Transplutonium complexes oxides

Transplutonium(VI) complexes aqua,3,1220 carbonates, 3, 1220 carboxylates chelating, 3, 1220 halogens, 3,1220 monocarboxylates, 3,1220 nitrato, 3,1220 oxides, 3,1220 oxoanions, 3, 1220 Transport cations... 

Tricyclopentadienide complexes of many of the actinides are known (Ac = Th, U, Pu, Am, Cm, Bk, Cf). Indeed, these are the only cyclopentadienide complexes known for the transplutonium elements, where -(-3 is the most stable oxidation state. The transplutonium elements were all prepared by a microchemical procedure which utilized a melt of biscyclopentadienyl beryllium (6) according to ... 

Table 90 Complexes of Transplutonium Actinide(III) /3-Ketoenolates with P-Oxides...

The oxidation-reduction behavior of plutonium is described by the redox potentials shown in Table I. (For the purposes of this paper, the unstable and environmentally unimportant heptavalent oxidation state will be ignored.) These values are of a high degree of accuracy, but are valid only for the media in which they are measured. In more strongly complexing media, the potentials will change. In weakly complexing media such as 1 M HClOq, all of the couples have potentials very nearly the same as a result, ionic plutonium in such solutions tends to disproportionate. Plutonium is unique in its ability to exist in all four oxidation states simultaneously in the same solution. Its behavior is in contrast to that of uranium, which is commonly present in aqueous media as the uranyl(VI) ion, and the transplutonium actinide elements, which normally occur in solution as trlvalent... 

Extraction processes (TRUEX, PUREX, Talspeak, DIAMEX, PARC, etc.) generally involve complexation of transplutonium elements by alkyl phosphines, phosphine oxides, phosphoric acids, carbamoyl phosphonates, diamides, and thiophosphinates in aqueous/organic extractions, within derivatized solid supports, or on coated particles. There are excellent reviews of the processes and significant complexes by Mathur et al. and selected chapters in The Chemistry of the Actinide and Transactinide Elements to be published in 2003. " Work on the separation for nuclear waste management in the United States, France, and Russia have been reviewed. " ... 

Phosphine oxides. Few molecular complexes of trivalent transplutonium elements have been reported. Several studies examine the extraction chemistry of Am, Cm, and Bk with a combination of /3-diketones and tri-n-alkyl phosphine oxides and tiialkylphosphates. From these, compounds reported to be of the formula AnF3(R3PO) c (An = Am, Cm R = n-octyl, Bu"0) were isolated, where L = CF3COCHCOR (R = Me, CF3, Bu ). The stoichiometry of the complexes (An P=0) was not always reported. The complex Am(CF3COCHCOCF3)3[OP(OBu )3]2 is reported to be volatile at 175 °C. ... 

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 chemistry of actinide ions is generally determined by their oxidation states. The trivalent, tetravalent and hexavalent oxidation states are strongly complexed by numerous naturally occurring ligands (carbonates, humates, hydroxide) and man-made complexants (like EDTA), moderately complexed by sulfate and fluoride, and weakly complexed by chloride (7). Under environmental conditions, most uncomplexed metal ions are sorbed on surfaces (2), but the formation of soluble complexes can impede this process. With the exception of thorium, which exists exclusively in the tetravalent oxidation state under relevant conditions, the dominant solution phase species for the early actinides are the pentavalent and hexavalent oxidation states. The transplutonium actinides exist only in the trivalent state under environmentally relevant conditions. 

Transplutonium(IV) complexes, 1219 halogeno, 1219 3-ketoenolates, 1219 oxides, 1219 tetrahalides, 1219... 

Transplutonium(V) complexes, 1219 aqua,1219 carbonates, 1220 halogens, 1220 monocarboxyiates, 1220 oxalates, 1220 oxides, 1219... 

Transplutonium(VI) complexes aqua,1220 carbonates, 1220 carboxylates chelating, 1220 halogens, 1220 monocarboxyiates, 1220 nitrato, 1220 oxides, 1220 oxoanions, 1220 Triethanolamine alkali metal complexes, 23 Triethylamine, 2,2, 2"-trimethoxy-alkali metal complexes, 24 Trimolybdates, 1032 Trithioarsenates, 249 1,3,6,2-Trithioarsocane, 2-chloro-, 249 Trithioraolybdates, 1378 Trivanadates, 1027... 

In table 24 are shown the known condensed phase of actinide oxides. The similarity of the transplutonium oxides to known lanthanide type of oxides is obvious. The apparent absence of specific lanthanide-type of oxides beyond An O j (e.g., the complex phases for intermediate oxides of the lanthanides) for the actinides may be real or may merely reflect that comparable in-depth studies for them have not been undertaken. The existence of higher oxides for the actinides, Pa-Np, reflect the differences in their electronic nature, as discussed above. 

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