The Chemistry of the Actinide and Transactinide Elements

Morss, Lester R.; Edelstein, Norman M.; Fuger, J.

doi:10.1007/1-4020-3598-5

Cited by 451 publications

(11 citation statements)

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“…The actinides do not however easily yield their secrets or succumb to simple description. The opposing trends of energetic and spatial contributions to orbital mixing behavior across the 5f series, as well as the emerging prominence of scalar relativistic and spin–orbit effects in chemical behavior, yield a series unamenable to description via traditional models and resistant to predictions reliant on monotonic periodic changes. − Instead, understanding the actinides requires the synthesis of multiple theoretical models and consideration not just of ionic radius or simple rules but of real changes in bonding along the series. − Perhaps the model whose conceptual underpinnings cause the most trouble in the actinides is “covalency.” The standard dichotomy has a spectrum running between ionic and covalent bonding, where ionic bonds involve localized electrons and covalent bonds have more mixed molecular orbitals and more shared electrons which stabilize the bond by concentrating in the internuclear space. The actinides disrupt this binary, mixing 5f and ligand orbitals by energetic matching without much spatial overlap, resulting in bonds with delocalized electrons but little internuclear charge concentration.…”

Section: Introductionmentioning

confidence: 99%

Structure and Characterization of an Americium Bis(O,O’-diethyl)dithiophosphate Complex

et al. 2020

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A facile synthesis of an americium complex with a sulfur-donor ligand has been developed, allowing characterization of americium bonding from multiple perspectives via several techniques. Reaction of 243 Am with S 2 P(OEt) 2 − yields the tetrakis complex [Am(S 2 P(OEt) 2 ) 4 ] − that can be crystallized as the tetraphenylarsonium salt. Structures obtained from single crystal X-ray diffraction show bond length discrepancies from the neodymium analogue consistent with the soft-donor bond enhancement common to actinides. Solid state optical spectroscopy confirms interaction of the ligand with 5f orbitals. 31 P nuclear magnetic reflects the minor paramagnetism of Am(III). Computational investigations through CASSCF calculations, ligand-field density functional theory, and quantum chemical topological analysis allow a quantification of covalency or orbital interaction effects via total energy density and nephelauxetic parameters, both of which indicate greater covalency in the americium species than in the neodymium analogue or the americium aquo complex.

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Section: Introductionmentioning

confidence: 99%

Structure and Characterization of an Americium Bis(O,O’-diethyl)dithiophosphate Complex

et al. 2020

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“…This phenomenon is common in lanthanide and actinide systems alike, and therefore, attempts to elucidate the mechanism governing oxalate formation were not made. We only speculate that decomposition of the TBA molecules and conversion to oxalate occurred and were mediated by a combination of the acidic conditions and α radiolysis caused by the high-energy nuclear decay of the 243 Am metal centers (α = 5.277 MeV) …”

Section: Resultsmentioning

confidence: 99%

Americium Oxalate: An Experimental and Computational Investigation of Metal–Ligand Bonding

et al. 2023

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A novel actinide-containing coordination polymer, [Am(C2O4)(H2O)3Cl] (Am-1), has been synthesized and structurally characterized. The crystallographic analysis reveals that the structure is two-dimensional and comprised of pseudo-dimeric Am3+ nodes that are bridged by oxalate ligands to form sheets. Each metal center is nine-coordinate, forming a distorted capped square antiprism geometry with a C 1 symmetry, and features bound oxalate, aqua, and chloro ligands. The Am3+–ligand bonds were probed computationally using the quantum theory of atoms in molecules nd natural localized molecular orbital approaches to investigate the underlying mechanisms and hybrid atomic orbital contributions therein. The analyses indicate that the bonds within Am-1 are predominantly ionic and the 5f shell of the Am3+ metal centers does not add a significant covalent contribution to the bonds. Our bonding assessment is supported by measurements on the optical properties of Am-1 using diffuse reflectance and photoluminescence spectroscopies. The position of the principal absorption band at 507 nm (5L6′ ← 7F0′) is notable because it is consistent with previously reported americium oxalate complexes in solution, indicating similarities in the electronic structure and ionic bonding. Compound Am-1 is an active phosphor, featuring strong bright-blue oxalate-based luminescence with no evidence of metal-centered emission.

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“…The precipitation of actinides was achieved almost 50 years ago using BiPO4 by the process of co-precipitation of Pu and Np [9]. This process does not quantitatively remove any element due to solubility limitations and precipitates other metals, such as zirconium, which form insoluble phosphates.…”

Section: Resulting Waste Treatmentmentioning

confidence: 99%

The Disposal of Strippable Coatings Employed in Chemical and Radioactive Surface Decontamination

et al. 2020

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In general, to achieve surface decontamination large amounts of water are used as the main solvent in universal decontamination solutions. The used water, in order to be released in the stream flow, must be treated to eliminate the toxic substances. Strippable coatings visibly minimize the amount of waste resulting from the decontamination process. Biodegradable films based on polyvinyl alcohol were synthesized and used within this study. The polymeric coatings also contains Bentonite nano-clay (BT) that is a rheological agent, a complexing agent used to entrap the heavy metal or radioactive particles and glycerol used as an additive to give the films the proper mechanical properties. Nevertheless, the used coatings must also be disposed of in a certain way. This paper studies few methods in which strippable coatings that are presented as chemical and/or radioactive waste are treated and proposes means to reutilize used films that are or/are not contaminated, but also suggests a simplified technological process for producing such decontamination solutions.

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The Chemistry of the Actinide and Transactinide Elements

Cited by 451 publications

References 0 publications

Structure and Characterization of an Americium Bis(O,O’-diethyl)dithiophosphate Complex

Structure and Characterization of an Americium Bis(O,O’-diethyl)dithiophosphate Complex

Americium Oxalate: An Experimental and Computational Investigation of Metal–Ligand Bonding

The Disposal of Strippable Coatings Employed in Chemical and Radioactive Surface Decontamination

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