Low Potential CO₂ Reduction by Inert Fe(II)‐Macrobicyclic Complex: A New Concept of Cavity Assisted CO₂ Activation

Abstract The advantage of a pre‐organized π‐cavity of Fe(II) complex of a newly developed macrobicycle cryptand is explored for CO₂ reduction by overcoming the problem of high overpotential associated with the inert nature of the cryptate. Thus, a bipyridine‐centered tritopic macrobicycle having a molecular π‐cavity capable of forming Fe(II) complex as well as potential for CO₂ encapsulation is synthesized. The inert Fe(II)‐cryptate shows much lower potential in cyclic voltammetry than the Fe(II)‐tris‐dimethylbipyridine (Fe‐MBP) core. Interestingly, this cryptate shows electrochemical CO₂ reduction at a considerably lower potential than the Fe‐MBP inert core. Therefore, this study represents that a well‐structured π‐cavity may generate a new series of molecular catalysts for the CO₂ reduction reaction (CO₂RR), even with the inert metal complexes.