In this work, we have constructed a Ir single-atom substituted polyoxometalate (POM) salt K[PWOIr] (K-PWIr). The characterization by XRD, FT-IR, HAADF-STEM and XAFS confirmed that the single-atom Ir was anchored into the framework of the POM. The binary catalytic system K-PWIr and ionic liquid bis(1-butyl-3-methylimidazolium) malonate ([BMIM][Mal]) demonstrated outstanding catalytic activity for N-formylation of amines with CO/H, and TON values can reach as high as 448000. The [BMIM][Mal] played a crucial role in adsorption of CO and the isotopically labeled experiments confirmed that the ionic liquid aced as a shuttle to transport carbon dioxide from gas phase to catalytic Ir sites. Besides, the [BMIM][Mal] showed electron interaction with Ir sites, which can stabilize the catalytically active Ir sites. Detailed investigations confirmed the H underwent heterolytic dissociation on Ir-O sites and the reaction was proceeded via a formate intermediates.

中文翻译：

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离子液体在多金属氧酸盐稳定铱单原子催化剂上促进胺的 N-甲酰化

在这项工作中，我们构建了一种 Ir 单原子取代的多金属氧酸盐 (POM) 盐 K[PWOIr] (K-PWIr)。 XRD、FT-IR、HAADF-STEM 和 XAFS 表征证实单原子 Ir 锚定在 POM 的框架中。二元催化体系K-PWIr和离子液体双(1-丁基-3-甲基咪唑鎓)丙二酸酯([BMIM][Mal])对胺类与CO/H的N-甲酰化反应表现出优异的催化活性，TON值可达高达448000。[BMIM][Mal]在CO吸附中发挥着至关重要的作用，同位素标记实验证实离子液体作为穿梭机将二氧化碳从气相运输到催化Ir位点。此外，[BMIM][Mal]表现出与Ir位点的电子相互作用，这可以稳定催化活性Ir位点。详细研究证实 H 在 Ir-O 位点上发生异解解离，并且反应是通过甲酸酯中间体进行的。