Laser-Induced Thermal Decomposition of Uranium Coordination Compounds with Non-oxidic Ligands to Produce Nitride and Carbide Materials.

The production of ceramics from uranium coordination compounds can be achieved through thermal processing if an excess amount of the desired atoms (i.e., C or N), or reactive gaseous products (e.

Unconventional Pathways to Carbide Phase Synthesis via Thermal Decomposition of UI(1,4-dioxane).

UI(1,4-dioxane) was subjected to laser-based heating─a method that enables localized, fast heating ( > 2000 °C) and rapid cooling under controlled conditions (scan rate, power, atmosphere, etc.)─to understand its thermal decomposition. A predictive computational thermodynamic technique estimated the decomposition temperature of UI(1,4-dioxane) to uranium (U) metal to be 2236 °C, a temperature achievable under laser irradiation.

Unsaturated Sulfur Crown Ethers Can Extract Mercury(II) and Show Promise for Future Copernicium(II) Studies: A Combined Experimental and Computational Study.

The unsaturated hexathia-18-crown-6 (UHT18C6) molecule was investigated for the extraction of Hg(II) in HCl and HNO media. This extractant can be directly compared to the recently studied saturated hexathia-18-crown-6 (HT18C6). The default conformation of the S lone pairs in UHT18C6 is endodentate, where the pocket of the charge density, according to the crystal structures, is oriented toward the center of the ring, which should allow better extraction for Hg(II) compared to the exodentate HT18C6.

Advancing understanding of actinide(iii) (Ac, Am, Cm) aqueous complexation chemistry.

The positive impact of having access to well-defined starting materials for applied actinide technologies - and for technologies based on other elements - cannot be overstated. Of numerous relevant 5f-element starting materials, those in complexing aqueous media find widespread use. Consider acetic acid/acetate buffered solutions as an example.

Thorium chelators for targeted alpha therapy: Rapid chelation of thorium-226.

One of the main challenges in targeted alpha therapy is assuring delivery of the α-particle dose to the targeted cells. Thus, it is critical to identify ligands for α-emitting radiometals that will form complexes that are very stable, both in vitro and in vivo. In this investigation, thorium-227 (t = 18.

A Solid-State Support for Separating Astatine-211 from Bismuth.

Increasing access to the short-lived α-emitting radionuclide astatine-211 (At) has the potential to advance targeted α-therapeutic treatment of disease and to solve challenges facing the medical community. For example, there are numerous technical needs associated with advancing the use of At in targeted α-therapy, e.g.

Investigation of a tellurium-packed column for isolation of astatine-211 from irradiated bismuth targets and demonstration of a semi-automated system.

Astatine-211 is an attractive radionuclide for use in targeted alpha therapy of blood-borne diseases and micrometastatic diseases. Efficient isolation methods that can be adapted to robust automated At isolation systems are of high interest for improving the availability of At. Based on the early studies of Bochvarova and co-workers involving isolation of At from irradiated thorium targets, we developed a method for At isolation from bismuth targets using tellurium-packed columns.

Large-Scale Production of Te and Sb for Radiopharmaceutical Applications.

Radionuclides find widespread use in medical technologies for treating and diagnosing disease. Among successful and emerging radiotherapeutics, Sb has unique potential in targeted therapeutic applications for low-energy electron-emitting isotopes. Unfortunately, developing Sb-based drugs has been slow in comparison to other radionuclides, primarily due to limited accessibility.

The coordination chemistry of Cm, Am, and Ac in nitrate solutions: an actinide L-edge EXAFS study.

Understanding actinide(iii) (An = Cm, Am, Ac) solution-phase speciation is critical for controlling many actinide processing schemes, ranging from medical applications to reprocessing of spent nuclear fuel. Unfortunately, in comparison to most elements in the periodic table, An speciation is often poorly defined in complexing aqueous solutions and in organic media. This neglect - in large part - is a direct result of the radioactive properties of these elements, which make them difficult to handle and acquire.

A series of dithiocarbamates for americium, curium, and californium.

Characterizing how actinide properties change across the f-element series is critical for improving predictive capabilities and solving many nuclear problems facing our society. Unfortunately, it is difficult to make direct comparisons across the 5f-element series because so little is known about trans-plutonium elements. Results described herein help to address this issue through isolation of An(S2CNEt2)3(N2C12H8) (Am, Cm, and Cf).

A Pseudotetrahedral Uranium(V) Complex.

A series of uranium amides were synthesized from N, N, N-cyclohexyl(trimethylsilyl)lithium amide [Li][N(TMS)Cy] and uranium tetrachloride to give U(NCySiMe) (Cl), where x = 2, 3, or 4. The diamide was isolated as a bimetallic, bridging lithium chloride adduct ((UCl(NCyTMS))-LiCl(THF)), and the tris(amide) was isolated as the lithium chloride adduct of the monometallic species (UCl(NCyTMS)-LiCl(THF)). The tetraamide complex was isolated as the four-coordinate pseudotetrahedron.

Redox-Active vs Redox-Innocent: A Comparison of Uranium Complexes Containing Diamine Ligands.

