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 ac entric chromophores was presented in part 1. Here, that model is exten ded 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 sc heme, although time-averaged t variables for each vibrational mode sub sume local electronic properties and ligand displacements within each vibrational normal mode. The (L)t(lambda) parameters of the 'static' m odel are replaced in the dynamic regime by (L)t(lambda)alpha where alp ha = x or y for local bending displacements normal to the metal-ligand (z) vector and alpha = z for pure stretching displacements. The physi cal and bonding significance of static- and dynamic-type parameters ar e described and compared.