Neptunium IV

Comparison of these results for plutonium with those for other tetravalent metals reveals some interesting facts. Thor-ium(IV), uranium(IV) and neptunium(IV) sulfates have been investigated under hydrothermal hydrolytic conditions. For uranium, the stable phases which have been reported include U(0H)2S0i (2), U60i, (OH)i, (SO.,) 6 (2). U (SOi,) 2 4H20 (23) and IKSO (24). 

Burkhart and Newton [J. Phys. Chem., 73 (1741), 1969] have studied the kinetics of the reaction between vanadium (II) and neptunium (IV) in aqueous perchlorate solutions... 

Table 17 Some Hydrates of Thorium(IV), Protactinium(IV), Uranium(IV), Neptunium(IV)...

Because of the ease of oxidation of protactinium(IV) and uranium(IV), peroxides and peroxo complexes are limited to their higher oxidation states. The compounds M04"JcH20 precipitated from dilute acid solutions of neptunium(IV) and plutonium(IV) by hydrogen peroxide appear to be actinide(IV) compounds. Soluble intermediates of the type [Pu( U-02)2Pu]4+ are formed at low hydrogen peroxide concentrations. 

The coordination geometry in anhydrous Th(CF3COCHCOMe)4 is a 1111 ( )4-422) antiprism 74 the structure of the monohydrate has been discussed earlier (p. 1144). Th[CF3COCHCO(2-C4H3S)]4 is isostructural with the cerium(IV), uranium(IV) and plutonium(IV) analogues. The coordination polyhedron is a distorted dodecahedron in which the four ligands span the two perpendicular trapezoids of the dodecahedron.75 In the complexes M(n-C3F7COCHCOBut)4, the thorium(IV), uranium(IV) and neptunium(IV) compounds are isomorphous, but the plutonium compound is not. 

In the structures of compounds of the type M3UF7 the seven F atoms are statistically distributed over fluorite lattice sites.153 The nine-coordinate thorium atom in (NH ThFg is surrounded by a distorted tricapped trigonal prismatic array of fluorine atoms, with the prisms sharing edges to form chains, whereas the uranium(IV) compound contains discrete dodeca-hedrally coordinated [UF8]4 ions. The protactinium(IV), neptunium(IV) and plutonium(IV) analogues are isostructural with the uranium compound.154... 

The formation of complex compounds of neptunium with cupferron and a number of other complexing agents has been studied.95 More recently, the extraction of neptunium(IV and VI) from HC1, HBr and HN03 media has been investigated.96... 

Laurinat, J.E. 2006. SASSE modeling of first cycle neptunium(IV) recovery flowsheet. WSRC-TR-2006-00187, Rev.0. 

Taylor, R.J. Sinkov, S.I. Choppin, G.R. May, I. Solvent extraction behavior of neptunium (IV) ions between nitric acid and diluted 30% tri-butyl phosphate in the presence of simple hydroxamic acids. Solvent Extr. Ion Exch. 26 (2008) 41-61. 

Die Reindarstellung gelingt durch fraktionierte Vakuumsublimation. Tetrakis(cyclopentadienyl)neptunium(IV) (C5H5)4Np, der erste reine Aromatenkomplex des Neptuniums, wurde durch Umsetzung von NpCl4 mit einer benzolischen Suspension von KC5H5 als rotbraunes Produkt dargestellt 243> ... 

Moskvin, A. I. Complex formation by neptunium(IV) and pluto-nium(IV) in nitrate solutions, Russ. J. Inorg. Chem., 16, 405 (1971). 

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