On the Coupling Scheme in Uranyl Complexes

Simple theoretical considerations of the ligand field type have been applied to the electronic structure of insular uranyl complexes. The study of the consequences of equatorial ligation is used as a means to test the applicability of different coupling schemes for the isolated uranyl ion. From the analysis of the spectra of a large number of different uranyl complexes of D_nh symmetry, it was previously shown how the effect of equatorial ligation consists in lifting certain degeneracies of the free uranyl electronic energy levels and introducing variations in the corresponding transition probabilities. In this note the equatorial field operator is successively applied to uranyl wavefunctions derived in a Russell‐Saunders approximation, in an $\mathrm{\omega \; ‐\omega }$ coupling approximation, and in an intermediate scheme. Only Russell‐Saunders coupling allows a satisfactory explanation of the observed splitting and intensity pattern.