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.