In summary, an interesting aspect of the emission of this family of complexes is that those with a napththyl-containing carbene ligand (Cu Mes MIC Naph Cz, Cu 3,5-MePh MIC Naph Cz, and Cu Mes MIC Naph NPh2) display phosphorescence emission with vibronic structure, while those bearing a substituted aryl substituent (Cu Mes MIC p-An Cz, Cu Mes MIC 3,5-CF3Ph Cz, and Cu Mes MIC 3,5-CF3Ph NPh2) display emission bands that appear to be more CT in origin. To gain greater insight into the origin of this divergent behaviour, we calculated the electron-hole distribution for the S1 and T1 excited states of the compounds. Although the S1 excited states of Cu Mes MIC Naph Cz, Cu 3,5-MePh MIC Naph Cz, and Cu Mes MIC Naph NPh2 appear to have MLCT character when carbazolide is used as a ligand or have LLCT character when diphenylamide is used as the ligand in Cu Mes MIC Naph NPh2, the T1 state in all three complexes displayed an electronhole distribution that is entirely localized on the napththyl fragment of the carbene ligand (Figure ). This is consistent with the fact that the T1 to S0 simulated emission spectra more closely replicate the experimental data above, suggesting that these complexes are phosphorescent from a naphthyl-centered LE state. In contrast, in the absence of the naphthyl group in the MIC, the electron-hole distribution in the T1 state of Cu Mes MIC p-An Cz, Cu Mes MIC 3,5-CF3Ph Cz, and Cu Mes MIC NPh2 was mainly localized on the carbazolide ligand, with some very small contributions from the Cu atom, indicating a mixed MLCT/LLCT process. The CT origins of the emission in Cu Mes MIC p-An Cz, Cu Mes MIC 3,5-CF3Ph Cz, and Cu Mes MIC NPh2 are consistent with the absence of the vibronic progression that is usually diagnostic of LE states.