Irradiation of an Ar-saturated solution of 4a 2+ with a green LED in the presence of a high benzene concentration leads to rapid catalyst decomposition, most likely via 4a •+ , given that the catalyst is completely stable in the absence of the quencher benzene (Figure /B). However, 4a 2+ is almost photostable when the solution is additionally saturated with oxygen, suggesting that an electron transfer with 4a •+ regenerates 4a 2+ . Related catalyst regeneration steps starting from acridinium radicals were observed previously. LiClO4 slightly improves the stability of 4a 2+ under our conditions, but O2 clearly has a more pronounced effect. Similar observations were made during NMR-scale irradiation experiments (see above). In addition to the catalyst regeneration step, O2 is assumed to facilitate the formal hydrogen atom elimination being required for the formation of the stable C-N coupling product (Figure ). This reasoning is in agreement with the abovementioned NMR-scale experiments, which only gave traces of the desired azolation product 7. Taking into account all experiments presented herein and the findings from prior studies on this reaction class with highly oxidizing catalytic systems, the mechanism can be summarized as displayed in Figure . Interestingly, neither multi-photon nor electrochemical strategies are required for the formation of the arene radical cation. This straightforward and versatile monophotonic C-N coupling approach was enabled through the development of novel hybrid catalysts.