Aliphatic polyketones are produced via metal-catalyzed copolymerization of carbon monoxide (CO) and olefins. The product is usually the alternating copolymer. Only two types of Pd complexes can produce the non-alternating copolymer.<br/>Several zwitterionic nickel(II) compounds with anionic diphosphine ligands have been synthesized and studied as the catalysts for CO-ethylene copolymerization in Jia’s lab. This presentation discusses the ligand and solvent effects on the catalysts’ activity and lifetime. The catalyst’s lifetime and overall productivity have been markedly improved by the presence of the <i>o</i>-methoxy ancillary on the phenyl group of the ligand. A certain degree of steric hindrance around the Ni(II) center is found necessary to achieve high polymerization activity. THF improves both the activity and productivity of the catalysts. The polyketones produced with these zwitterionic Ni(II) catalysts, however, are still strictly alternating copolymer.<br/>New development of the ligand’s framework will be discussed that has greatly changed the catalyst behavior for the CO-ethylene copolymerization. The polyethylene with a little in chain keto group and polyketone with extra ethylene insertion were both made with this zwitterionic Ni(II) complex under different polymerization conditions

Zwitterionic nickel (II) catalysts for CO-ethylene copolymerization

ACS Spring 2022

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