LAUSR

Environmental problem caused by carbon emission is of widespread concern. Involving CO 2 as C1 resource into chemical synthesis is one of the most attractive way for carbon recycling. Herein, we present the first example of host-guest composites featuring MOF-encapsulated binuclear N-heterocyclic carbene (NHC) complex, Co 2 @MIL101, with the molecularly dispersed [Co(IPr)Br] 2 (μ-Br) 2 ( Co 2 ) loading in the cage of MIL-101(Cr) via a "ligand-in-dimer-trap" strategy, which is comprehensively investigated through various techniques including synchrotron X-ray absorption, electron microscopes, X-ray diffractions, solid-state NMR, etc. The noble-metal-free double sites catalyst Co 2 @MIL101 exhibits promising stability, activity, efficiency, reusability and substrate adaptability for converting CO 2 into various formamides with amines and hydrosilanes, and achieves the best performance for one of the most useful formamides, N-methyl-N-phenylformamide (MFA) among the recyclable catalysts at ambient conditions, providing a reliable approach to successfully unify the advantages of both homo- and heterogeneous catalysts. DFT calculations are applied to illustrate the superior activity of the binuclear NHC complex center as double sites catalyst toward the activation of CO 2 .