VIBRONIC INTENSITIES IN THE ELECTRONIC-SPECTRA OF TRANSITION-METAL COMPLEX-IONS .8. VIBRATIONAL COORDINATES FOR OCTAHEDRAL IONS AND THEIR APPLICATION TO THE A-4(2G) REVERSIBLE E-2(G) TRANSITION OF THE MNF6(2-) ION

A reexamination of the vibrational coordinates appropriate in vibronic intensity calculations in octahedral coordination compounds is presented. We derive a complete set of symmetry coordinates that is orthonormal and transforms correctly under the group generators. The vibronic hamiltonian for the crystal field and ligand polarization contributions to the intensity are calculated in the basis of these coordinates. The crystal field term is evaluated both using a truncated basis set for the intermediate electronic states and using the closure approximation. These methods have been applied to the calculation of the vibronic intensity distribution for the 4A2g <--> 2E(g) transition of the MnF6(2-) ion and close agreement wtih experiment achieved.