Wu Ruiyao, Niu Zhen, Huang Lingyun, Yang Yinxin, Xia Zhu, Fan Weifeng, Dai Quanquan, Cui Long, He Jianyun, Bai Chenxi
Key Laboratory of High-Performance Synthetic Rubber and Its Composite Materials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.
University of Science and Technology of China, 230026, Hefei, Anhui, China.
Dalton Trans. 2021 Nov 16;50(44):16067-16075. doi: 10.1039/d1dt03004c.
In this work, a series of oxovanadium complexes bearing the ligands (,)-(+)-2, 6-dialkyl--(2-((2-(4-isopropyl-4,5-dihydrooxazole-2-yl)phenyl)amino)benzylidene)aniline (dialkyl = dimethyl (V1), diethyl (V2), and isopropyl (V3)) have been synthesized and characterized by FTIR spectroscopy and elemental analysis. Moreover, the molecular structures of complexes V2 and V3 were defined by X-ray diffraction. On activation with ethylaluminium sesquichloride (AlEtCl), these complexes exhibited high activity towards ethylene polymerization (up to 1.39 × 10 g mol h) and showed excellent thermal stability (up to 60 °C). The obtained polyethylene had a moderate molecular weight (21.9 × 10 to 66.4 × 10 g mol) and exhibited narrow distribution (1.91 to 2.86) and unimodal features. The effect of the substituents on the ligands was also investigated in detail. The compound bearing the diisopropyl group showed the highest activity toward ethylene polymerization as the bimolecular deactivation of the catalyst can be effectively inhibited by the steric hindrance of the -substituent on aniline. The complex V2 with moderate steric hindrance was also evaluated as a catalyst for the copolymerization of ethylene with norbornene and showed moderate to high activity.
