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Controlled isoprene polymerization mediated by iminopyridine‐iron (II) acetylacetonate pre‐catalysts
Author(s) -
Zhao Mengmeng,
Wang Liang,
Mahmood Qaiser,
Jing Chuyang,
Zhu Guangqian,
Zhang Xianhui,
Wang Xiaowu,
Wang Qinggang
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.4836
Subject(s) - chemistry , isoprene , polymerization , monomer , alkyl , polymer chemistry , aryl , octahedral molecular geometry , ligand (biochemistry) , catalysis , steric effects , crystal structure , medicinal chemistry , stereochemistry , crystallography , polymer , organic chemistry , copolymer , biochemistry , receptor
A ligand controlled stereoselective polymerization of isoprene has been developed. A series of (aryl/alkyl)‐iminopyridine iron (II) acetylacetonate complexes: (aryl = Ph Fe1 ; alkyl = CH 2 Ph Fe2 , CH (Ph) 2 Fe3 , CH (Me) 2 Fe4 , C (Me) 3 Fe5 , C (Me) 2 CH 2 C(Me) 3 Fe6 ), has been prepared in which steric and electronic substituents systematically modified to investigate their influences for isoprene polymerization. The molecular structure of representative complex Fe2 was confirmed by single crystal X‐ray diffraction and, revealed a distorted octahedral geometry at iron center. On treatment with methylaluminoxane (MAO), Fe1 – Fe6 displayed low ( Fe5 & Fe6 ) to high activities ( Fe1 – Fe4 ) with quantitative monomer conversion (>99%) for isoprene polymerization producing polyisoprene of high molecular weight (up to 2.0 × 10 5 g/mol) and unimodal molecular weight distribution (1.4–3.3). Specifically, complex Fe2 (alkyl = CH 2 Ph) displayed the highest activity of 7.0 × 10 6 g (mol of Fe) −1 h −1 with 85% conversion of monomer over run time of 10 min at 25 °C. While, Fe6 catalyzed polyisoprene possessed high content of trans ‐1,4 unit (up to 87%). Furthermore, the influence of the reaction parameters and the nature of the ligands on the catalytic activities and microstructural properties of the polymer were investigated in detail.