title: Effect of sodium cation on metallacycle β-hydride elimination in CO2-ethylene coupling to acrylates.
abstract: The catalytic conversion of carbon dioxide and olefins into acrylates has been a long standing target, because society attempts to synthesize commodity chemicals in a more economical and sustainable fashion. Although nickel complexes have been known to successfully couple CO2 and ethylene for decades, a key β-hydride elimination step has proven a major obstacle to the development of a catalytic process. Recent studies have shown that Lewis acid additives can be used to create a lower-energy pathway for β-hydride elimination and facilitate a low number of catalytic turnovers. However, the exact manner, in which the Lewis acid promotes β-hydride elimination remains to be elucidated. Herein, we describe the kinetic and thermodynamic role that commercially relevant and weakly Lewis acidic sodium salts play in promoting β-hydride elimination from nickelalactones synthesized from CO2 and ethylene. This process is compared to a non-Lewis acid promoted pathway, and DFT calculations were used to identify differences between the two systems. The sodium-free isomerization reaction gave a rare CO2 -derived β-nickelalactone complex, which was structurally characterized.
authors: Department of Chemistry, Brown University, Providence, RI 02912 (USA).
authors: Dong
authors: D
authors: Jin
authors: Paul G
authors: PG
authors: Williard
authors: Nilay
authors: N
authors: Hazari
authors: Wesley H
authors: WH
authors: Bernskoetter
keywords: density functional calculations; fixation of carbon dioxide; metallacycles; nickel