The UV-vis absorption spectra of the four complexes were recorded in acetonitrile solution (Figure and Table ). The absorption spectra of the four complexes show similar profiles, with strong absorption bands at high energy (λabs < 230 nm, ε > 60 000 M -1 cm -1 ) attributed to ligand-centred (LC) π-π* transitions. The low energy shoulder around 300 nm (ε ≈ 15 000 M -1 cm -1 ) is assigned to a mixed LC/MLCT transition, consistent with the DFT calculations. The absorption spectra are similar to those observed for mer-Ir(tfpmi)3. All four iridium complexes show deep blue emission in acetonitrile solution. The emission is structured, with emission maxima, lPL, observed at 425-427 nm for the mer isomers in addition to a high energy shoulder at 415 nm. The emission spectra of the fac complexes are blue-shifted by ca 5 nm (35 meV), with lPL of 420-421 nm, consistent with the moderate increase in the calculated triplet energies. The mer isomers have the same lPL and structured emission spectra as that observed for mer-Ir(tfpmi)3, indicating that the pendant bulky groups have little impact on the emission energy or character of the emissive T1 state of the complexes.