Plutonium coordination chemistry

Coordination chemistry, 24 38 self-assembly and, 24 61 Coordination complexes thorium, 24 763-770 plutonium, 19 694-698 uranium, 25 434-437 Coordination compounds, 7 573-606 8 84-85... 

The importance of hydroxypyridinones in connection with the decorporation of plutonium (Section IV.C.7) and the similarities between the coordination chemistries of early actinides and lanthanides... 

The coordination chemistry and distribution of plutonium in the body is similar to that of iron and desferrioxamine can mobilize 239Pu from most of the organs. This fact makes the drug important for safety in the nuclear industry. 

The discovery of nuclear fission in 1938 proved the next driver in the development of coordination chemistry. Uranium-235 and plutonium-239 both undergo fission with slow neutrons, and can support neutron chain reactions, making them suitable for weaponization in the context of the Manhattan project. This rapidly drove the development of large-scale separation chemistry, as methods were developed to separate and purify these elements. While the first recovery processes employed precipitation methods (e.g., the bismuth phosphate cycle for plutonium isolation). 

All early actinides from thorium to plutonium possess a stable +4 ion in aqueous solution this is the most stable oxidation state for thorium and generally for plutonium. The high charge on tetravalent actinide ions renders them susceptible to solvation, hydrolysis, and polymerization reactions. The ions are readily hydrolyzed, and therefore act as Bronsted acids in aqueous media, and as potent Lewis acids in much of their coordination chemistry (both aqueous and nonaqu-eous). Ionic radii are in general smaller than that for comparable trivalent metal cations (effective ionic radii = 0.96-1.06 A in eight-coordinate metal complexes), but are still sufficiently large to routinely support high coordination numbers. 

Burns, C. J. Sattelberger, A. P. Organometallic and Nonaqueous Coordination Chemistry. In Advances in Plutonium Chemistry American Nuclear Society, La Grange Park, IL 2002. 

The coordination chemistry of tetravalent cerium is in many aspects very similar to the coordination chemistry of tetravalent plutonium. The ionic radius of Ce" " (0.94 A) is within the experimental error identical to the ionic radius of Pu + (Shannon and Prewitt, 1969). Due to the similarity in the charge-to-ionic size ratio, the complex formation constants of tetravalent cerium are essentially the same as those of tetravalent plutonium. Complex formation causes for the two metal systems the same shift of the redox potential. 

Chart 3. Ligands used for complex formation with cerium(IV) in model studies of plutonium(IV) coordination chemistry (a) 1,2-dihydroxybenzene (catechol) (b) 3,5-disulfonate-1,2-dihydroxybenzene (tiron) (c) l-methyl-3-hydroxy-2(l//)-pyridinone (Me-3,2-HOPO) (d) PR-Me-3,2-HOPO (e) 5LO-Me-3,2-HOPO (f) 5LI-Me-3,2-HOPO (g) A,A -diethyl-2,3-dihydroxyterephthalamide (H2ETAM). The nomenclature of the HOPO ligands is that of Raymond and coworkers (Xu et al., 2000). 

Several cerium(IV) complexes of various bidentate and tetradentate hydroxypyrodinonate (HOPO) complexes have been studied as model compounds for plutonium(IV) complexes (Xu et al., 2000). Bidentate HOPO monoanions are isolelectronic with catecholate dianions and they display a similar complex formation behavior towards cerium(IV) ions. However, HOPO ligands are more acidic and form stable complexes with cerium(IV) at lower pH values than catechol. The tetradentate ligands form more stable complexes than the corresponding bidentate ligands. New types of chelators for cerium(IV) and pluto-nium(IV) are the 2,3-dihydroxyterephthalamides (Gramer and Raymond, 2004 Xu et al., 2004). Some authors have made comparisons between the coordination chemistry and the redox behavior of cerium and berkelium (Lebedev et al., 1975 Milyukova et al., 1980 Yakovlev et al., 1982). 

Very recent results are included, for instance, the chemistry of neptunium and plutonium, cyclooctate-traene, tropolone, the theory of colour, etc, and the coordination of data from many chemical fields often throws new light on well-known facts. This is a hook which will well repay the reader s effort be he student, teacher or practising chemist—by a new insight into many aspects of chemistry. 

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