Hydrogen Peroxide in the Chemistry of f-Elements.

The properties of H2O2 and its reactions with lanthanide and actinide ions are considered. The potential values of pairs involving H2O2 in acidic and alkaline solutions are given. Depending on the oxidative potential of the f-element ion and pH, H2O2 exhibits oxidizing or reducing properties. The kinetics and mechanisms of reactions of H2O2 with lanthanides(II–IV) and with actinides(III–VII) in acidic, carbonate, and alkaline media have been analyzed. Ions of f-elements(III–VI) form peroxide complexes. The peroxo group occupies either one (OOH) or two (OO) coordination sites. U(VI), Np(IV) binds up to 3 peroxo groups. Oxidation or reduction reactions proceed intramolecularly. In the case of Yb2+, Sm2+, U3+, Ce4+ (in an acid solution), Pr(IV) and Am(IV) (in a weakly acidic medium), the bimolecular rate constants are 105–n × 106 L/(mol s), which exceeds the rate of ligand exchange in the coordination sphere of the f-element ion. Therefore, charge transfer occurs in the outer sphere. Coordination spheres of Ce(IV) oxalate, Tb(IV) with P2W17O6110–, and Np(VI) with NO3– slow down the charge transfer between H2O2 and the f-element ion. H2O2 arising during the radiolysis of aqueous solutions is in an excited state and is more active than H2O2 introduced from the outside. Of particular interest are the reactions of H2O2 with ions of f-elements in strongly complexing or nonaqueous (organic) media, as well as structural studies of solid compounds of peroxides of f-elements. [ABSTRACT FROM AUTHOR]