23288-61-1Relevant academic research and scientific papers
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
Carborane-carbohydrate derivatives - Versatile platforms for developing targeted radiopharmaceuticals
Green, Andrew E. C.,Harrington, Laura E.,Valliant, John F.
, p. 1063 - 1069 (2008)
A series of carborane-carbohydrate derivatives were prepared as model platforms for developing targeted radiopharmaceuticals in which a single ligand can be tagged with two different classes of radionuclides. A nidocarborane linked to glucose was synthesized and the cage labelled with a radiometal ( 99mTc) and a radiohalogen (125I) in good radiochemical yield. The 99mTc-metallocarborane derivative was prepared via microwave-assisted reactions, while the iodinated derivative was prepared using oxidative labelling methods in mere minutes. Fully characterized reference standards were prepared using nonradioactive rhenium and iodine and used to demonstrate that the isolated radioactive compounds were in fact the desired targets. The work reported, which is one of the rare examples of a single ligand system that can be labelled with both radiohalogens and radiometals, forms the basis of a new paradigm for developing targeted radiopharmaceuticals.
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.
Structure, stability, and biodistribution of cationic [M(CO) 3]+ (M = Re,99Tc, 99mTc) complexes with tridentate amine ligands
Haefliger, Pascal,Mundwiler, Stefan,Ortner, Kirstin,Spingler, Bernhard,Alberto, Roger,Andocs, Gabor,Balogh, Lajos,Bodo, Katalin
, p. 27 - 34 (2005)
Bifunctional chelating molecules linking the fac-[99mTc(CO) 3]+ core with targeting biomolecules are required for the development of specific diagnostic radiopharmaceuticals. Diethylenetriamine (1) and N-(pyridin-2-ylmethyl)ethane-1,2-diamine (2) both react readily with [ 99mTc(H2O)3(CO)3]+ in 0.9% saline at micromolar concentrations to form the cationic complexes [ 99mTc(1)(CO)3]+ (5) and [99mTc(2) (CO)3]+ (6) in quantitative yields. The crystal structures of the corresponding Re or 99Tc complexes were determined and exhibit in particular the small size of 5. Challenging both 99mTc complexes 5 and 6 with a 104 excess of histidine or cysteine showed no decomposition or ligand exchange after 24 hours and both compounds were also stable against reoxidation to [99mTcO4]-. In normal mice, complex 5 revealed a good and fast clearance from the blood, and most organs. Only limited accumulation in the large intestine was visible after 4 hours. Complex 6 was also excreted relatively quickly from the blood but retention was observed in some tissues after 4 h. In order to illustrate the potential of both ligands to be further functionalized, two derivatives containing potentially DNA binding functionalities, N-(2-Amino-ethyl)-N′- pyren-1-ylmethyl-ethane-1,2-diamine (3) and N-(quinolin-2-ylmethyl)ethane-1,2- diamine (4) were synthesized. The respective Re or 99Tc complexes were fully characterized. Based on these results, it appears that functionalization of biomolecules with acyclic triamine ligands is biologically relevant. Complex 5 in particular could be used to mimic a terminal amino group in, e.g., a peptide due to its small size and positive charge. Copyright
Research committee on ruthenium and technetium chemistry in PUREX system, organized by the atomic energy society of Japan
Matsumoto,Uchiya,Ozawa,Kobayashi,Shirato
, p. 219 - 224 (2003)
The paper summarizes the activity of the committee "Ruthenium and Technetium Chemistry in the PUREX System," with a focus on basic information on technetium behavior in the PUREX process, the principles of plant design, and the behavior during the final w
Synthesis and physical properties of hexakis(isothiocyanato)technetate(III) and -(IV) complexes. Structure of the [Tc(NCS)6]3- ion
Trop,Davison,Jones,Davis,Szalda,Lippard
, p. 1105 - 1110 (1980)
The reaction between ammonium thiocyanate and (NH4)2TcX6, X = Cl and Br, salts is shown to produce a mixture of red (λ 500 nm) [Tc(NCS)6]2- and air-sensitive yellow (λ 400 nm) [Tc(NCS)6]3- ions. These species were chromatographically separated and isolated as their ammonium, tetraphenylarsonium, or tetra-n-butylammonium salts. The technetium(IV) compound was also obtained through reduction of ammonium pertechnetate followed by treatment with ceric ion. Infrared, Raman, conductivity, and magnetic susceptibility data are reported for these complexes and shown to be consistent with octahedral structures. The detailed geometry of (n-Bu4N)3[Tc(NCS)6] was determined in a single-crystal X-ray diffraction study. The compound crystallizes in the cubic system, space group Pa3, with a = 24.444 (6) A? and Z = 8. The technetium atom is situated on a crystallographic threefold rotation axis. The Tc-N bond lengths are 2.04 (2) and 2.05 (2) A?, and the N-Tc-N angles range from 88.0 (6) to 92.1 (7)°, indicative of nearly perfect octahedral symmetry. The average Tc-N-C and N-C-S bond angles are 173 (2) and 177 (2)°, respectively. Voltammetric studies in acetonitrile show a reversible one-electron transfer between [Tc(NCS)6]3- and [Tc(NCS)6]2- with E1/2 of 0.18 V vs. SCE. Additional chemical redox reactions of these ions are reported.
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.
Functionalized carborane complexes of the [M(CO)2(NO)] 2+ core (M = 99mTc, Re): A new class of organometallic probes for correlated in vitro and in vivo imaging
Armstrong, Andrea F.,Lebert, Julie M.,Brennan, John D.,Valliant, John F.
, p. 2986 - 2992 (2009/10/23)
Functionalized carborane complexes of the [M(CO)2NO) 2+ (M = Re, 99mTc) core have potential utility as matched pairs of probes for correlated optical (M = Re) and scintigraphic (M = 99mTc) imaging. A synthetic r
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.
