Scheme defining rate constant. (C) Kinetic spectroelectrochemistry experiment. Ir(ppy)3 was oxidized to completion and the UV-vis signal at λprobe = 600 nm was monitored over time. At t = 2 min, the potentiostat was turned off. At approx. t = 6 min, degassed solutions were injected. certainly possible, for example the radical addition of Br• to a Ni(II) or Ni(III) intermediate, the OMebpy ligand, the substrate, or the nucleophile. We did not detect bromination of the aryl halide substrate or product via F NMR (See SI, Fig. ) and the reaction proceeds to high yield, suggesting a low frequency of termination pathways that lead to Ni catalyst destruction or modification of the coupling partners.