The influence of relativistic effects and the crystal field on the properties of actinyl ions

The electronic structure and properties of the most covalent compounds of the actinides, namely the actinyl ions AnO₂²⁺ (An = U, Np, Pu, Am, Cm, Bk, and Cf), have been analysed on the basis of X_α-SW calculations. The regularity of the change in the redox, crystal-chemical, spectral, magnetic, and other properties in a series of compounds containing the actinyl ions has been studied. The strictly regular, regular, or irregular (stepwise) nature of the dependence of different properties on the atomic number of the element is determined by the extent of the participation of the 5f- and 6d-electrons in chemical bond formation, that is by the crystal field effect and the influence of relativistic spin–orbit coupling. The bibliography includes 174 references.