Cycloheptyl‐fused NNO‐ligands as electronically modifiable supports for M(II) (M = Co,Fe) chloride precatalysts; probing performance in ethylene oligo‐/polymerization |
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| Authors: | Chantsalnyam Bariashir Zheng Wang Shizhen Du Gregory A Solan Chuanbing Huang Tongling Liang Wen‐Hua Sun |
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| Affiliation: | 1. Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China;2. CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing, China;3. Department of Chemistry, University of Leicester, University Road, Leicester, United Kingdom;4. State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China |
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| Abstract: | The N,N,O‐cobalt(II), 2,3‐{C4H8C(NAr)}:5,6‐{C4H8C(O)}C5HN]CoCl2 (Ar = 2,6‐(CHPh2)2‐4‐MeC6H2 Co1 , 2,6‐(CHPh2)2‐4‐EtC6H2 Co2 , 2,6‐(CHPh2)2‐4‐ClC6H2 Co3 , 2,6‐(CHPh2)2‐4‐FC6H2 Co4 ) and N,N,O‐iron(II) complexes, 2,3‐{C4H8C(NAr)}:5,6‐{C4H8C(O)}C5HN]FeCl2 (Ar = 2,6‐(CHPh2)2‐4‐MeC6H2 Fe1 , 2,6‐(CHPh2)2‐4‐EtC6H2 Fe2 , 2,6‐(CHPh2)2‐4‐ClC6H2 Fe3 , 2,6‐(CHPh2)2‐4‐FC6H2 Fe4 ), each containing one sterically enhanced but electronically modifiable N‐2,6‐dibenzhydryl‐4‐R2‐phenyl group, have been prepared by a one‐pot template approach using α,α′‐dioxo‐2,3:5,6‐bis(pentamethylene)pyridine, the corresponding aniline along with the respective cobalt or iron salt in acetic acid. Distorted square pyramidal geometries are a feature of the molecular structures of Co1 – Co4 . Upon activation with MAO or MMAO, Co1 – Co4 show good activities (up to 2.2 × 105 g mol?1(Co) h?1) affording short chain oligomers (C4–C30) with good α‐olefin selectivity. By contrast, Fe1 – Fe4 , in the presence of MMAO, displayed moderate activities (up 10.9 × 104 g(PE) mol?1(Fe) h?1) for ethylene polymerization forming low‐molecular‐weight linear polymers (up to 13.0 kg mol?1) incorporating saturated n‐propyl and i‐butyl chain ends. For both cobalt and iron, the precatalysts incorporating the more electron withdrawing 4‐R2‐substituents Cl ( Co3 / Fe3 ), F ( Co4 / Fe4 )] deliver the best catalytic activities, while with cobalt, these types of substituents additionally broaden the oligomeric distribution. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3980–3989 |
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| Keywords: | α ‐imino‐α ′ ‐oxo‐2 3:5 6‐bis(pentamethylene)pyridine coordination polymerization metal‐organic catalysts oligomers polyethylene |
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