Since iodide is easier to oxidize than bromide, we next explored increasing the overpotential for Ir(IV) reduction with tetrabutylammonium iodide (TBAI) additive to further increase the rate of catalyst recovery. However, the reaction with TBAI (entry 5) performed worse than no additive. This loss in performance could be due to the formation of I2 •-and I3 -when iodide is used as an additive. Oxidation of iodide by Ir(IV) is expected to be faster than bromide and the production of X2 •- and X3 -intermediates is also faster with iodide. The reactivity of these intermediates or the ability of I3 -and I2 •-to absorb blue light could potentially explain the differences in reactivity between iodide and bromide additives.