Neptunium chlorides

X-ray powder diffraction data reveal that CP3UCI and Cp3ThCl are isomor-phous. Tris(cyclopentadienyl)thorium derivatives of other halides, alkoxides, tetrahydroborates, etc., can be prepared in a manner analogous to the uranium reaction above [58]. Tris(cyclopentadienyl)neptunium chloride, Cp3NpCl, can be prepared either by a radiochemical synthesis [75] ... 

The Heat of Solution of Neptunium Metal and the Heats of Formation of Some Neptunium Chlorides. A Microcalorimeter for Heat of Solution Measurements, E.F. Westram Jr. and L. Eyring, J. Amer. Chem. Soc., 74,2045-2047 (1952). 

In general, the absorption bands of the actinide ions are some ten times more intense than those of the lanthanide ions. Fluorescence, for example, is observed in the trichlorides of uranium, neptunium, americium, and curium, diluted with lanthanum chloride (15). 

A radiochemist isolates 8.6 /ng of a chloride of neptunium (atomic weight = 237 g/mole), which she proves has the formula NpCl3. in trying to find the possible valence states of Np, she finds that titration of the 8.6 /xg sample requires 37.5. 1 of 0.00200 N KMn04 solution. To what electrical charge must the Np have been oxidized ... 

For the larger chloride ion, the final member in the series is the tetrachloride, An02CLi A The uranium, neptunium, and plutonium tetrachloride dianions have been isolated with a number of different cations, for example, Na+, NH4+, K+, Cs+, K+18-crown-6, and so on. The An=0 distances were found to be 1.768, 1.751, and 1.737A for An = U, Np, and Pu, respectively. The An-Cl distances in these complexes is virtually unchanged 2.675 A (U), 2.659 A (Np), and 2.656 A (Pu). These stmctural data suggest that the chloride hgands are bound in essentially a purely ionic manner while the covalent nature of the An=0 bond is preserved. 

Ishimori u. Mitarb. verwendeten Dodecylbenzolsulfonsanre (DBSA) in Diathylather als Solvens und verteilten 60 Elemente als Chloride 256,257). Mit dem gleichen Solvens, gelost in einem Gemisch aus Diathylather und Athylacetat, lassen sich Neptunium in vier-, fiinf- und sechs-wertigem Zustand, Thorium (IV), Protaktinium (V) und Uran (VI) aus Mineralsauren extrahieren 400). 

The actinides are base metals which require the reduction of a chloride or fluoride with sodium or barium for their isolation. Neptunium, for example, has been made by reducing its trifluoride with barium vapour at 1200°. The need for such drastic methods is understandable because the heats of formation of the ions are as much as three times greater than that of the Pt ion. The metals are silvery white and, except thorium and americium, have high densities. 

The thorium is removed from the column with 12N HCl, since it does not form a chloride complex, to separate it from neptunium and plutonium. The plutonium is removed by reduction to Pu(III) with 12N HCl-O.lM NH4I solution. The neptunium is then removed by dilute acid. The neptunium and plutonium can also be eluted together with dilute acid and the various nuclides determined by alpha spectrometry. 

For the mutual separation of plutonium and neptunium, both of those are adsorbed on an anion-exchange resin column and the resin converted to chloride form by washing with concentrated hydrochloric acid. Then the plutonium is reduced to the trivalent state and eluted with 9 H hydrochloric acid solution containing 0.1 M hydro-iodic acid. 

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]

Duyckaerts, Landresse and Lysy reported investigations of the solubility of various uranium and neptunium oxides in the molten KCl-LiCl eutectic at 660 °C [231, 252], The solubility product of Np02 in the chloride melt was estimated to be pPNp02 = 20.3 0.5 [252]. 

Neck, V., Fanghanel, T., Rudolph, G., Kim, J. I., Thermodynamics of neptunium(V) in concentrated salt solutions Chloride complexation and ion interaction (Pitzer) parameters for the Np02 ion, Radiochim. Acta, 69, (1995), 39-47. Cited on page 104. 

Neptunium diarsenide, formed by heating the hydride and arsenic in a sealed tube at ca. 320 for a week, has a powder pattern that indicates a FegAs structure. Heating the compound to 640 °C yields the monoarsenide, with a sodium chloride structure. Both plutonium and americium monoarsenides can be obtained from reactions of the hydride and arsenic at ca. 320 C. 

The reaction rate is also sensitive to chloride ion concentration. The overall reaction between neptunium(iii) and uranium(vi)... 

The advantage of this method over the others described in the preceding sections is that the lithium chloride is soluble in methanol, making the separation of insoluble methoxides easily possible. The method was later extended by other workers for the preparation of methoxides of beryllium, " lanthanum,uranium, neptunium, vanadium, iron, ° and copper. ... 

AnBr3 compounds can be prepared by reaction of HBr with the proper actinide hydride, hydroxide, oxalate hex-ahydrate, or oxide. Structures similar to the trichlorides are observed with the structural change from nine coordination to eight coordination occurring with 6-neptunium tribromide. The triiodides to a-americium triiodide have the same eight-coordinate structure found for the heavier bromides and chlorides. From 6-americium triiodide on, the metals are six coordinate. Thl3 is best formulated as Th(IV), 31, and le. ... 

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