Gao Zhihao, Tian Jiliang, Han Yingxia, Liu Shaofeng, Li Zhibo
Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.
Inorg Chem. 2024 Sep 30;63(39):18137-18145. doi: 10.1021/acs.inorgchem.4c02906. Epub 2024 Sep 17.
The pursuit of high-performance catalysts in the realm of polyolefins is a constant goal. In this study, a range of zirconium (, , , ) and hafnium (, ) complexes featuring phenoxy-imine-amine ONN-ligands (2,6-R-CH-NH-CH-N═CH-CH-3,5-Bu-OH; : R = H; : R = F; : R = Pr) were synthesized and characterized using NMR spectroscopy, as well as single-crystal X-ray diffraction for , , and . These Zr and Hf complexes exhibited remarkable efficiency for ethylene homopolymerization and copolymerization with 1-octene when paired with MAO as the cocatalyst. Notably, the Zr complexes outperformed the Hf complexes with the same ligand, underscoring the substantial impact of the metal center on catalytic performance. The substituents and coordination modes of the ligands also exerted significant influence on the catalytic behavior, affecting both the activity and properties of the resulting polymers. Particularly noteworthy was the exceptional activity of , achieving activity as high as 6.30 × 10 g(PE)·mol(Zr)·h for ethylene homopolymerization and generating bi- or multimodal distribution polyethylene. The activation of by 5 or 20 equiv of -MAO afforded a dinuclear Zr complex bridged by two chlorides (), which was analyzed and confirmed by H NMR spectroscopy and single-crystal X-ray diffraction.
在聚烯烃领域追求高性能催化剂是一个永恒的目标。在本研究中，合成了一系列具有苯氧基 - 亚胺 - 胺ONN - 配体（2,6 - R - CH - NH - CH - N═CH - CH - 3,5 - Bu - OH；：R = H；：R = F；：R = Pr）的锆（，，，）和铪（，）配合物，并使用核磁共振光谱以及对、和进行单晶X射线衍射进行表征。当与MAO作为助催化剂配对时，这些Zr和Hf配合物在乙烯均聚和与1 - 辛烯共聚方面表现出显著的效率。值得注意的是，具有相同配体的Zr配合物优于Hf配合物，突出了金属中心对催化性能的重大影响。配体的取代基和配位模式也对催化行为产生了重大影响，影响了所得聚合物的活性和性能。特别值得注意的是的卓越活性，在乙烯均聚中实现了高达6.30×10 g(PE)·mol(Zr)·h的活性，并生成双峰或多峰分布的聚乙烯。用5或20当量的 - MAO对进行活化得到了由两个氯桥连的双核Zr配合物（），通过 H NMR光谱和单晶X射线衍射对其进行了分析和确认。
