Photo‐ and Electrochemical Properties of a CO₂ Reducing Ruthenium–Rhenium Quaterpyridine‐Based Catalyst

The bridging ligand 2,2′,5′,3′′,6′′,2′′′‐quaterpyridine was utilised to tether [(bpy)₂Ru]²⁺ and [Re(CO)₃Cl] subunits for the purpose of photocatalytic CO₂ reduction. The photophysics and electrochemistry of the complex and associated mononuclear species are reported herein, in addition to photocatalytic, picosecond time‐resolved infrared and computational studies. Photophysical, time‐resolved IR, and electrochemical data together with quantum chemical calculations indicate weak communication between the two metal centres. As a result of the electron‐withdrawing effect of the ligand on both the Ru and Re subunits, the reducing power of the photosensitiser and catalytic unit were significantly attenuated relative to the intermolecular approach utilising [(bpy)₃Ru]²⁺ and (bpy)Re(CO)₃Cl.