Uranium chloride complexes

Tri-n-butyl phosphate, ( -C4H9)3P04. This solvent is useful for the extraction of metal thiocyanate complexes, of nitrates from nitric acid solution (e.g. cerium, thallium, and uranium), of chloride complexes, and of acetic acid from aqueous solution. In the analysis of steel, iron(III) may be removed as the soluble iron(III) thiocyanate . The solvent is non-volatile, non-flammable, and rapid in its action. 

Uranium(IV) chloride adducts of Ph2SO have been isolated (73) of the type [U(Ph2S0)2Cl4]-nH20, and infrared measurements show the sulfoxide to be O-bonded. Analogous complexes of diphenyl sulfone could not be synthesized (251). 

It can be shown that the virial type of activity coefficient equations and the ionic pairing model are equivalent, provided that the ionic pairing is weak. In these cases, it is in general difficult to distinguish between complex formation and activity coefficient variations unless independent experimental evidence for complex formation is available, e.g., from spectroscopic data, as is the case for the weak uranium(VI) chloride complexes. It should be noted that the ion interaction coefficients evaluated and tabulated by Cia-vatta [10] were obtained from experimental mean activity coefficient data without taking into account complex formation. However, it is known that many of the metal ions listed by Ciavatta form weak complexes with chloride and nitrate ions. This fact is reflected by ion interaction coefficients that are smaller than those for the noncomplexing perchlorate ion (see Table 6.3). This review takes chloride and nitrate complex formation into account when these ions are part of the ionic medium and uses the value of the ion interaction coefficient (m +,cio4) for (M +,ci ) (m +,noj)- Io... 

The reaction of thorium and uranium triscyclopentadienide chloride with Grignard and lithium reagents has also led to a variety of thermally stable alkyls, aryls and allyls. These complexes will be discussed in a later part of this review. 

The question of the mode of bonding of the cyclopentadienyl rings in complexes of the type U(C5Hs)sX was settled by the structural determination of tris(ben-zylcyclopentadienide)uranium(IV) chloride (69). The structure as viewed down... 

Figure 6 Absorption spectra of uranium(IV)-chloride complexes in solution and the anion exchanger in equilibrium with this solution (from Ref 11) coordination of the resin phase complex (from Ref 29) A 10 M HCl solution of U(IV) B AG 1-X8 equilibrated with solution A O experimental plot -------theo-...

A solution of uranium (IV) chloride and an olefin (stilbene, diphenylethylene, or acenaphthylene) in tetrahydrofuran (THF) can be reduced by pulse radiolysis to give U(III) (246). The reaction may proceed through an anionic complex. 

The complexes [ N[CH2CH2NSiMc3]3 AnCl]2 (An = Th, U) were first reported the molecular structure of the uranium complex demonstrated it was dimeric in the solid state. The chloride ligand may be substituted, and derivatives incorporating cyclopentadienyl, borohydride, alkoxide, amide, and diazabutadiene derivatives have been characterized. Attempts to alkylate the... 

In the assessment of the refining performance of uranium, systematic data has been reported for the chemical properties of uranium complex in various alkali chlorides such as LiCl-RbCl and LiCl-CsCl mixtures [3-5], Information on the coordination circumstance of solute ions is also important since it should be correlated with stability. The polarizing power of electrolyte cations controls the local structure around neodymium trivalent Nd " " as an example of f-elements and the degree of its distortion from octahedral symmetry is correlated with thermodynamic properties of NdClg " complex in molten alkali chlorides [6]. On the other hand, when F coexists with Cr in melts, it is well-known that the coordination circumstances of solute ions are drastically changed because of the formation of fluoro-complexes [7-9]. A small amount of F stabilizes the higher oxidation states of titanium and induces a negative shift in the standard potentials of the Ti(IV)ITi(ni) and Ti(III)ITi(II) couples [7, 8], The shift in redox potentials sometimes causes specific electrochemical behavior, for example, the addition of F to the LiCl-KCl eutectic leads to the disproportionation of americium Am into Am " and Am metal [9],... 

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