Raising the N-aryl fluoride content in unsymmetrical diaryliminoacenaphthylenes as a route to highly active nickel(ii) catalysts in ethylene polymerization.
Five examples of selectively fluorinated unsymmetrical diiminoacenaphthylenes, 1-[2,6-{(4-FC6H4)2CH}2-4-FC6H4N]-2-(ArN) C2C10H6(Ar = 2,6-Me2C6H3L1, 2,6-Et2C6H3L2, 2,6-iPr2C6H3L3, 2,4,6-Me3C6H2L4, 2,6-Et2-4-MeC6H2L5), have been synthesized and used to prepare their corresponding nickel(ii) halide complexes, LNiBr2(Ni1-Ni5) and LNiCl2(Ni6-Ni10). Both1H and19F NMR spectroscopy techniques have been employed to characterize paramagnetic Ni1-Ni10; an inequivalent fluorine environment is a feature of the tetrahedral complexes in solution. Upon activation with relatively low ratios (ca. 600 equiv.) of ethylaluminum sesquichloride (Et3Al2Cl2, EASC), all the nickel complexes displayed high activities toward ethylene polymerization at 30 °C with precatalyst Ni4 the standout performer at 2.20 × 107g of PE per mol of Ni per h, producing highly branched polyethylenes. In comparison with related diiminoacenaphthylene-nickel catalysts, these current systems, incorporating a high fluorine content on one N-aryl group, display superior productivity. In addition, the molecular structures of Ni2 and Ni4 are reported and the active catalyst is probed using19F NMR spectroscopy.
School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China. cyguo@ucas.ac.cn and Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn.
Xinxin
X
Wang
School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China. cyguo@ucas.ac.cn and Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn.
Linlin
L
Fan
Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn.
Yichun
Y
Yuan
Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn.
Shizhen
S
Du
Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn.
Yang
Y
Sun
Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn and Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK. gas8@leicester.ac.uk.
Gregory A
GA
Solan
School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China. cyguo@ucas.ac.cn.
Cun-Yue
CY
Guo
School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China. cyguo@ucas.ac.cn and Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China. whsun@iccas.ac.cn.
Wen-Hua
http://orcid.org/0000-0002-6614-9284
WH
Sun