The fully charged catalyst, Rh I phenPer was selectively generated via the three following pathways: i) chemical reduction by a formate-driven thermal reaction 35 (see Fig. ), ii) electrochemical reduction (see violet line in Fig. ), and iii) photochemical reduction upon LED-illumination in the presence of triethylamine (TEA) as sacrificial electron donor (see Fig. ). In the latter reaction, the initial photoexcitation at 400 nm (14 mW cm -2 ) of Rh III phenPer occurs on the Per chromophore leading to charge transfer to the Rh center (cf. photoinduced dynamics results). Based on the TA studies of Rh III phenPer, it seems plausible that the Per •+ moiety of [(phenPer •+ )Rh II (Cp*)Cl] + is reduced by TEA. A second photoexcitation and electron transfer event forms the two-fold reduced, catalytically active Rh I center. Alternatively, the Rh I species can be formed by disproportionation of two Rh II complexes. For the reductive quenching by TEA a diffusion-controlled minimum time of 9 ns can be estimated (see SI section 4.2). Therefore, the quenching efficiency of the charge-separated state (lifetime of 280 ps) with TEA can be estimated to 3%. This is why, the light-driven Rh III/I reduction of Rh III phenPer is slow compared to the structurally related complex Ru II -tpphz-Rh III . 5.1 Chemical formation