The Nephelauxetic Effect in Praseodymium(III) and Neodymium(III) Complexes

The absorption spectra of praseodymium(III) and neodymium(III) complexes were measured in an aqueous alkaline solution with an excess of ligands. The experimental data being used, the Racah parameter, E3, and the Landè parameter, ζ4f, were calculated by the least-squares method on the assumption that the energy separation between J-levels of the 4fn-configuration is a function of E3 and ζ4f. The nephelauxetic effect in the Pr(III) and the Nd(III) complexes was then discussed by using the values of E3 thus obtained.