化学
甲基铝氧烷
共聚物
钛
共单体
乙烯
高分子化学
聚合
配体(生物化学)
亚苯基
结晶学
立体化学
催化作用
聚合物
茂金属
有机化学
生物化学
受体
作者
Jian Li,Liwei Wang,Yawen Qin,Qingliang You,Tingcheng Li,Lang Sun,Xiang‐Dan Li,Guangyong Xie
摘要
Binuclear complexes for olefin polymerization have attracted great attention due to their unique catalytic properties compared with their mononuclear counterparts. Here a series of p ‐phenylene‐bridgedbis‐β‐carbonylenamine ligands and their binuclear Ti complexes Ti 2 L 1 – Ti 2 L 3 were prepared and characterized by 1 H NMR, 13 C NMR, Fourier transform infrared spectroscopy, and elemental analysis. The binuclear complex Ti 2 L 3 bearing an octylthio sidearm was further investigated by single‐crystalX‐ray diffraction, which revealed that the ligand was of β‐imino enol form, with one titanium atom ligated with six other atoms, forming a deformed octahedral configuration. Furthermore, the ligand in Ti 2 L 3 adopted a cis configuration, which was different from the trans configuration of its m ‐phenylene‐bridged derivatives. These binuclear complexes ( Ti 2 L 1 – Ti 2 L 3 ) could catalyze ethylene polymerization and copolymerization with 1,5‐hexadiene(1,5‐HD) efficiently under modified methylaluminoxane activation. Compared with the mononuclear complex TiL 5 , the binuclear catalysts were thermally more stable and showed higher activity for ethylene polymerization at higher temperatures. The activity of these titanium complexes for the copolymerization of ethylene with 1,5‐HD were over 10 6 g/mol Ti.h.atm, almost twice as high as for homopolymerization. Compared with the mononuclear analogue TiL 5 and the m ‐substituted binuclear derivative Ti 2 L 4 , binuclear catalyst Ti 2 L 2 showed higher activity and insertion rate of the comonomer. The activity of Ti 2 L 2 was two to three times higher than that of TiL 5 and Ti 2 L 4 , indicating that p‐ substituted binuclear catalysts generate clear bimetallic synergistic effect for the copolymerization of ethylene and 1,5‐HD. Meanwhile, 1,5‐HD takes 1,3‐cyclopentyl form in the polymer by 1,3‐insertion. The copolymer prepared by binuclear catalysts had higher molecular weight and wider molecular weight distribution than that prepared by the mononuclear catalyst.
科研通智能强力驱动
Strongly Powered by AbleSci AI