Technetium

Alberto, Roger

doi:10.1016/b0-08-043748-6/04022-6

Cited by 47 publications

(40 citation statements)

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“…[15] The Tc=O distance of 1.641(4) Å is within the expected range for a technetium-oxygen double bond. [16] www.eurjic.org Figure 1. Ellipsoid representation of the molecular structure of 3.…”

Section: Resultsmentioning

confidence: 98%

Mixed‐Ligand Complexes of Technetium and Rhenium with Tridentate Benzamidines and Bidentate Benzoylthioureas

2009

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Mixed‐ligand complexes of technetium(V) or rhenium(V) containing tridentate N‐[(dialkylamino)(thiocarbonyl)]benzamidine (H2L1) and bidentate N,N‐dialkyl‐N′‐benzoylthiourea (HL2) ligands were formed in high yields when (NBu4)[MOCl4] (M = Tc or Re) or [ReOCl3(PPh3)2] was treated with mixtures of the proligands. Other approaches for the synthesis of the products are reactions of [MOCl(L1)] complexes with HL2 or compounds of the composition [ReOCl2(PPh3)(L2)] with H2L1. The resulting air‐stable [MO(L1)(L2)] complexes possess potential for the development of metal‐based radiopharmaceuticals. [TcO(L1)(L2)] complexes are readily reduced by PPh3 with formation of [Tc(L1)(L2)(PPh3)]. The resulting TcIII complexes undergo two almost‐reversible oxidation steps corresponding to one‐electron transfer processes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Resultsmentioning

confidence: 98%

Mixed‐Ligand Complexes of Technetium and Rhenium with Tridentate Benzamidines and Bidentate Benzoylthioureas

2009

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“…The desalted product was then eluted with MeOH, the solvent evaporated, and the product dried under high vacuum. IR Spectra: n Ä in cm (10). To a soln.…”

Section: Experimental Partmentioning

confidence: 99%

S‐Functionalized Cysteine: Powerful Ligands for the Labelling of Bioactive Molecules with Triaquatricarbonyltechnetium‐99m(1+) ([^99mTc(OH₂)₃(CO)₃]⁺)

Staveren

Benny

Waibel

et al. 2005

Helvetica Chimica Acta

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S‐Alkylated cysteines are used as efficient tridentate N,O,S‐donor‐atom ligands for the fac‐[M(CO)3]+ moiety (M=99mTc or Re). Reaction of (Et4N)2[ReBr3(CO)3] (3) with the model S‐benzyl‐L‐cysteine (2) leads to the formation of [Re(2′)(CO)3] (4) as the exclusive product (2′=C‐terminal anion of 2). The tridentate nature of the alkylated cysteine in 4 was established by X‐ray crystallography. Compound 2 reacts with [99mTc(OH2)3(CO)3]+ under mild conditions (10−4 M, 50°, 30 min) to afford [99mTc(2′)(CO)3] (5) and represents, therefore, an efficient chelator for the labelling of biomolecules. L‐Cysteine, S‐alkylated with a 3‐aminopropyl group (→7), was conjugated via a peptide coupling sequence with Coα‐[α‐(5,6‐dimethyl‐1H‐benzimidazolyl)]‐Coβ‐cyanocobamic b‐acid (6), the b‐acid of cyanocob(III)alamin (vitamin B12) (Scheme 3). More convenient was a one‐pot procedure with a derivative of vitamin B12 comprising a free amine group at the b‐position. This amine 15 was treated with NHS (N‐hydroxysuccinimide)‐activated 1‐iodoacetic acid 14 to introduce an I‐substituent in vitamin B12. Subsequent addition of unprotected L‐cysteine resulted in nucleophilic displacement of the I‐atom by the S‐substituent, affording the vitamin B12 alkylated cysteine fragment 17 (Scheme 4). The procedure was quantitative and did not require purification of intermediates. Both cobalamin–cysteine conjugates could be efficiently labelled with [99mTc(OH2)3(CO)3]+ (1) under conditions identical to those of the model complex 5. Biodistribution studies of the cobalamin conjugates in mice bearing B10‐F16 melanoma tumors showed a tumor uptake of 8.1±0.6% and 4.4±0.5% injected dose per gram of tumor tissue after 4 h and 24 h, respectively (Table 1).

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“…[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.…”

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confidence: 99%

“…[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.…”

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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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Technetium

Cited by 47 publications

References 602 publications

Mixed‐Ligand Complexes of Technetium and Rhenium with Tridentate Benzamidines and Bidentate Benzoylthioureas

Mixed‐Ligand Complexes of Technetium and Rhenium with Tridentate Benzamidines and Bidentate Benzoylthioureas

S‐Functionalized Cysteine: Powerful Ligands for the Labelling of Bioactive Molecules with Triaquatricarbonyltechnetium‐99m(1+) ([^99mTc(OH₂)₃(CO)₃]⁺)

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

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Technetium

Cited by 47 publications

References 602 publications

Mixed‐Ligand Complexes of Technetium and Rhenium with Tridentate Benzamidines and Bidentate Benzoylthioureas

Mixed‐Ligand Complexes of Technetium and Rhenium with Tridentate Benzamidines and Bidentate Benzoylthioureas

S‐Functionalized Cysteine: Powerful Ligands for the Labelling of Bioactive Molecules with Triaquatricarbonyltechnetium‐99m(1+) ([99mTc(OH2)3(CO)3]+)

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

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S‐Functionalized Cysteine: Powerful Ligands for the Labelling of Bioactive Molecules with Triaquatricarbonyltechnetium‐99m(1+) ([^99mTc(OH₂)₃(CO)₃]⁺)