B3LYP, RHF and PM5 theoretical studies on phosphorescent cyclometalated Ir(III) complexes

PM5, RHF/3-21G and B3LYP/cc-pVDZ ground sate geometries are reported for two Ir(III) complexes with cyclometalated and β-diketonate ligands. Subsequently, electronic spectra were predicted using time-dependent density functional (TD-DFT) at PM5 and B3LYP/cc-pVDZ geometries. Despite the fact that PM5 predicts reasonable interatomic distances in the coordination polyhedron, this method presents large deviations in the N1–C2–C3–C4 dihedral angle, in cyclometalated ligands, when compared to X-ray geometries. B3LYP and RHF methods thus seem to be more suitable to predict ground state geometries for both complexes, whereas TD-DFT calculations, using B3LYP/cc-pVDZ geometries, yield excited states in good agreement to experimental ones.