For both iridium PCs, [Ir(ppy)2(dtbbpy)]PF6 and [Ir(dF(CF3)ppy)2(dtbbpy)]PF6, the MLCT/LLCT absorption band remains relatively unchanged after irradiation in THF, DMF and MeCN, but at wavelengths below 300 nm, the spectra are typically blue-shifted compared to those before irradiation. This implies that structural changes are likely occurring on the ancillary ligand during the pinacol coupling reaction, a conclusion that is consistent with the work of Bawden et al. who showed that 2,2'-bipyridine type ancillary ligands, when used in combination with hydrogen atom transfer (HAT) electron donors, are susceptible to reaction;