MODELING THE SUBSTITUTION EFFECTS OF SEVERAL RHODIUM(III) TRANSITION-METAL COMPLEXES USING THE ANGULAR OVERLAP MODEL

The influence of the ligand and the effect of substitution of a single ligand on the electronic spectra of several rhodium(III) transition m etal complexes are studied. We interpret optical absorption data (d-d transitions) for known rhodium(III) complexes by means of a ligand-fie ld treatment and we predict the electronic spectra (ligand-field trans itions) of rhodium(III) complexes unknown until yet, i.e. complexes on which no optical data have been reported until now. Realistic values for sigma- and pi-parameters are presented in good agreement with lite rature data. The 'ligand-independent' (1)A(2) <-- (1)A(1) transition f or mono-substituted (C-4v) rhodium(III) compounds (used as electron tr apping dopants in photographic films), can be used as a reference ener gy 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 pho tographic behaviour for mono-substituted compounds in comparison with the hexa-complexes, can be understood and explained by the influence o f this ligand substitution on the splitting and shifting of the excite d states. (C) 1998 Elsevier Science B.V. All rights reserved.