The N-formylation reaction of various amines with CO₂ is a promising method to utilize CO₂ for the production of high value-added chemicals. Herein, an efficient Ru catalyst system consisting of Ru complex ([PPN][Ru(CO)₃Cl₃]) and the ionic liquid 1-butyl-3-methylimidazolium hydrogen phosphate ([Bmim]₂[HPO₄]), has been developed for the N-formylation reaction. Activity evaluation demonstrated that the catalyst system exhibited good to excellent yields of formamides under very mild conditions with the assistance of ionic liquids (ILs). Furthermore, the catalyst system could be reused at least five times with a slight loss of activity in N-formylmorpholine production. Further characterization by ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and density functional theory (DFT) calculations showed that the ILs ([Bmim]₂[HPO₄]) could facilitate the adsorption of CO₂ by a concerted action of both cations and anions of the ILs to form phosphorus carbonate intermediate, thus effectively promoting the reaction. DFT calculations demonstrated that the formation of Ru–H was the first step, and then the CO₂ absorbed by [Bmim]₂[HPO₄] inserted directly into Ru–H by cooperating with the Ru sites to form HCOO^– species. After that, formate species dissociated from Ru catalysts and dehydrated to form formamides by the catalytic action of Ru complex and the basic IL.

中文翻译：

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离子液体辅助的钌配合物催化二氧化碳和氢对胺的N-甲酰化

各种胺与CO ₂的N-甲酰化反应是利用CO ₂生产高附加值化学品的一种很有前景的方法。在此，一种高效的 Ru 催化剂体系由 Ru 络合物 ([PPN][Ru(CO) ₃ Cl ₃ ]) 和离子液体 1-丁基-3-甲基咪唑鎓磷酸氢盐 ([Bmim] ₂ [HPO ₄])，已开发用于 N-甲酰化反应。活性评估表明，在离子液体 (IL) 的帮助下，该催化剂体系在非常温和的条件下表现出良好至极好的甲酰胺产率。此外，该催化剂体系可以重复使用至少五次，N-甲酰基吗啉生产中的活性略有下降。通过¹ H 核磁共振 (NMR)、¹³ C NMR 和密度泛函理论 (DFT) 计算的进一步表征表明，ILs ([Bmim] ₂ [HPO ₄ ]) 可以促进 CO ₂的吸附通过离子液体的阳离子和阴离子的协同作用形成碳酸磷中间体，从而有效地促进反应。DFT 计算表明，Ru-H 的形成是第一步，然后[Bmim] ₂ [HPO ₄ ]吸收的 CO ₂通过与 Ru 位点合作形成 HCOO ^-物种直接插入 Ru-H 。之后，甲酸盐物质从 Ru 催化剂上解离并在 Ru 络合物和碱性 IL 的催化作用下脱水形成甲酰胺。