Influence of Backbone Substituents on the Ethylene (Co)polymerization Properties of α-diimine Pd(II) and Ni(II) Catalysts

Abstract

A series of α-diimine ligands with different substituents on the acenaphthyl backbone were synthesized and characterized. The corresponding Ni(II) and Pd(II) complexes were prepared and used in ethylene polymerization and copolymerization with methyl acrylate. In ethylene polymerization, these Ni(II) complexes showed activities of up to 1.6 × 10 7 g/((mol of Ni) h), generating polyethylene with a molecular weight (M n ) of up to 4.2 × 10 5 . Interestingly, these Ni(II) complexes behave very similarly in ethylene polymerization except for the complex with two methoxy substituents on the ortho position of the acenaphthyl backbone, in which case about 3 times higher polyethylene molecular weight and much lower branching density were observed. The ligand substituent effect is much more dramatic for the Pd(II) complexes. In ethylene polymerization, activities of up to 1.7 × 10 5 g/((mol of Pd) h) and a polyethylene molecular weight (M n ) of up to 4.7 × 10 4 could be obtained. The Pd(II) complex with two methoxy substituents on the ortho position of the acenaphthyl backbone demonstrated much higher activity and generated polyethylene with about 3 times higher molecular weight than that for the classic Pd(II) complex. A similar trend was maintained in ethylene−methyl acrylate copolymerization.

Lysosome‐targeted potent half‐sandwich iridium(III) α‐diimine antitumor complexes

“…Due to the excellent chemical properties of N,N‐chelating ligands and their pharmaceutical chemistry, especially in materials science as mesoporous materials and liquid crystals, they have been investigated for their antitumor activity. Especially, as with other metal coordination, nitrogen‐donor ligands based upon the α‐diimine moiety have a wide range of applications in high‐performance catalytic and synthetic chemistry . Although α‐diimine has many excellent properties, to the best of our knowledge, diimine‐based organometallic iridium complexes used as antitumor agents have not been explored.…”

Simple Preparation of Halogen-Substituted <i>α</i>-Diimine Nickel Complexes Immobilized into Clay Interlayer as Catalysts for Ethylene Oligo-/Polymerization

“…The charge control of the metal center in the complex could be achieved by introducing electro-donating groups or electro-withdrawing groups [17] [18] [19]. Modification of the ligand backbone structure is also known to be an important parameter in the catalyst design [20] [21] [22].…”

Cationic para‐phenyl‐substituted α‐diimine nickel catalyzed ethylene and 4‐methyl‐1‐pentene (co)polymerizations via living/controlled chain‐walking

“…The Brookhart‐type α‐ diimine based nickel and palladium catalyzed olefin polymerization reactions have received ever‐increasing attention during the past two decades due to the controlled chain ‐ walking process . This chain‐walking mechanism offers great potentials for the control of polymer branched microstructures, through modifications of ligand structures as well as polymerization conditions containing reaction temperature, types and concentration of monomers, which are strongly affecting the different of the resulting polymers and copolymers . There are many studies for ethylene (E) and α‐ olefin polymerizations using nickel and palladium catalysts to produce polymers possessing different branched structures .…”