Raising the N-aryl fluoride content in unsymmetrical diaryliminoacenaphthylenes as a route to highly active nickel(ii) catalysts in ethylene polymerization

Xinxin Wang; Linlin Fan; Yichun Yuan; Shizhen Du; Yang Sun; Gregory A Solan; Cun-Yue Guo; Wen-Hua Sun

doi:10.1039/c6dt03817d

Raising the N-aryl fluoride content in unsymmetrical diaryliminoacenaphthylenes as a route to highly active nickel(ii) catalysts in ethylene polymerization

Dalton Trans. 2016 Nov 15;45(45):18313-18323. doi: 10.1039/c6dt03817d.

Authors

Xinxin Wang¹, Linlin Fan¹, Yichun Yuan², Shizhen Du², Yang Sun², Gregory A Solan³, Cun-Yue Guo⁴, Wen-Hua Sun¹

Affiliations

¹ 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.
² 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.
³ 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.
⁴ School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China. cyguo@ucas.ac.cn.

PMID: 27805197
DOI: 10.1039/c6dt03817d

Abstract

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). Both ¹H and ¹⁹F 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 × 10⁷ g 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 using ¹⁹F NMR spectroscopy.