Actinide complexes ketones

The actinides have a high degree of specificity for neutral and anionic oxygen-containing organic molecules. The actinide complexes with O -donor ligands that are most widely studied include alkoxides, aryloxides amide, carboxylates, and oxalates. Complexes with alcohols, ethers, esters, ketones, aldehydes, ketoenolates, and carbamates have also been reported. 

Actinide ions form complex ions with a large number of organic substances (12). Their extractabiUty by these substances varies from element to element and depends markedly on oxidation state. A number of important separation procedures are based on this property. Solvents that behave in this way are thbutyl phosphate, diethyl ether [60-29-7J, ketones such as diisopropyl ketone [565-80-5] or methyl isobutyl ketone [108-10-17, and several glycol ether type solvents such as diethyl CeUosolve [629-14-1] (ethylene glycol diethyl ether) or dibutyl Carbitol [112-73-2] (diethylene glycol dibutyl ether). 

Only one study has suggested the formation of an actinide(IID alkoxide (-OR) compound in which R is an alkyl. A recent investigation of the reactivity of Pu wo-propoxide, prepared in situ from the reaction of Pu[N(SiMe3)2]3 and three equivalents HOPr , indicates that the trivalent alkoxide complex is an effective catalyst in the Meerwein-Ponndorf-Verley reduction of ketones by isopropanol. ... 

Compounds such as fluorinated /3-ketones have been used mainly for the extraction of lanthanides and actinides, as more effective ligands than fluorinated dithiocarbamates for complexation with f-block elements. In addition to complex formation, some analytes (e.g. tervalent lanthanides) require the presence of a small amount of water containing 5% methanol — which act as matrix and solvent modifier, respectively — for quantitative extraction [89]. Also, a synergistic effect on the SFE of actinides [90,91] and of lanthanides from cellulose [92] and acid solutions [93] was observed when using a mixture of tributylphosphate (TBT) and a fluorinated /3-diketone. The effect was ascribed to competition of TBT with the matrix for the unoccupied coordination sites of lanthanides and actinides. Thus, the formation of adducts with the complexes of these analytes with fluorinated /3-ketones in supercritical COj facilitates their removal from the solid matrix. 

Neutral extractants may be used for uncharged metal complexes, ionic salts, and strong acids. Examples include ethers such as diethylether and diisopropylether ketones such as methylisobutyl ketone (MIBK or hexone) and neutral organophosphorous compounds such as tri-n-butylphosphate (TBP), tri-n-octylphosphine oxide (TOPO), triphenylphosphate (TPP), and triphenyphosphine oxide (TPPO). Such neutral extractants have long been used for extracting actinides and lanthanides from nitric acid solutions. 

The chelate complexes formed by acetylacetone (pentane-2,4-dione, PD) with tetravalent actinides crystallize in two modifications [449]. In the a form, which is exhibited by the Th(PD)4 and U(PD)4, the eight ketonic O atoms form a dodecahedron around the metal atom and in the P form, also adopted by these compounds and by Pa(PD)4 [450], Np(PD)4, and Pu(PD)4, the arrangement of O atoms is antiprismatic. In each modification there are discrete M(PD)4 molecules, and the four PD ligands are each planar and attached in a bidentate fashion to the metal. The same arrangement is adopted in Th(PD)4 (C6H6) [451], but in the trifluorinated species, Th(Cp3C4H402)4-H20, the water is included to make coordination 9 [452]. 

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