Ethylene polymerization and ethylene/hexene copolymerization with vanadium(III) catalysts bearing heteroatom‐containing salicylaldiminato ligands

作者：Ji‐Qian Wu, Likun Pan, Sanrong Liu, Lipeng He, Yue‐Sheng Li · 发表于：Journal of Polymer Science Part A Polymer Chemistry · 年份：2009 · DOI：10.1002/pola.23441 · 被引用次数：37 · 研究领域：Organometallic Complex Synthesis and Catalysis、Carbon dioxide utilization in catalysis、Synthetic Organic Chemistry Methods

Abstract A series of novel vanadium(III) complexes bearing heteroatom‐containing group‐substituted salicylaldiminato ligands [RNCH(ArO)]VCl 2 (THF) 2 (Ar = C 6 H 4 , R = C 3 H 2 NS, 2a ; C 7 H 4 NS, 2c ; C 7 H 5 N 2 , 2d ; Ar = C 6 H 2 t Bu 2 (2,4), R = C 3 H 2 NS, 2b ) have been synthesized and characterized. Structure of complex 2c was further confirmed by X‐ray crystallographic analysis. The complexes were investigated as the catalysts for ethylene polymerization in the presence of Et 2 AlCl. Complexes 2a–d exhibited high catalytic activities (up to 22.8 kg polyethylene/mmol V h bar), and affording polymer with unimodal molecular weight distributions at 25–70 °C in the first 5‐min polymerization, whereas produced bimodal molecular weight distribution polymers at 70 °C when polymerization time prolonged to 30 min. The catalyst structure plays an important role in controlling the molecular weight and molecular weight distribution of the resultant polymers produced in 30 min polymerization. In addition, ethylene/hexene copolymerizations with catalysts 2a–d were also explored in the presence of Et 2 AlCl, which leads to the high molecular weight and unimodal distributions copolymers with high comonomer incorporation. Catalytic activity, comonomer incorporation, and polymer molecular weight can be controlled over a wide range by the variation of catalyst structure and the reaction parameters, such as comonomer feed concentration, polymerization time, and polymerization reactio...