三齿配位钛配合物催化烯烃聚合

Tridentate Titanium Precatalysts Toward Olefin Polymerization

钛基聚烯烃催化剂不仅满足了价廉和性质优良的聚烯烃生产,而且有望进一步提升聚烯烃品质和发展新型聚烯烃树脂,因而结构可控钛配合物催化剂设计合成与催化性能提升是聚烯烃研究的核心课题之一。在茂金属催化剂之外,多齿配体的钛配合物成为研究的热点,其中,三齿配体良好地稳定了钛配合物。与此同时,配位原子的多样化极大地丰富了配合物合成与催化活性调控,在控制聚合活性的同时改善了所得聚合物的微观结构和宏观性能。本综述集中讨论了近年来在烯烃聚合催化体系中三齿配位钛配合物新研究的进展,讨论了取代基对于配合物中电子效应和立体效应的影响,以及配合物结构变化对于烯烃聚合活性及所得聚合物性能的影响关系,相关结果有助于指导钛配合物设计合成和催化聚合规律的研究。

Titanium-based catalysts have been not only providing major catalyses in conventionally producing massive polyolefins with lowcost as well as good properties,but also advancing the properties of newpolyolefins for newplastic materials.Therefore it has been a core consideration of finely tuning the structures of titanium complexes and enhancing catalytic performances of the olefin polymerization.Besides metallocene catalysts,titanium complexes bearing multi-dentate ligands have been maintained as hot topics,in which tridentate ligands positively stabilize titanium complexes.M eanwhile variations of coordination atoms of those ligands greatly enrich the syntheses and manipulation of the catalytic activity of complexes,therefore controlling the polymerization activity as well as improving the microstructures and properties of resultant polyolefin materials.Herein the recent progress of titanium complexes bearing tridentate ligands have been reviewed toward olefin polymerization,focusing on the electronic and steric influences of substituents within ligands on their catalytic activities and properties of resultant polyolefins.The observations would be helpful to design titanium complexes and correlations between activities of complexes and structures of ligands used.