We also assessed the efficiency of the isomers of Ir(pmi)3 as photoredox catalysts in the atom radical transfer addition (ATRA) of sulfonyl chlorides and allyl trifluoroborate salts. This reaction proceeds via the putative oxidative quenching of PC* by p-toluenesulfonyl chloride (Ered = -0.94 V vs. SCE). The reduced sulfonyl chloride liberates a chloride ion, forming a radical cationic intermediate. Subsequently, the PC +• oxidizes the allyl trifluoroborate (Eox = 1.1 V vs SCE), liberating BF3 and an allyl radical, which undergoes radical-radical cross-coupling with the sulfonyl radical affording the allyl sulfone product. We chose this reaction as the radical cation of the PC must be sufficiently oxidizing to enable the formation of the allyl radical while the PC* must be sufficiently photoreducing to generate the sulfonyl radical, necessitating a balanced set of ground-and excited-state redox potentials, unlike transformations such as the dehalogenation reaction where sacrificial oxidants/reductants can be interchanged to align with the redox potentials of the PC. In the literature, the use of fac-Ir(ppy)3 in this reaction produced a modest yield of 50%. When this reaction was run using our photoreactors and this PC, a comparable yield of 44% was achieved. When the PC was changed to fac-and mer-Ir(pmi)3 the yields surprisingly diverged depending on the configuration at iridium at 60 and 40%, respectively (Figure ). This is correlated to the slightly lower Eox of the mer-isomer (Eox = 0.64 V vs. SCE) compared to fac-Ir(pmi)3 (Eox = 0.71 V vs. SCE). To the best of our knowledge, this is the first example where the impact of the configuration at the metal centre on the reaction yield has been probed in photocatalysis.