Modelling the substitution effects of several rhodium(III) transition metal complexes using the angular overlap model Original Research Article

The influence of the ligand and the effect of substitution of a single ligand on the electronic spectra of several rhodium(III) transition metal complexes are studied. We interpret optical absorption data (d–d transitions) for known rhodium(III) complexes by means of a ligand-field treatment and we predict the electronic spectra (ligand-field transitions) of rhodium(III) complexes unknown until yet, i.e. complexes on which no optical data have been reported until now. Realistic values for σ- and π-parameters are presented in good agreement with literature data. The `ligand-independentʹ 1A2←1A1 transition for mono-substituted (C4v) rhodium(III) compounds (used as electron trapping dopants in photographic films), can be used as a reference energy level when positioning the electronic states of these compounds vs. the valence and the conduction band of the AgCl photographic system. As shown in this work for some rhodium(III) complexes, a change in photographic behaviour for mono-substituted compounds in comparison with the hexa-complexes, can be understood and explained by the influence of this ligand substitution on the splitting and shifting of the excited states.