At Fernald, a former uranium reprocessing plant outside Cincinnati, 2 million cubic yards of soil have been contaminated with uranium. Unless this soil can be cleaned, it will have to be stored at a low-level waste site. Researchers are currently seeking ways of remediating this soil without harming the soil`s matrix. This work focused on developing a chelation extraction system to remove uranium from soil. Preliminary investigations of chelators indicated that tiron (1,2-dihydroxy-3,5-benzendisulfonic acid) is able to mobilize even highly insoluble forms of uranium. Coordination chemistry principles predict that when the predominate form of uranium in the Fernald soils, U(VI), is reduced to U(IV) confirmed that the extraction capabilities of tiron were greatly enhanced by the presence of reductants. By optimizing experimental parameters for the tiron-reductant system, the authors removed 99% of uranium deposited through product spills and 90% of uranium deposited as incinerator fall out. The tiron-reductant system provides a simple, efficient method for remediation of uranium contaminated soil.

Accurate predictions of actinide and fission product migration in the geosphere are critically dependent on identification of the biological, chemical and physical processes which affect actinide mobility in soil and water. Siderophores are low molecular weight iron chelators produced by microbes in response to low availability of soluble iron. Because of the similarities between iron(III) and tetravalent actinides, and the prevalence of siderophore-producing microbes in soil, there is strong likelihood that siderophores may also bind actinides, thereby influencing their mobility in the environment. In order to begin to assess the potential importance of siderophore-mediated actinide mobility, we have determined rate constants for solubilization of hydrous plutonium oxide by the siderophores enterobactin and desferrioxamine B and selected carboxylate, amino polycarboxylate, and catecholate ligands. The measured rate constants for solubilization of insoluble actinide oxides show that siderophores are extremely effective in solubilizing actinides; on a per molecule basis, enterobactin is approximately 10(3) times more effective than the other chelators tested in increasing the rate of solubilization of hydrous plutonium oxide. Notably, ferric-siderophore complexes are more effective in solubilizing actinide oxides than the siderophores in the absence of iron. These results suggest that siderophores have the potential to mobilize actinides in the environment.

[Th(C17H13N2O2)2(NO3)2(C18H15OP)2], M(r) = 1467, orthorhombic, Pcan, a = 11.619 (10), b = 23.721 (10), c = 25.243 (4) angstrom, V = 6957.33 angstrom 3, Z = 4 D(x) = 1.40 g cm-3, lambda-(Mo K-alpha) = 0.71069 angstrom, mu = 23.2 cm-1, F(000) = 2936, T = 298 K, R = 0.058 for 2547 reflections with I greater-than-or-equal-to 2-sigma-(I). The crystal is composed of discrete molecules containing a thorium ion coordinated to ten O atoms from two bidentate benzoyl pyrazolone anions, two bidentate nitrate anions, and two triphenylphosphine oxide molecules.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxygen transfer from SO2: formation of (.eta.5-C5Me5)Ru(CO)2SO3H and [(.eta.5-C5Me5)Ru(CO)2]2(.mu.-S2O3) from the reaction of SO2 with (.eta.5-C5Me5)Ru(CO)2HKimberly A. Kubat-Martin, Gregory J. Kubas, and R. R. RyanCite this: Organometallics 1989, 8, 8, 1910–1915Publication Date (Print):August 1, 1989Publication History Published online1 May 2002Published inissue 1 August 1989https://pubs.acs.org/doi/10.1021/om00110a013https://doi.org/10.1021/om00110a013research-articleACS PublicationsRequest reuse permissionsArticle Views63Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Reaction of U(BH4)3·nTHF with Cp*2Th(PPh2)2 in a THF/toluene solution containing NaCl resulted in isolation of the novel tetrahydroborate complex [Na(THF)6][Cp*U(BH4)3]2, Cp*=C5Me5. The complex crystallizes in the space group P1 with cell parameters of a=11.110(3), b=15.140(3), c= 17.856(3) Å, α=88.27(1), β=74.49(2) and γ= 85.42(2)o, Z=2 and Dcalc=1.49 g/cm3. The unit cell contains two crystallographically independent uranium atoms in general positions, each coordinated by three tridentate, hydrogen-bridged BH4− groups and one η5-pentamethylcyclopentadienyl ligand. Two Na(THF)6+ cations, which occupy centers of crystallographic symmetry, complete the structure. Metrical parameters are not significantly different between the two independent uranium centers (av. UB distances 2.61 Å) or the two independent sodium containing cations. Crystallographically independent Cp*U(BH4)3 moieties pack to form two separate chains parallel to the crystallographic a axis. The stoichiometry and accompanying black color for the crystal suggest a mixed-valent charge transfer compound for which the average uranium oxidation state is 3.5. An unexpected Cp* transfer from thorium to uranium is also noted in the reaction chemistry.

AbstractStudies show that the fate of H2 addition to the unsaturated, air‐sensitive 16‐electron precursors (III), obtained according to the scheme, rests primarily on the basicity of the metal center as dictated by the electron‐donating ability of the ancillary phosphine ligands.