23288-61-1Relevant articles and documents
Kinetics of technetium reactions: XV. Tc(IV) oxidation with persulfate ions in HClO4 solution
Koltunov,Gomonova,Koltunov
, p. 163 - 167 (2005)
Tc(IV) is oxidized with persulfate ions in HClO4 solution by reactions with both S2O82- ion and product of its thermal decomposition, Caro acid, H2SO5. The reaction rate at 35°C and solutio
Syntheses and characterization of dicarbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media: Spectroscopic, structural, and DFT analyses
Schibli, Roger,Marti, Niklaus,Maurer, Patrick,Spingler, Bernhard,Lehaire, Marie-Line,Gramlich, Volker,Barnes, Charles L.
, p. 683 - 690 (2005)
This work describes new synthetic routes to produce mixed carbonyl-nitrosyl complexes of technetium(I) and rhenium(I) in aqueous media. NaNO2, NOHSO4, and NO2(g) have been used to produce in situ nitrous acid as the primary source of NO+. Starting from the organometallic precursor fac-[MX3(CO)3]+, 1 (M = 99Tc, Re; X = Cl, Br), the formation of mixed dicarbonyl- mononitrosyl complexes was observed in aqueous hydrochloric and hydrobromic acid. Time-dependent analyses of the reactions by means of HATR-IR and 99Tc NMR spectroscopy in solution revealed the almost quantitative substitution of one CO ligand by NO+ and, thus, the formation of complexes with facial arrangement of the three π-acceptor ligands. In the case of technetium, the monomeric complex (NEt4)[TcCl 3(CO)2NO] (3a) and the dimeric, chloride-bridged, neutral complex [TcCl(μ-Cl)(CO)2NO]2 (4a) were produced. In the case of rhenium, the monomeric species (NEt4)[ReBr 2X(CO)2NO] (X = Br (3b), NO3 (5)) was solely isolated. The X-ray structure of complexes 4a and 5 are discussed. The crystallographic analyses revealed the coordination of the NO+ group trans to the terminal chloride (4a) or the bromide (5), respectively. Crystal data: complex 4a (C4Cl4N2O6Tc 2), monoclinic, Cc, a = 18.82(3) A, b = 6.103(6) A, c = 12.15(2) A, α = 90°, β = 105.8(2)°, γ = 90°, V = 1343(3) A3, Z = 4; complex 5 (C10H 20N3O6Br2Re), orthorhombic, P2 12121, a = 10.2054-(5) A, b = 12.5317(7) A, c = 13.9781(7) A, V = 1787.67(16) A3, Z = 4. The isolated complexes and their potential facial isomers have been further investigated by density functional theory (DFT) calculations. The energy differences of the isomers are relatively small; however, the calculated energies are consistent with the formation of the observed and isolated compounds. The calculated bond lengths and angles of complex 5 are in good agreement with the data determined by X-ray diffraction. Experiments on the no-carrier-added level starting from fac-[99mTc(H2O) 3(CO)3]+ revealed the formation of the complex fac-[99mTcCl(H2O)2(CO)2NO] + in reasonable good yields. This aqueous-based, synthetic approach will enable the future evaluation of this novel, low-valent metal precursor for potential use in radiopharmacy.
Interaction of neptunium and technetium with UO2+x
Batuk,Kalmykov,Petrov,Teterin,Zakharova
, p. 409 - 414 (2007)
Interaction of uranium dioxide with highly mobile radionuclides 237Np and 99Tc was studied under oxidative conditions. Sorption of these radionuclides at different pH was measured, and the mechanism of redox reaction occurring in the course of their sorption were determined. In alkaline solution, Np(V) is reduced on the UO2+x surface and is sorbed in the form of tetravalent species. In neutral solutions, Np is sorbed in the form of Np(V). This is due to the fact that the stoichiometry of the UO2+x surface corresponds to U4O9. In acid solution, U(VI) is leached to form surface UO2. Although the free surface area of a UO2+x sample is low, the Np distribution coefficients K d at pH > 6 are relatively high: log K d > 2. Unlike Np, Tc(VII) is not reduced on the UO2+x surface. However, the sorption capacity of uranium dioxide for Tc(IV) is high.
Ianoz, Eugenia,Mantegazzi, Dominique,Lerch, Pierre,Nicolo, Francesco,Chapuis, Gervais
, p. 235 - 240 (1989)
Astheimer, L.,Schwochau, K.
, p. 240 - 241 (1967)
Synthesis, structure elucidation, and redox properties of 99Tc complexes of lacunary Wells-Dawson polyoxometalates: Insights into molecular 99Tc-metal oxide interactions
McGregor, Donna,Burton-Pye, Benjamin P.,Howell, Robertha C.,Mbomekalle, Israel M.,Lukens, Wayne W.,Bian, Fang,Mausolf, Edward,Poineau, Frederic,Czerwinski, Kenneth R.,Francesconi, Lynn C.
, p. 1670 - 1681 (2011/05/04)
The isotope 99Tc (βmax, 293.7; half-life, 2.1 × 105 years) is an abundant product of uranium-235 fission in nuclear reactors and is present throughout the radioactive waste stored in underground tanks at the Hanford and Savannah River sites. Understanding and controlling the extensive redox chemistry of 99Tc is important in identifying tunable strategies to separate 99Tc from spent fuel and from waste tanks and, once separated, to identify and develop an appropriately stable waste form for 99Tc. Polyoxometalates (POMs), nanometer-sized models for metal oxide solid-state materials, are used in this study to provide a molecular level understanding of the speciation and redox chemistry of incorporated 99Tc. In this study, 99Tc complexes of the (α2-P2W17O61)10- and (α1-P2W17O61) 10- isomers were prepared. Ethylene glycol was used as a "transfer ligand" to minimize the formation of TcO2? xH2O. The solution structures, formulations, and purity of Tc VO(α1/α2-P2W 17O61)7- were determined by multinuclear NMR. X-ray absorption spectroscopy of the complexes is in agreement with the formulation and structures determined from 31P and 183W NMR. Preliminary electrochemistry results are consistent with the EXAFS results, showing a facile reduction of the TcVO(α1-P 2W17O61)7- species compared to the TcVO(α2-P2W17O 61)7- analog. The α1 defect is unique in that a basic oxygen atom is positioned toward the α1 site, and the TcVO center appears to form a dative metal-metal bond with a framework W site. These attributes may lead to the assistance of protonation events that facilitate reduction. Electrochemistry comparison shows that the ReV analogs are about 200 mV more difficult to reduce in accordance with periodic trends.
Microwave-assisted synthesis of 3,1,2- and 2,1,8-Re(I) and 99mTc(I)-metallocarborane complexes
Green, Andrew E. C.,Causey, Patrick W.,Louie, Anika S.,Armstrong, Andrea F.,Harrington, Laura E.,Valliant, John F.
, p. 5727 - 5729 (2008/10/09)
Microwave heating was used to prepare η5-rhenium carborane complexes in aqueous reaction media. For carboranes bearing sterically demanding substituents, isomerization of the cage from 3,1,2 to 2,1,8 derivatives occurred concomitantly with complexation. Microwave heating was equally effective at the tracer level using technetium-99m, affording access to a new class of synthons for designing novel molecular imaging agents.
