C. J. Ballhausen

Ligand‐Field Treatment of the Jahn—Teller Distortion in VCl4

A ligand‐field treatment of the Jahn—Teller distortion in VCl4 is developed using perturbation methods. Several of the results are at variance with those obtained earlier by means of the electrostatic crystal field model, and are in substantial agreement with some recent molecular orbital calculations. It is found that distortions are of the same order of magnitude as the relevant zero‐point vibrational energies so that no ``static effect can be expected. This is in accordance with the available experimental evidence. Our results suggest certain splittings in the infrared and Raman spectrum of VCl4. On the basis of the present experimental evidence the consequences of such a ``dynamic Jahn—Teller effect can neither be confirmed nor contradicted with certainty.

On the Optical Spectra of Some Transition Metal Pentacyanonitrosyl Complexes

The visible absorption spectra of the ions [Fe(CN)5NO]2—, [Mn(CN)5NO]3—, and [Cr(CN)5NO]3— are interpreted using a crystal field level scheme of C4v symmetry. Assuming a strong axial compression to be present a self‐consistent assignment is obtained for both the 3d5 and 3d6 electronic configurations.

Crystal Spectra of Hexaurea Complexes. III. Optical and Magnetic Properties of Crystals Containing the Hexaurea Vanadium (III) Ion

Low‐temperature polarized crystal spectra of the [V(urea)6]3+ ion are presented and discussed. In many ways they closely resemble those seen in V3+/Al2O3. The ground‐state splitting of 3A2 has been established by both optical and magnetic means and is reported as 6.0u2009±u20090.5 cm−1. The source of spectral intensity is almost entirely due to the influence of the static, odd crystal field.