Thermostable α-Diimine Nickel Complexes with Substituents on Acenaphthequinone-backbone for Ethylene Polymerization

• Published in: Chinese journal of polymer science Vol. 38; no. 11; pp. 1214 - 1220
• Main Authors: Zhang, Rui-Fang, Hou, Yan-Hui, Wei, Xu-Ling, Zhao, Ding-Ding, Cui, Mi-Mi, Zhai, Fei-Fan, Li, Xiang-Liu, Liu, Bin-Yuan, Yang, Min
• Format: Journal Article
• Language: English
• Published: Beijing Chinese Chemical Society and Institute of Chemistry, CAS 01.11.2020; Springer Nature B.V
• Subjects: Aromatic compounds; Backbone; Catalysts; Catalytic activity; Characterization and Evaluation of Materials; Chemical synthesis; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Coordination compounds; Diimide; Industrial Chemistry/Chemical Engineering; Nickel; Polyethylenes; Polymer Sciences; Polymerization; Thermal stability; Thermostability; Ethylene polymerization; Diimine nickel; Ligand backbone structure
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-020-2430-x

In order to promote the thermostability of α -diimine nickel complex by ligand backbone structure, a series of α -diimine nickel complexes with substituents on acenaphthequinone backbone were synthesized and used as catalysts for ethylene polymerization. When the hydroxyethyl phenoxyl group was introduced to the acenaphthequinone-backbone, the thermal stability and activity of the catalyst could be significantly improved. The catalytic activity of complex C2 [5-(4-(2-hydroxyethyl)phenoxyl)- N , N -bis(2,6-diisopropyl)acenaphthylene-1,2-diimine]nickel(II) dibromide with isopropyl substituents on N -aryl reached 8.2 × 10 6 g/(mol Ni ·h) at 70 °C and 2 MPa. The activity of [5-(4-(2-hydroxyethyl)phenoxyl)- N,N -bis(2,6-dibenzhydryl-4-menthylphenyl)acenaphthylene-1,2-diimine]nickel(II) dibromide ( C3 ) still maintained at 6.7 × 10 5 g/(mol Ni ·h) at 120 °C. Compared with C3 containing bulky dibenzhydryl substituents, the activity of C2 was sensitive to the change of the polymerization pressure. However, the polyethylenes obtained from complex C3 had lower branching density. Meanwhile, the molecular weight could reach 971 kg/mol, which is almost 5 times as much as that of the polyethylene obtained from complex C2 .