In Situ Spectroscopic Analysis and Quantification of [Tc(CO)] in Hanford Tank Waste.

The quantitative conversion of nonpertechnetate [Tc(CO)] species in nuclear waste storage tank 241-AN-102 at the Hanford Site is demonstrated. A waste sample containing the [Tc(CO)] species is added to a developer solution that rapidly converts the nonemissive species into a luminescent complex, which is detected spectroscopically. This method was first demonstrated using a [Tc(CO)] sample of nonwaste containing matrix to determine a detection limit (LOD), resulting in a [Tc(CO)] LOD of 2.

Crystallographic and Spectroscopic Characterization of Americium Complexes Containing the Bis[(phosphino)methyl]pyridine-1-oxide (NOPOPO) Ligand Platform.

The crystal structures of americium species containing a common multifunctional phosphine oxide ligand, reported for its ability to extract f elements from acidic solutions, namely, 2,6-[PhP(O)CH]CH-NO, L, were finally determined after over three decades of separations studies involving these species and their surrogates. The molecular compounds Am(L)(NO), Am 1:1, and [Am(L)(NO)][2(NO)], Am 2:1, along with their neodymium and europium analogues, were synthesized and characterized using single-crystal X-ray crystallography, attenuated total reflectance Fourier transform infrared spectroscopy, and luminescence spectroscopy to provide a comprehensive comparison with new and known analogous complexes.

In Situ Quantification of [Re(CO)] by Fluorescence Spectroscopy in Simulated Hanford Tank Waste.

A pretreatment protocol is presented that allows for the quantitative conversion and subsequent in situ spectroscopic analysis of [Re(CO)] species in simulated Hanford tank waste. In this test case, the nonradioactive metal rhenium is substituted for technetium (Tc-99), a weak beta emitter, to demonstrate proof of concept for a method to measure a nonpertechnetate form of technetium in Hanford tank waste. The protocol encompasses adding a simulated waste sample containing the nonemissive [Re(CO)] species to a developer solution that enables the rapid, quantitative conversion of the nonemissive species to a luminescent species which can then be detected spectroscopically.

Oxidation reactivity channels for 2-(pyridin-2-yl)-N,N-diphenylacetamides.

Synthetic routes to 2-(pyridin-2-yl)-N,N-diphenylacetamide and 2-(6-methylpyridin-2-yl)-N,N-diphenyl-acetamide are described along with results from the chemical oxidation of these compounds with peracetic acid, m-chloroperbenzoic acid, and OXONE. In each case, oxidations generate four products in varying amounts depending on the oxidant and reaction conditions. Each product has been characterized by spectroscopic methods and the molecular structures of several of the new compounds have been confirmed by X-ray crystallography.

Synthesis and lanthanide coordination properties of new 2,6-bis(N-tert-butylacetamide)pyridine and 2,6-bis(N-tert-butylacetamide)pyridine-N-oxide ligands.

The compound 2,6-bis(N-tert-butylacetamide)pyridine (2) was obtained via a Ritter synthesis, and oxidation with oxone provided the title pyridine-N-oxide (3). The compounds were characterized by spectroscopic methods, and the molecular structure of the N-oxide was determined by single-crystal X-ray diffraction methods. The coordination chemistry with Eu(NO3)3 was examined by using 1:1 and 2:1 ligand/Eu ratios, and a single-crystal X-ray analysis for Eu(3)(NO3)3(H2O) was completed.

A three-dimensional framework structure constructed from 2-(2-pyridyl-N-oxide) ethylphosphonic acid and Nd(III).

A multistep synthesis for 2-(2-pyridyl-N-oxide) ethylphosphonic acid 6-H2 is described along with its spectroscopic (IR, NMR) data and a single-crystal X-ray diffraction structure analysis. Combination of the ligand with Nd(OH)3 results in the formation of a complex Nd(6-H)3. Single-crystal X-ray diffraction analysis reveals a three-dimensional crystal network generated by hydrogen-bonded chains along the crystallographic c axis.

Solution and structural investigations of ligand preorganization in trivalent lanthanide complexes of bicyclic malonamides.

This report describes an investigation into the coordination chemistry of trivalent lanthanides in solution and the solid state with acyclic and preorganized bicyclic malonamide ligands. Two experimental investigations were performed: solution binding affinities were determined through single-phase spectrophotometric titrations and the extent of conformational change upon binding was investigated with single-crystal X-ray crystallography. Both experimental methods compare the bicyclic malonamide (BMA), which is designed to be preorganized for binding trivalent lanthanides, to an analogous acyclic malonamide.

