CORRELATION OF VIBRATIONAL AND ELECTRONIC-SPECTRA .2. STATIC AND VIBRONIC CONTRIBUTIONS TO THE POLARIZED SPECTRUM OF TRISETHYLENEDIAMINENICKEL(II) DINITRATE

The transition energies and intensity distributions in both linearly and circularly polarized spectra of [Niens(3)][NO3](2) have been reproduced quantitatively within the cellular ligand-field model. In addition to the Racah B parameter for the interelectron repulsion energies, transition energies required only one ligand-field parameter. Following a normal coordinate analysis of vibrational frequencies, the relative intensities of five observed bands in linear polarization and of three bands in the crystal axial circular dichroism spectrum have been reproduced subsequently with just one variable. The absolute magnitude of the rotatory strength or, equivalently, the intensity of the CD spectrum relative to the linearly polarized spectrum is reproduced within 17% of one experimental estimate; however, two independent experimental measures of this quantity differ by nearly a factor of 4. It is shown that even that difference can be accounted for on recognition of a small contribution from bent bonding in this complex.