Lewis acid-promoted self-sensitized photocatalytic CO2 reduction by a bimetallic Fe complex.

The modified macrocyclic Mabiq ligand, MeOMbq, contains two methoxy groups at the outer biquinazoline unit that allow for coordination of a second metal ion in the absence of auxiliary ligands. A series of bimetallic MFeMeOMbq complexes was synthesized, containing Na, Mg, Fe or Zn adjacent to a centrally bound ferrous ion. The redox properties correlate with the Lewis acidity of the supporting metal. Both Fe and Zn in the outer site boost the photocatalytic CO2 reduction activity of the central ferrous site. The bimetallic ZnFeMeOMbq achieves up to 140 TONs (1 h) for selective CO2 to CO conversion in a self-sensitized process.