Optical transitions of a D4h complex with one electron in a1g (≈3z2−r2): study of RhCl64−

Optical transitions of the elongated RhCl64− complex in NaCl have been calculated in the DFT framework together with the oscillator strength of allowed γ → a1g charge transfer (CT) transitions. The experimental peak at 3.66 eV is shown to arise from a jump from a2u(ax) mainly built from axial ligands and thus the onset of CT transitions for RhCl64− appears at a lower energy than that for RhCl63−. This fact is partially related to the Jahn–Teller effect in RhCl64−. The present calculations on RhCl64− also explain the crystal field spectrum and predict the existence of additional CT transitions in the 4–5 eV range.