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

Abstract

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.