Catalysts Based on Late Transition Metals (LTM): A Second Generation of Single Site Catalysts in Designing New Diimine Ligands for Olefin Polymerization

Ziegler-Natta and metallocene catalysts play an important role in polyolefin industrial production but their intrinsic drawbacks specially in providing new architectures in polymer chains and tolerance against polar functional groups havestimulated a major shift of focus on developing new catalytic systems especially late transitionmetal (LTM) catalysts. Pd (II)/ Ni(II)–α-diimine complexes are a major group of LTM catalysts. In these systems, any changes in ligand structure or even polymerization parameters dramatically affect the catalyst performance and final properties of polymer. An exciting recent direction in the polyolefin field is the design of new ligands in order to improve the performance of LTM catalysts in the polymerization systems. Herein, the trends inresearch activities followed by pioneer companies in the field of second generation of single site catalysts and also the specifications of LTM catalysts based on diimine systems and the new designed ligands of this family have been reported.