A CELLULAR LIGAND-FIELD MODEL FOR L-L SPECTRAL INTENSITIES .4. PARAMETRIC STRUCTURE FOR DYNAMIC SOURCES

The model for d-d or f-f intensities of ligand-field transitions in acentric chromophores was presented in part 1. Here, that model is extended to include centrosymmetric systems in which intensity is deemed to arise from parity mixing induced during ungerade molecular vibrations. The same cellular structure is maintained for the parametrization scheme, although time-averaged t variables for each vibrational mode subsume local electronic properties and ligand displacements within each vibrational normal mode. The (L)t(lambda) parameters of the 'static' model are replaced in the dynamic regime by (L)t(lambda)alpha where alpha = x or y for local bending displacements normal to the metal-ligand (z) vector and alpha = z for pure stretching displacements. The physical and bonding significance of static- and dynamic-type parameters are described and compared.