Ortho-Functionalized Dibenzhydryl Substituents in α-Diimine Pd Catalyzed Ethylene Polymerization and Copolymerization

Abstract

Sterically bulky diarylmethyl-based ligands have received increasing attention in the field of late-transition-metal catalyzed olefin polymerization. Ortho-substituents may have a significant impact on the performance of diarylmethyl-based α-diimine Pd catalysts. In this contribution, a series of α-diimine Pd catalysts bearing ortho-methoxyl/hydroxyl functionalized dibenzhydryl units were prepared, characterized, and investigated in ethylene polymerization and copolymerization with methyl acrylate (MA). The catalytic performances were improved by introducing more ortho-substituents. The catalysts exhibited good thermal stabilities at high temperatures, producing branched polyethylenes. The catalysts bearing hydroxyl groups possessing intramolecular H-bonding, resulted in slightly higher incorporation ratios of MA unit when compared with the catalysts bearing methoxyl groups.

Positional Electronic Effects in Iminopyridine‐N‐oxide Nickel Catalyzed Ethylene Polymerization†

“…[ 52 ] Interestingly, the nickel complexes bearing nitro substituents ( Ni NO , Ni ON , Ni HN , and Ni NN ) resulted in high catalytic activities and produced very high molecular weight polyethylene products (Table 1, entries 11—30), indicating the beneficial effects of the nitro group [ 46‐51 ] and the diarylmethyl moiety. [ 45,52‐54 ]…”

Ethylene homo and co‐polymerization catalyzed by extensively bulky nickel catalysts with shielding wings of chlorine atoms

“…Imine based late‐transition metal catalysts have a distinctive status in ethylene home and co‐polymerization 1–3 . A range of ligands such as, α ‐diimine, 4–10 salicylaldimines, 11–18 imino‐pyridyl, 19–25 keto‐imine, 26,27 iminopyridine‐ N ‐oxide, 28,29 pyrrole‐imines 30 and pyrazolyl‐imines 31–33 have been synthesized by simple condensation method. A literature survey revealed that, any structural modification either in the amines or carbonyl containing backbone has characteristic influence not only on the catalyst performance but also on the polymer properties such as, molecular weight and microstructure 34–43 .…”

Fluorine Effect on α-Imino-ketone- and Phenoxyiminato Nickel-Catalyzed Ethylene Homo- and Copolymerization

“…Palladium has been long considered as the most suitable element for ethylene copolymerization with polar comonomers. − Its importance was recognized after the remarkable incorporation of methyl acrylate into the polyolefin backbone using Brookhart-type α-diimine catalysts. , Despite the leading status of palladium, nickel also plays an influential role in this race. Recently, both industrial and academic researchers have commenced to appreciate the elusive differences and benefits that nickel can offer compared to palladium due to its low cost and the capability to produce polymers with high molecular weight. − In this scenario, a range of ligands have been explored such as N^N-type, − N^O-type, − and P^O-type − ligands.…”