Nickel Alkyl Complexes for Polymerization Catalysis via Oxidative Addition–Decarbonylation of Phosphinephenol Esters

Phosphinephenol esters react with Ni 0 to afford otherwise difficult to access Ni II –alkyl complexes. The reaction proceeds efficiently and cleanly by coordination of phosphine to the Ni 0, which directs an intramolecular oxidative addition into the C(acyl)–O bond followed by rapid carbon monoxide elimination. The potential of this mild preparative pathway was demonstrated by the synthesis of a higher Ni II – n -alkyl complex, and of a five-membered chelate that is the key intermediate in the nonalternating copolymerization of ethylene and carbon monoxide, as well as its 13 C-labeled analog. Further, the title reaction can regenerate active polymerization catalyst after CO-induced deactivation under pressure reactor conditions, highlighting its broader utility. This shows the directed oxidative addition-decarbonylation of phenolesters provides a broad platform to access catalytically relevant Ni alkyl complexes.