Deviation between the Structural Chemistry of Barium and Radium Halides: Synthesis and Characterization of RaX·HO and RaX·2HO (X = Cl and Br).

To develop the structural chemistry of radium, the halide compounds RaX·HO and RaX·2HO (X = Cl and Br) have been synthesized and characterized and serve as benchmarks for comparisons with more complex compounds in the future. In contrast with historic reports on the structural chemistry of radium, the Ra chlorides differ from their Ba analogues. For MCl·HO (M = Ba, Ra), the variance between the metal coordination environments manifests as a small, local distortion that becomes more apparent in the extended structure.

Comparison of Americium(III) and Neodymium(III) Monothiophosphate Complexes.

Mixed-donor ligands, such as those containing a combination of O/N or O/S, have been studied extensively for the selective extraction of trivalent actinides, especially Am and Cm, from lanthanides during the recycling of used nuclear fuel. Oxygen/sulfur donor ligand combinations also result from the hydrolytic and/or radiolytic degradation of dithiophosphates, such as the Cyanex class of extractants, which are initially converted to monothiophosphates. To understand potential differences between the binding of such degraded ligands to Nd and Am, the monothiophosphate complexes [M(OPS(OEt))(HO)] (M = Nd, Am) were prepared and characterized by single-crystal X-ray diffraction and optical spectroscopy and studied as a function of pressure up to ca.

Investigation of Pressure Effects in the Bimetallic Transplutonium Tetrazolate Complexes [(An(pmtz)(HO))(μ-pmtz)](pmtz)·HO (An = Cm, Bk, and Cf).

Understanding the effects of pressure on actinide compounds is an integral part of safe nuclear waste storage in deep geologic repositories and provides a means of systematically altering the structure and properties. However, detailing how the effects of pressure evolve across the actinide series in the later elements is not typically undertaken because of the challenges of conducting research on these unstable isotopes. Here, a family of bimetallic actinide complexes, [(An(pmtz)(HO))(μ-pmtz)](pmtz)·HO (An = Cm, Bk, and Cf, pmtz = 5-(pyrimidyl)tetrazolate; , , and ), are reported and represent the first structurally characterized bimetallic berkelium and californium compounds.

Chemical Kinetics for the Oxidation of Californium(III) Ions with Select Radiation-Induced Inorganic Radicals (Cl and SO).

Despite the availability of transuranic elements increasing in recent years, our understanding of their most basic and inherent radiation chemistry is limited and yet essential for the accurate interpretation of their physical and chemical properties. Here, we explore the transient interactions between trivalent californium ions () and select inorganic radicals arising from the radiolytic decomposition of common anions and functional group constituents, specifically the dichlorine (Cl) and sulfate (SO) radical anions. Chemical kinetics, as measured using integrated electron pulse radiolysis and transient absorption spectroscopy techniques, are presented for the reactions of these two oxidizing radicals with ions.

Transformation of Mononuclear Plutonium(III) Tetrazolate Complexes into Dinuclear Complexes in the Solid State.

The salt metathesis reaction of Na(pmtz)·HO [pmtz 5-(pyrimidyl)tetrazolate] and PuBr·HO in an aqueous media leads to the formation of the mononuclear compound [Pu(pmtz)(HO)]·(3 + ) HO (, = ∼8) that is isotypic with the lanthanide compounds [Ln(pmtz)(HO)]·(3 + ) HO (Ln = Ce-Nd). Dissolution and recrystallization of in water yields the dinuclear compound {[Pu(pmtz)(HO)](μ-pmtz)}(pmtz)·14HO (), which is isotypic with the lanthanide compounds {[Ln(pmtz)(HO)](μ-pmtz)}(pmtz)·14HO (Ln = Nd and Sm). Like their nine-coordinate ionic radii, the M-O and M-N bond lengths in / and /, respectively, are within error of one another.

Co-Crystallization of Plutonium(III) and Plutonium(IV) Diglycolamides with Pu(III) and Pu(IV) Hexanitrato Anions: A Route to Redox Variants of [Pu(DGA)][Pu(NO)].

-tetramethyl diglycolamide (TMDGA), a methylated variant of the diglycolamide extractants being proposed as curium holdback reagents in advanced used nuclear fuel reprocessing technologies, has been crystallized with plutonium, a transuranic actinide that has multiple accessible oxidation states. Two plutonium TMDGA complexes, [Pu(TMDGA)][Pu(NO)] and[Pu(TMDGA)][Pu(NO)]·0.75MeOH, were crystallized through solvent diffusion of a reaction mixture containing plutonium(III) nitrate and TMDGA.

Neptunium Alkoxide Chemistry: Expanding Alkoxides to the Transuranium Elements.

Two oxo-containing neptunium(IV) -butoxides, [NpO(OBu)] () and [KNpO(OBu)] (), were synthesized using the ligand substitution between neptunium(IV) silylamides and HOBu, whereas the salt metathesis between [NpCl(DME)] (DME = dimethoxyethane) and various amounts of LiOBu resulted in the formation of oxo-free alkoxides [Np(OBu)(py)] (; py = pyridine) and [Li(THF)][Np(OBu)] (; THF = tetrahydrofuran). These complexes are the first structurally characterized neptunium(IV) alkoxides using single-crystal X-ray diffraction and solid-state absorption spectroscopy, which provide data for the development of anhydrous metal-organic neptunium chemistry.

Two Neptunium(III) Mellitate Coordination Polymers: Completing the Series Np-Cf of Trans-Uranic An(III) Mellitates.

Two neptunium(III) mellitates, Np(mell)(HO)·1.5HO () and Np(mell)(HO)·2HO (), have been synthesized from NpCl(dme) by reduction with KC and subsequent reaction with an aqueous solution of mellitic acid (Hmell). Characterization by single-crystal X-ray crystallography and UV-vis-NIR spectroscopy confirms that the neptunium is in its +3 oxidation state and both polymorphs are isostructural to the previously reported plutonium mellitates.