N-heterocyclic carbenes (NHCs) are found to be efficient halogen-free organocatalysts for chemical conversion of CO₂, however, their inherent nature is sensitive to water and air, which leads to limitations in practical applications. In this work, we demonstrate the halogen- and metal-free methods for chemical fixation of CO₂ into valuable chemicals of cyclic carbonates and methylamines using air and water-stable organocatalysts of imidazolium hydrogen carbonate ionic liquids (C_nC_mImHCO₃). Good to excellent yields of cyclic carbonates and methylamines are obtained for varied substrates under mild conditions. Mechanism insight shows that the C_nC_mImHCO₃, as an organic pre-catalysts for N-heterocyclic carbene, can balance to carbene CO₂ adduct (C_nC_mIm-CO₂) serving as the active species for conversion of CO₂. As a result, the halogen- and metal-free organocatalysts of C_nC_mImHCO₃ again emphasize that are possible to replace traditional carbenes and offer an environment-friendly methodology for chemical fixation of CO₂.

已发现N-杂环卡宾（NHC）是用于CO ₂化学转化的有效的无卤素有机催化剂，但是，其固有性质对水和空气敏感，这导致了实际应用中的局限性。在这项工作中，我们展示了使用咪唑鎓碳酸氢盐离子液体（C _n C _m ImHCO ₃）的空气和水稳定的有机催化剂，将无卤方法和无金属方法将CO ₂化学固定为环状碳酸酯和甲胺的有价值的化学物质。对于各种底物，在温和的条件下可获得良好或优异的环状碳酸酯和甲胺收率。机制见解表明，C _n C _m作为N-杂环卡宾的有机预催化剂，ImHCO ₃可以与作为转化CO ₂的活性物质的卡宾CO ₂加合物（C _n C _m Im-CO ₂）平衡。结果，C _n C _m ImHCO ₃的无卤和无金属有机催化剂再次强调可以替代传统的卡宾，并为化学固定CO ₂提供环境友好的方法。