Effect of Sodium Cation on Metallacycle β‐Hydride Elimination in CO2–Ethylene Coupling to Acrylates |
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Authors: | Dong Jin Prof Paul G Williard Prof Nilay Hazari Prof Wesley H Bernskoetter |
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Institution: | 1. Department of Chemistry, Brown University, Providence, RI 02912 (USA);2. Department of Chemistry, Yale University, New Haven, CT 06520 (USA) |
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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. |
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Keywords: | density functional calculations fixation of carbon dioxide metallacycles nickel |
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