Bicyclic and acyclic diamides: comparison of their aqueous phase binding constants with Nd(III), Am(III), Pu(IV), Np(V), Pu(VI), and U(VI).

This report describes affinity measurements for two, water-soluble, methyl-alkylated diamides incorporating the malonamide functionality, N,N,N',N' tetramethylmalonamide (TMMA) and a bicyclic diamide (1a), toward actinide metal cations (An) in acidic nitrate solutions. Ligand complexation to actinides possessing oxidation states ranging from +3 to +6 was monitored through optical absorbance spectroscopy, and formation constants were obtained from the refinement of the spectrophotometric titration data sets. Species analysis gives evidence for the formation of 1, 4, 1, and 2 spectrophotometrically observable complexes by TMMA to An(III, IV, V, and VI), respectively, while for 1a, the respective numbers are 3, 4, 2, and 2.

Temperature and isotope substitution effects on the structure and NMR properties of the pertechnetate ion in water.

The uniquely well-resolved (99)Tc NMR spectrum of the pertechnetate ion in liquid water poses a stringent test of the accuracy of ab initio calculations. The displacement of the (99)Tc chemical shift as a function of temperature has been measured over the range 10-45 degrees C for the three isotopomers Tc((16)O)(4)(-), Tc((16)O)(3)((18)O)(-), and Tc((16)O)(3)((17)O)(-) at natural oxygen isotope abundance levels, and in addition the temperature dependence of the Tc-O scalar coupling was determined for the Tc((16)O)(3)((17)O)(-) isotopomer. Values for these parameters were computed using relativistic spin-orbit density functional theory with an unsolvated ion approximation and with treatments of the solvated ion based on the COnductor-like Screening MOdel (COSMO) approach.

Hydrogen bonded framework structures constructed from 2-(pyridyl N-oxide) methylphosphonic acid ligands and erbium(III).

Syntheses for 2-(pyridyl N-oxide) methylphosphonic acid, 1-H, and 2-(pyridyl N-oxide) hydroxymethylphosphonic acid, 4-H, are described, and the crystal structures of both ligands are presented. Combination of these ligands with freshly prepared erbium hydroxide results in the formation of the isostructural complexes Er(L(-))(3)(LH).8H(2)O.

Large-scale purification of 90Sr from nuclear waste materials for production of 90Y, a therapeutic medical radioisotope.

A major limitation on the supply of the short-lived medical isotope 90Y (t1/2 = 64 h) is the available quantity of highly purified 90Sr generator material. A radiochemical production campaign was therefore undertaken to purify 1,500 Ci of 90Sr that had been isolated from fission waste materials. A series of alkaline precipitation steps removed all detectable traces of 137Cs, alpha emitters, and uranium and transuranic elements.

Deliberate design of ligand architecture yields dramatic enhancement of metal ion affinity.

Evaluation of the malonamide substructure with respect to binding site preorganization and complementarity for lanthanide metal ions suggests a new ligand architecture specifically designed to enhance lanthanide ion affinity. Consideration of conformational reorganization, restricted bond rotation, and donor group orientation suggests that typical malonamide structures, for example, N,N,N'N'-tetrahexylpropane-1,3-diamide (1), N,N'-dibutyl-N,N'-dimethyl-2-tetradecylpropane-1,3-diamide (2), or N,N,N'N'-tetramethylpropane-1,3-diamide (6), are poorly organized for metal ion complexation. Molecular mechanics analyses show that the unfavorable enthalpic and entropic terms are eliminated by the use of the novel bicyclic architecture found in 3,9-diaza-3,9-dimethylbicyclo[4.

Coordination of Lanthanide Nitrates with N,N,N',N'-Tetramethylsuccinamide.

Two compound classes have been identified from the reaction of trivalent lanthanide nitrates with tetramethylsuccinamide (TMSA). The nature of these Ln-TMSA compounds has been examined in the solid phase by thermogravimetric analysis (TGA) and single-crystal X-ray diffraction and in solution by infrared spectroscopy. Isostructural, 10-coordinate compounds with a 2:1 TMSA:Ln stoichiometry were found for the lanthanides La and Ce.