Influence of Ligand Substitution on Uranium–Ligand Bond Energies in the Equatorial Plane of Uranyl Compounds*

In this paper, a general treatment of the chemical mutual influence of ligands in the equatorial plane of the uranyl ion UO22+ is described. The description based on the use of empirical theoretical methods. In the frame of these methods, the uranium–ligand bond energies in the coordination sphere of the uranyl compounds UO2(NO3)2L2 and UO2(C2O4)2L2 (L is mono- or bidentate ligand) are calculated. Two kinds of regularities are considered and classified: the proportional dependence between the bond energy of L and bond energy of other ligands (“Fid-effect” of the first type) and the reversibly proportional dependence between these bond energies (“Fid-effect” of the second type). The chemical nature of both effects is described. The ligands are classified in the frame of potential application for liquid–liquid extraction.