Implications of CO2 Activation by Frustrated Lewis Pairs in the Catalytic Hydroboration of CO2: A View Using N/Si+ Frustrated Lewis Pairs

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• 作者：N. von Wolff ; G. Lefèvre ; J.-C. Berthet ; P. Thuéry ; T. Cantat
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：July 1, 2016
• 年：2016
• 卷：6
• 期：7
• 页码：4526-4535
• 全文大小：632K
• 年卷期：0
• ISSN：2155-5435

文摘

A series of base-stabilized silylium species were synthesized and their reactivity toward CO₂ explored, yielding the characterization of a novel N/Si⁺ FLP-CO₂ adduct. These silicon species are active catalysts in the hydroboration of CO₂ to the methoxide level with 9-BBN, catecholborane (catBH), and pinacolborane (pinBH). Both experiments and DFT calculations highlight the role of the FLP-CO₂ adduct in the catalysis. Depending on the nature of the hydroborane reductant, two distinct mechanisms have been unveiled. While 9-BBN and catBH are able to reduce an intermediate FLP-CO₂ adduct, the hydroboration of CO₂ with pinBH follows a different and novel path where the B–H bond is activated by the silicon-based Lewis acid catalyst. In these mechanisms, the formation of a highly stabilized FLP-CO₂ adduct is found detrimental to the kinetics of the reaction.