Actinoid(III) HydrationFirst Principle Gibbs Energies of Hydration Using High Level Correlation Methods

The Gibbs energies of hydration of actinoid(III) ions are evaluated for density functional optimized geometries of [An(H2O) h ]3+ complexes (h = 8, 9) at the coupled cluster singles, doubles, and perturbative triples level by means of the incremental scheme. Scalar-relativistic 5f-in-core pseudopotentials for actinoids and basis sets of polarized triple-ζ quality were applied. The calculated Gibbs energies for the octa- and nona-aquo complexes agree within 1% with the experimental values which are available only for uranium and plutonium. Compared to the hydrate complexes of the lanthanoid(III) ions those of the actinoid(III) series are slightly less stable.