Structural (EXAFS) and solution equilibrium studies on the oxotechnetium(V) complexes TcOX4- and TcOX52- (X = Cl, Br)

Thomas, Rudy; Heeg, Mary Jane; Elder, R. C.; Deutsch, Edward

doi:10.1021/ic00204a014

Cited by 39 publications

(17 citation statements)

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“…The two species observed here are most likely to be [TcOC15] 2-and TcOC14 and their presence demonstrates the existente of an equilibrium between tetrachloro-and pentachloro-oxotechnetate species. This would be con- sistent with the Raman spectroscopic and EXAFS results of Thomas et al [26], bearing in mind that H:O is most likely to be associated with H2SO 4 in these solutions, rather than with the Te anion complex.…”

Section: Epr Of [Tc(v1)o] 4+ Complexessupporting

confidence: 79%

EPR studies of technetium complexes in frozen solution

Baldas¹,

Boas²,

Williams³

1996

Appl. Magn. Reson.

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Section: Epr Of [Tc(v1)o] 4+ Complexessupporting

confidence: 79%

EPR studies of technetium complexes in frozen solution

Baldas¹,

Boas²,

Williams³

1996

Appl. Magn. Reson.

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“…A band at 400 cm −1 may be attributed to the Tc−O(H 2 O) stretch. There is no Tc(IV)=O band after 960 cm −1 considering the Tc(V)=O band observed at 965 and 1011 cm −1 in the Raman spectrum of TcOCl5 2− and TcOCl 4 − , respectively[13].…”

mentioning

confidence: 89%

“…The empirical fitting procedure is used in the analysis of the spectra of TcCl 6 2− and TcO 4 − with four free parameters: N, r, ∆σ and ∆E 0 (E 0 , energy at which k = 0). The model spectra which have provided amplitude and phase data for Tc−O and Tc−Cl scattering are NH 4 TcO 4 (or TcO 2 ) and K 2 TcCl 6 [13][14][15]. All fits are based on a k 2 weighting factor.…”

Section: Exafsmentioning

confidence: 99%

The speciation of Tc(IV) in chloride solutions

Said¹,

Fattahi²,

Musikas³

et al. 2000

Radiochimica Acta

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Technetium / Pertechnetate / Speciation / ChlorideSummary. The speciation of tetravalent technetium has been studied in HCl solutions ranging from 1.0 to 6.0 M. Tc(IV) exists in 6.0 M HCl as the well characterized TcCl 6 2− chloride complex. In 1.0 M HCl, the chloride ligands of TcCl 6 2− are slowly substituted by other ligands such as H(4−m−2n− p)+ compounds may form with (m + n + p + q) = 6. Several speciation techniques such as UV-visible and Raman spectrometries, X-ray absorption spectroscopy and electrochemistry have enabled to get an insight into this problem. All the results have indicated two most likely species of Tc(IV) after aging for about ten days in 1.0 M HCl to be aquo-chlorocomplexes of technetium and not oxo-chorocomplexes: TcCl 5 · H 2 O − and TcCl 4 · 2H 2 O.

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“…[6] In concentrated acid, permetallates are generally unstable and reduction, dimerisation, dehydration or complexation can occur. [7,8,9,10] The reaction of pertechnetate in water with strong acid leads to dehydration and various complexes with TcO 3 + core have been synthesized. [11] In theses synthetic reactions, it is assumed that the anhydrous Tc 2 O 7 is formed as an intermediate product.…”

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confidence: 99%

Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies

et al. 2010

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Summary. The speciation of Tc(VII) in 12 M sulfuric acid was studied by NMR, UVvisible and XAFS spectroscopy, experimental results were supported by DFT calculation and were in agreement with the formation of TcO 3 OH(H 2 O) 2 .Heptavalent transition metal complexes of group VII with the d 0 electronic configuration are often used in catalysis and biomedical applications. [1,2,3] For manganese, the high electron affinity and oxidation potential of its heptavalent complexes make these species the catalysts of choice for oxidation of organic compounds.[4] The chemistry of Re(VII) complexes has been extensively studied, and species with the ReO 3 + core (e.g., CH 3 ReO 3 ) have been reported to be efficient catalysts. [3] Concerning technetium, its coordination chemistry has mainly been driven by radiopharmaceutical applications. Pentavalent and trivalent Tc complexes have been the most studied while heptavalent coordination complexes are still rare. [5] Permetallates with the tetrahedral geometry are the most common heptavalent species and are stable in aqueous media over a large range of pH and electrochemical potential. [6] In concentrated acid, permetallates are generally unstable and reduction, dimerisation, dehydration or complexation can occur. [7,8,9,10] The reaction of pertechnetate in water with strong acid leads to dehydration and various complexes with TcO 3 + core have been synthesized. [11] In theses synthetic reactions, it is assumed that the anhydrous Tc 2 O 7 is formed as an intermediate product. [11] Sulfuric acid is widely used in industrial applications; it is also a solvent of choice for dehydration process. [12-13] Speciation of Mn(VII) in H 2 SO 4 has been documented; manganese heptoxide is formed after dissolution of KMnO 4 and the MnO 3 + cation has been reported. [14,15,16]. For technetium and rhenium, speciation data are still sparse, the HReO 2 (SO 4 ) 2 .3H 2 O complex has been mentioned while technetium heptoxide has been proposed but no structural nor speciation data were provided. [17][18] In the present work, the speciation of technetium complexes after dissolution of KTcO 4 in sulfuric acid has been performed. The molecular structure and spectroscopic properties of the complexes were studied by UV-visible, X-ray absorption fine structure (XAFS) and NMR spectroscopy and density functional theory (DFT) techniques.Potassium pertechnetate (~ 30 mg) was placed in glass vials, and 1 M, 6 M, 12 M sulfuric acid (5 mL) was added with a glass pipette. After dissolution of the salt, a yellow color is observed in 12 M while for 1 M and 6 M, the solution remains clear. UV-visible spectroscopy measurements in 1 M and 6 M show the presence of TcO 4 -while in 12 M, the spectrum of the yellow solution differs from that of the pertechenate (vide supra). The conditions of formation of the yellow species were investigated by NMR spectroscopy. Technetium samples were prepared in H 2 SO 4 (from 3 M to 18 M) and 99 The 99 Tc NMR data were fit by allowing the pK a s and the chemical shifts of the unprot...

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Structural (EXAFS) and solution equilibrium studies on the oxotechnetium(V) complexes TcOX4- and TcOX52- (X = Cl, Br)

Cited by 39 publications

References 3 publications

EPR studies of technetium complexes in frozen solution

EPR studies of technetium complexes in frozen solution

The speciation of Tc(IV) in chloride solutions

Speciation of heptavalent technetium in sulfuric acid: structural and spectroscopic studies

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