This divergence in yield between the two isomers is likely due to mer-Ir(pmi)3 struggling to oxidize the Cu II , which has an estimated Eox of 0.72 V vs SCE. In the absence of copper catalyst and light, there is virtually no product formation (7 and 8% yield, respectively Table ). However, there is a significant background reaction in the absence of PC, exciting at both 390 nm (53% yield) and 427 nm (44% yield) (Table ), illustrating that direct photoexcitation of the Cu II intermediate directly initiates this reaction.