Monoarylmethyl Substituents Dictate Stability and Chain Transfer Behavior in Late Transition Metal Pyridine-Imine Catalytic Systems
Year: 2025
Type: article
Abstract: Pyridine-imine Ni(II) and Pd(II) catalysts are pivotal in ethylene polymerization and copolymerization, offering tunable ligand architectures for precise control over catalytic performance. This study explores flexible monoarylmethyl-substituted pyridine-imine Ni(II)/Pd(II) catalysts, demonstrating their efficacy in ethylene oligomerization and co-oligomerization with methyl acrylate (MA). The Ni(II) catalysts, activated by diethylaluminum chloride, exhibited high activity (up to 2.66 × 106 g/(mol Ni·h)) and produced highly branched ethylene oligomers (83–124 branches/1000C) with low molecular weights (844–2159 g/mol). Conversely, Pd(II) catalysts, activated by NaBArF, showed moderate activity (1.07–15.97 × 104 g/(mol Pd·h)) and generated ethylene oligomers with higher branching densities (64–163 branches/1000C). Notably, the Pd(II) systems achieved efficient MA incorporation (4.66–18.26 mol%) in co-oligomerization, yielding hyperbranched functionalized products. In comparison with classical ethyl nickel and palladium catalysts, the monoarylmethyl catalysts demonstrated higher polymerization activity and produced higher-molecular-weight ethylene oligomers. Furthermore, when compared to the previously reported rigid phenyl- and dibenzhydryl-nickel and palladium catalysts, the flexible benzyl catalysts in this work exhibited comparable polymerization activity while generating more highly branched ethylene oligomers. The steric and conformational flexibility of monoarylmethyl substituents were demonstrated to exert critical control over catalytic activity, chain transfer kinetics, and polar monomer incorporation efficiency, offering fundamental guidance for the rational design of advanced polyolefin materials.
Source: Organometallics
Authors: Mengya Ma, Shengyu Dai
Institutions: Anhui University, Anhui Normal University
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Award: G105391209
OpenAlex ID: W4414533809