Uranium complexes (DAE)U(THF) (1-DAE) and CpU(DAE) (2-DAE) (DAE = [ArN-CHCH-NAr]; Ar = 2,4,6-trimethylphenyl (Mes)), bearing redox-innocent diamide ligands, have been synthesized and characterized for a full comparison with previously published, redox-active diimine complexes, (DAB)U(THF) (1-DAB) and CpU(DAB) (2-DAB) (DAB = [ArN═C(Me)C(Me)═NAr]; Ar = Mes). These redox-innocent analogues maintain an analogous steric environment to their redox-active ligand counterparts to facilitate a study aimed at determining the differing electronic behavior around the uranium center. Structural analysis by X-ray crystallography showed 1-DAE and 2-DAE have a structural environment very similar to 1-DAB and 2-DAB, respectively.

Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA); Synthesis and Structure of MTTA (M = Zr, Hf, Ce, Th, U, Np, Pu) and M(TTA) (M = Ce, Nd, Sm, Yb).

Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.

Evaluating the electronic structure of formal Ln ions in Ln(CHSiMe) using XANES spectroscopy and DFT calculations.

The isolation of [K(2.2.2-cryptand)][Ln(CHSiMe)], formally containing Ln, for all lanthanides (excluding ) was surprising given that +2 oxidation states are typically regarded as inaccessible for most 4f-elements.

Polyoxovanadate-Alkoxide Clusters as a Redox Reservoir for Iron.

Inspired by the multielectron redox chemistry achieved using conventional organic-based redox-active ligands, we have characterized a series of iron-functionalized polyoxovanadate-alkoxide clusters in which the metal oxide scaffold functions as a three-dimensional, electron-deficient metalloligand. Four heterometallic clusters were prepared through sequential reduction, demonstrating that the metal oxide scaffold is capable of storing up to four electrons. These reduced products were characterized by cyclic voltammetry, IR, electronic absorption, and H NMR spectroscopies.

Synthesis and Characterization of the Actinium Aquo Ion.

Metal aquo ions occupy central roles in all equilibria that define metal complexation in natural environments. These complexes are used to establish thermodynamic metrics (i.e.

Examining the Effects of Ligand Variation on the Electronic Structure of Uranium Bis(imido) Species.

Arylazide and diazene activation by highly reduced uranium(IV) complexes bearing trianionic redox-active pyridine(diimine) ligands, [CpU(PDI)] (1-Cp), Cp*U(PDI)(THF) (1-Cp*) (Cp = 1-(7,7-dimethylbenzyl)cyclopentadienide; Cp* = η-1,2,3,4,5-pentamethylcyclopentadienide), and Cp*U(Bu-PDI) (THF) (1-Bu) (2,6-((Mes)N═CMe)2-p-R-CHN, Mes = 2,4,6-trimethylphenyl; R = H, PDI; R = C(CH), Bu-PDI), has been investigated. While 1-Cp* and 1-Cp readily reduce NR (R = Ph, p-tolyl) to form trans-bis(imido) species, CpU(NAr)(PDI) (Ar = Ph, 2-Cp; Ar = p-Tol, 3-Cp) and Cp*U(NPh)(PDI) (2-Cp*), only 1-Cp* can cleave diazene N═N double bonds to form the same product. Complexes 2-Cp*, 2-Cp, and 3-Cp are uranium(V) trans-bis(imido) species supported by neutral [PDI] ligands formed by complete oxidation of [PDI] ligands of 1-Cp and 1-Cp*.

Comparing the 2,2'-Biphenylenedithiophosphinate Binding of Americium with Neodymium and Europium.

Advancing our understanding of the minor actinides (Am, Cm) versus lanthanides is key for developing advanced nuclear-fuel cycles. Herein, we describe the preparation of (NBu4 )Am[S2 P((t) Bu2 C12 H6 )]4 and two isomorphous lanthanide complexes, namely one with a similar ionic radius (i.e.

Spectroscopic and computational investigation of actinium coordination chemistry.

Actinium-225 is a promising isotope for targeted-α therapy. Unfortunately, progress in developing chelators for medicinal applications has been hindered by a limited understanding of actinium chemistry. This knowledge gap is primarily associated with handling actinium, as it is highly radioactive and in short supply.

Redox Non-Innocence of Nitrosobenzene at Nickel.

Nitrosobenzene (PhNO) serves as a stable analogue of nitroxyl (HNO), a biologically relevant, redox-active nitric oxide derivative. Capture of nitrosobenzene at the electron-deficient β-diketiminato nickel(I) complex [(i) Pr2 NNF6 ]Ni results in reduction of the PhNO ligand to a (PhNO)(./-) species coordinated to a square planar Ni(II) center in [(i) Pr2 NNF6 ]Ni(η(2) -ONPh).

Monomers, Dimers, and Helices: Complexities of Cerium and Plutonium Phenanthrolinecarboxylates.

The reaction of Ce(III) or Pu(III) with 1,10-phenanthroline-2,9-dicarboxylic acid (PDAH2) results in the formation of new f-element coordination complexes. In the case of cerium, Ce(PDA)(H2O)2Cl·H2O (1) or [Ce(PDAH)(PDA)]2[Ce(PDAH)(PDA)] (2) was isolated depending on the Ce/ligand ratio in the reaction. The structure of 2 is composed of two distinct substructures that are constructed from the same monomer.