Effective Reduction of CO2 with Aromatic Amines into N-Formamides Triggered by Noble-Free Metal-Organic Framework Catalysts Under Mild Conditions

Abstract

The reductive transformation of carbon dioxide (CO₂ ) into high-valued N-formamides matches well with the atom economy and the sustainable development intention. Nevertheless, developing a noble-free metal catalyst under mild reaction conditions is desirable and challenging. Herein, a caged metal-organic framework (MOFs) [H₂ N(CH₃ )₂ ]₂ {[Ni₃ (µ₃ -O)(XN)(BDC)₃ ]·6DMF}_n (1) (XN = 6″-(pyridin-4-yl)-4,2″:4″,4″'-terpyridine), H₂ BDC = terephthalic acid) is harvested, presenting high thermal and chemical stabilities. Catalytic investigation reveals that 1 as a renewable noble-free MOFs catalyst can catalyze the CO₂ reduction conversion with aromatic amines tolerated by broad functional groups at least ten times, resulting in various formamides in excellent yields and selectivity under the mildest reaction system (room temperature and 1 bar CO₂ ). Density functional theory (DFT) theoretical studies disclose the applicable reaction path, in which the CO₂ hydrosilylation process is initiated by the [Ni₃ ] cluster interaction with CO₂ via η² -C, O coordination mode. This work may open up an avenue to seek high-efficiency noble-free catalysts in CO₂ chemical reduction into high value-added chemicals.

Keywords: CO2; N-formamides; cyclicity; metal-organic framework; noble-free metal catalyst.