Key Laboratory of High-Performance Synthetic Rubber and Its Composite Materials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, China.
School of Applied Chemistry and Engineering, University of Science and Technology of China, 230026 Hefei, Anhui, China.
Dalton Trans. 2023 Jun 27;52(25):8636-8644. doi: 10.1039/d3dt01065a.
Several trivalent and pentavalent vanadium complexes bearing 8-anilide-5,6,7-trihydroquinoline ligands were synthesized. These vanadium complexes were identified by elemental analysis, FTIR spectroscopy and NMR. Single crystals of trivalent vanadium complexes V2, V3', and V4 and pentavalent vanadium complexes V5 and V7 were further obtained and identified by X-ray single crystal diffraction. In addition, the catalytic performance of these catalysts was adjusted by controlling the electronic and steric effects of substituents in the ligands. In the presence of diethylaluminium chloride, complexes V5-V7 displayed high activity (up to 82.8 × 10 g mol h) and good thermal stability toward ethylene polymerization. In addition, the copolymerization ability of complexes V5-V7 was evaluated, and complexes V5-V7 displayed high activity (up to 105.6 × 10 g mol h) and high copolymerization ability toward ethylene/norbornene copolymerization. By adjusting the polymerization conditions, copolymers with norbornene insertion ratios of 8.1%-30.9% can be obtained. Complex V7 was further studied for ethylene/1-hexene copolymerization, and the obtained copolymer displayed a moderate 1-hexene insertion ratio of 1.2%. Complex V7 displayed high activity and high copolymerization ability while having thermal stability. The results showed that 8-anilide-5,6,7-trihydroquinoline ligands with fused rigid-flexible rings were beneficial for vanadium catalysts.
合成了几种带有 8-苯胺-5,6,7-三羟基喹啉配体的三价和五价钒配合物。这些钒配合物通过元素分析、傅里叶变换红外光谱和核磁共振进行了鉴定。进一步获得了三价钒配合物 V2、V3'和 V4 以及五价钒配合物 V5 和 V7 的单晶，并通过 X 射线单晶衍射进行了鉴定。此外，通过控制配体中取代基的电子和空间效应来调节这些催化剂的催化性能。在二乙基氯化铝存在下，配合物 V5-V7 对乙烯聚合表现出高活性（高达 82.8×10 g mol h）和良好的热稳定性。此外，还评估了配合物 V5-V7 的共聚能力，配合物 V5-V7 对乙烯/降冰片烯共聚表现出高活性（高达 105.6×10 g mol h）和高共聚能力。通过调整聚合条件，可以得到具有 8.1%-30.9%降冰片烯插入比的共聚物。进一步研究了配合物 V7 对乙烯/1-己烯共聚的催化性能，得到的共聚物 1-己烯的插入比为 1.2%。配合物 V7 具有高活性、高共聚能力和热稳定性。结果表明，带有稠合刚性-柔性环的 8-苯胺-5,6,7-三羟基喹啉配体有利于钒催化剂。
