李志波

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Development of Group IV Metal Complexes Bearing Thioether-Amido Ligands with Enhanced High-Temperature Catalytic Performance toward Olefin Copolymerization

发布时间:2024-12-24 点击次数:

关键字:CONSTRAINED-GEOMETRY COMPLEXES; POLYOLEFIN ELASTOMERS; TRIDENTATE LIGANDS; CHAIN WALKING; ETHYLENE; POLYMERIZATION
摘要:The development of homogeneous metal catalysts with both high activity and exceptional thermal stability is crucial for the efficient synthesis of polyolefin elastomers (POEs) through solution-phase olefin polymerization. In this study, a series of Hf (Hf1-Hf5), Zr (Zr1), and Ti (Ti1) complexes featuring thioether-amido ligands were synthesized and carefully characterized using advanced techniques such as H-1 and C-13 NMR spectroscopy as well as single-crystal X-ray diffraction analysis for Hf4 and Hf5. The results revealed that the catalytic activity and 1-octene incorporation efficiency of these metal complexes followed the trend Hf > Zr > Ti, underscoring the significant impact of the metal center on catalytic performance. Furthermore, the choice of ligands was found to play a critical role in dictating the catalytic properties, with ligands bearing less steric hindrance on the sulfur atom proving to be more favorable for copolymerization reactions. Notably, the Hf complex Hf1, featuring a methyl group on the sulfur atom, displayed exceptional catalytic activity as high as 21,060 kg(polymer)<middle dot>mol(-1)(Hf)<middle dot>h(-1) toward ethylene/1-octene copolymerization at 120 degrees C and produced POE with a high molecular weight (M-w = 6.3 x 10(4) g<middle dot>mol(-1)), relatively narrow distribution (& Dstrok; = 2.4), and high incorporation of 1-octene (34.1 mol %). This study demonstrates the potential of tailored ligand design in developing efficient metal catalysts for the production of high-value-added POEs.
卷号:63
期号:42
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