Neptunium fluoride complexes

Table IV. Some Alkali Fluoride Protactinium ( V ), Uranium ( V ), Neptunium(V), Plutonium(V) Fluoride Complexes"...

Solid Compounds. The literature (2, 5, 8, 9, 12) on solid actinide fluoride complexes is extensive, and many new compounds are being prepared. For example, Thoma, Friedman, and Penneman (12) reported the first preparation of complex fluorides formed between UF3 and the alkali fluorides KF, RbF, and CsF. This section summarizes the work which was performed concerning the solid compounds resulting from neptunium in saturated KF solution. 

Binary halides. A number of homoleptic halides of pentavalent protactinium, uranium, and neptunium have been reported. In particular, the fluoride complexes AnFs are prepared by high... 

Absorption spectra have been obtained for certain actinide ions which are soluble in saturated KF solution U(IV), Np(IV), Np(V), Np(Vl), and Am(III). Oxidation-reduction reactions of neptunium have been studied. Four new complex fluorides have been prepared and identified by x-ray powder patterns a-K NpFe, pi-K NpFs, KNPO2F2, and K3NPO2F3. Three additional complex fluorides, of Np(III), Np(V), and U(VI), have been prepared but not identified. 

Dissolution of the calcium fluoride in aluminum nitrate-nitric acid oxidizes the plutonium to the tetravalent hexanitrate complex (3), while the transplutonium nuclides remain in the trivalent state. The only actinides retained by a nitrate-form anion-exchange column are thorium, neptunium, and plutonium. The uranium distribution coeflBcient under these conditions is about ten, but uranium should not be present at this point since hexavalent uranium does not carry on calcium fluoride (4). 

The donor action of [NOs]" as an anionic ligand towards thorium(iv) and uranium(iv) in the presence of trimethylphosphine and tris(dimethylamino)phosphine oxide in aqueous media has been found to be very similar. The larger nitrate ion was observed to form more stable species with thorium than the chloride ion whereas in the uranium(iv) case both complexes formed equally readily. A study of the sulphate complexes of uranium(iv), neptunium(vi) and plutonium(vi) in HCIO4-H2SO4 solution showed the stability constants to follow the order U[Pg.453]

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