Chapter 8: IR Spectro-electrochemistry and Group-6 α-diimine Catalysts of CO₂ Reduction

The complex [Re(CO)₃(bpy)Cl] (bpy=2,2′-bipyridine) has been known for several decades as the catalyst precursor for both electrochemical and photochemical reduction of CO₂, currently being outperformed by the cheaper and Earth-abundant manganese congeners. On the other hand, the catalytic potential of the related group-6 tetracarbonyl α-diimine complexes has only recently been discovered, showing particularly strong dependence on the cathodic material initially revealed by cyclic voltammetry and IR spectro-electrochemistry. This chapter tackles in some detail these general aspects, including fundamental experimental techniques used to investigate the cathodic behaviour and the electronic structures of group-6 [M(CO)₄(α-diimine)] and related Re complexes as well as their reduced forms.