed by in situ intramolecular 9‐fluorenyl carbon–carbon radical coupling reaction mechanism. The obtained complexes were characterized using 1 H NMR spectroscopy and elemental analyses. The crystal and molecular structures of Ni 1 and Ni 2 with C–C bridged configuration were determined using X‐ray diffraction. Ni 1 and Ni 2 were used as catalysts for norbornene (NB) polymerization after activation with B(C 6 F 5 ) 3 and the catalytic activities reached 10 6 g polymer mol Ni −1 h −1 . The copolymerization of NB and styrene catalyzed by the Ni 1 /B(C 6 F 5 ) 3 system showed high activity (10 5 g polymer mol Ni −1 h −1 ) and the catalytic activities decreased with increasing feed content of styrene. All vinyl‐type copolymers exhibited high molecular weight (10 4 g mol −1 ), narrow molecular weight distribution ( M w / M n = 1.71–2.80), high styrene insertion ratios (11.13–50.81%) and high thermal stability ( T d > 380°C) and could be made into thin films with high transparency in the visible region (400–800 nm).