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Title: Synthesis conditions and thermal parameters for Cs/sub 4/((NpO/sub 2/)/sub 3/Cl/sub 6/NO/sub 3/H/sub 2/O) (in Russian)

Journal Article · · Sov. Radiochem. (Engl. Transl.); (United States)
OSTI ID:6668271

Simple methods are given for synthesizing Cs/sub 4/(NpO/sub 2/)/sub 3/Cl/sub 6/NO/sub 3/H/sub 2/O) (I), based on the interaction of Cs/sub 3/(NpO/sub 2/Cl/sub 4/) (II), Np(IV) hydroxide, or Cs/sub 2/(NpO/sub 2/Cl/sub 4/) with solutions of CsNO/sub 3/ in aqueous alcohol containing hydrochloric acid. The formation conditions for compounds I and II are analogous, and their deposition is dependent on the relation between NO/sub 3//sup -/ and Cl/sup -/ in the solution. The synthesis of compound I is considered from the viewpoint of replacement of Cl/sup -/ by NO/sub 3//sup -/ and H/sub 2/O in the coordination sphere on going from (NpO/sub 2/Cl/sub 4/)/sup 3 -/ to the mixed aquaacid complex ((Np(1)O/sub 2/)/sub 2/Cl/sub 4/Np(2)O/sub 2/Cl/sub 2/NO/sub 3/H/sub 2/O)/sub n//sup 4n-/. Features of the substitution are noted that are related to changes in the coordination numbers of the neptunium atoms, and to polymerization and unequal distribution of the Cl/sup -/, NO/sub 3//sup -/, and H/sub 2/O between the neptunoyl ions in compound I. Compound I begins to decompose above 300/sup 0/C in air with the formation of NpO/sub 2/ and a new crystalline compound, which contains neptunium in the degrees of oxidation (V) and (VI). The supposed composition for the new compounds is indicated by the pyrolysis and by the spectroscopic data as Cs/sub 3/O/sub 0 x 5/(Np/sup (V)/O/sub 2/)(Np/sup (VI)/O/sub 2/)Cl/sub 6/ (III). Compound III dissociates in the range 400-535/sup 6/C with the formation of compound II, CsCl, and NpO/sub 2/. In the range 700-1180/sup 0/C, the cesium distills off as CsCl, and the final product is NpO/sub 2/. It is assumed that the first stage of decomposition for compounds I is accompanied by disproportionation of the neptunium as a result of electron transfer between the two Np(V) atoms linked by the bridge oxygen atoms in the Np(2)O/sub 2//sup +/ cations. The proposed structural formula for the anion complex in compound III is the octamer ((Np/sup (V)/(1)O/sub 2/)/sub 2/(Np/sup (V)/(2)O/sub 2/)/sub 2/(Np/sup (VI)/O/sub 2/)/sub 4/Cl/sub 24/)/sup 12 -/.

OSTI ID:
6668271
Journal Information:
Sov. Radiochem. (Engl. Transl.); (United States), Vol. 28:3; Other Information: Translated from Radiokhimiya; 28: No. 3, 311-318(May-June, 1986)
Country of Publication:
United States
Language:
Russian

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