Synthetic and Coordination Chemistry of the Heavier Trivalent Technetium Binary Halides: Uncovering Technetium Triiodide

Johnstone, Erik V.; Poineau, Frédéric; Starkey, Jenna; Hartmann, Thomas; Forster, Paul M.; Ma, Liang; Hilgar, Jeremy D.; Rodriguez, Efrain E.; Farmand, Romina; Czerwinski, Kenneth R.; Sattelberger, Alfred P.

doi:10.1021/ic402278c

Cited by 5 publications

(7 citation statements)

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“…Technetium tribromide can be obtained by the reaction of Tc metal and Br 2 (Tc/Br ratio, ∼1:3) in a sealed tube at 400 °C or via the reaction between Tc 2 (O 2 CCH 3 ) 4 Cl 2 and flowing HBr gas at 300 °C. , Technetium tribromide obtained from the reaction of Tc 2 (O 2 CCH 3 ) 4 Cl 2 and HBr(g) has the same structure (TiI 3 structure-type) as the material obtained by direct combination of the elements. It was hoped that the reaction between Tc 2 (O 2 CCH 3 ) 4 Cl 2 and HBr(g) would mimic the rhenium system and provide Tc 3 Br 9 …”

Section: Technetium Bromidesmentioning

confidence: 99%

“…Technetium triiodide has been obtained by two methods: the reaction between Tc 2 (O 2 CCH 3 ) 4 Cl 2 and flowing HI gas and the reaction between the elements in sealed tubes. 45 Concerning the first method, technetium triiodide was obtained from the reaction of Tc 2 (O 2 CCH 3 ) 4 Cl 2 with HI at 150 and 300 °C. In the second method, the reaction of Tc metal and I 2 (Tc/I ratio, 1:3) was investigated in sealed tubes at 250 and 400 °C.…”

Section: Technetium Iodidesmentioning

confidence: 99%

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Recent Advances in Technetium Halide Chemistry

et al. 2014

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Transition metal binary halides are fundamental compounds, and the study of their structure, bonding, and other properties gives chemists a better understanding of physicochemical trends across the periodic table. One transition metal whose halide chemistry is underdeveloped is technetium, the lightest radioelement. For half a century, the halide chemistry of technetium has been defined by three compounds: TcF6, TcF5, and TcCl4. The absence of Tc binary bromides and iodides in the literature was surprising considering the existence of such compounds for all of the elements surrounding technetium. The common synthetic routes that scientists use to obtain binary halides of the neighboring elements, such as sealed tube reactions between elements and flowing gas reactions between a molecular complex and HX gas (X = Cl, Br, or I), had not been reported for technetium. In this Account, we discuss how we used these routes to revisit the halide chemistry of technetium. We report seven new phases: TcBr4, TcBr3, α/β-TcCl3, α/β-TcCl2, and TcI3. Technetium tetrachloride and tetrabromide are isostructural to PtX4 (X = Cl or Br) and consist of infinite chains of edge-sharing TcX6 octahedra. Trivalent technetium halides are isostructural to ruthenium and molybdenum (β-TcCl3, TcBr3, and TcI3) and to rhenium (α-TcCl3). Technetium tribromide and triiodide exhibit the TiI3 structure-type and consist of infinite chains of face-sharing TcX6 (X = Br or I) octahedra. Concerning the trichlorides, β-TcCl3 crystallizes with the AlCl3 structure-type and consists of infinite layers of edge-sharing TcCl6 octahedra, while α-TcCl3 consists of infinite layers of Tc3Cl9 units. Both phases of technetium dichloride exhibit new structure-types that consist of infinite chains of [Tc2Cl8] units. For the technetium binary halides, we studied the metal-metal interaction by theoretical methods and magnetic measurements. The change of the electronic configuration of the metal atom from d(3) (Tc(IV)) to d(5) (Tc(II)) is accompanied by the formation of metal-metal bonds in the coordination polyhedra. There is no metal-metal interaction in TcX4, a Tc═Tc double bond is present in α/β-TcCl3, and a Tc≡Tc triple bond is present in α/β-TcCl2. We investigated the thermal behavior of these binary halides in sealed tubes under vacuum at elevated temperature. Technetium tetrachloride decomposes stepwise to α-TcCl3 and β-TcCl2 at 450 °C, while β-TcCl3 converts to α-TcCl3 at 280 °C. The technetium dichlorides disproportionate to Tc metal and TcCl4 above ∼600 °C. At 450 °C in a sealed Pyrex tube, TcBr3 decomposes to Na{[Tc6Br12]2Br}, while TcI3 decomposes to Tc metal. We have used technetium tribromide in the preparation of new divalent complexes; we expect that the other halides will also serve as starting materials for the synthesis of new compounds (e.g., complexes with a Tc3(9+) core, divalent iodide complexes, binary carbides, nitrides, and phosphides, etc.). Technetium halides may also find applications in the nuclear fuel cycle; their thermal properties could be...

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Section: Technetium Bromidesmentioning

confidence: 99%

Section: Technetium Iodidesmentioning

confidence: 99%

Recent Advances in Technetium Halide Chemistry

et al. 2014

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“…Still, many compound classes were not studied, and it was not until the 21st century that, e.g., binary halides of the middle and lower oxidations states were prepared and comprehensively characterized ( vide supra ). − They are essential for completing knowledge of the manganese triad and for systematizing vertical, horizontal, and diagonal trends but even more for acting as starting materials for extended, synthetic coordination and organometallic chemistry.…”

Section: Introductionmentioning

confidence: 99%

Role of Pure Technetium Chemistry: Are There Still Links to Applications in Imaging?

Alberto

2023

Inorg. Chem.

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The discovery and development of new 99m Tc-based radiopharmaceuticals or labeled drugs in general is based on innovative, pure chemistry and subsequent, application-targeted research. This was the case for all currently clinically applied imaging agents. Most of them were market-introduced some 20 years ago, and the few more recent ones are based on even older chemistry, albeit technetium chemistry has made substantial progress over the last 20 years. This progress though is not mirrored by new molecular imaging agents and is even accompanied by a steady decrease in the number of groups active in pure and applied technetium chemistry, a contrast to the trends in most other fields in which d-elements play a central role. The decrease in research with technetium has been partly counterbalanced by a strong increase of research activities with homologous, cold rhenium compounds for therapy, disclosing in the future eventually a quite unique opportunity for theranostics. This Viewpoint analyzes the pathways that led to radiopharmaceuticals in the past and their underlying fundamental contributions. It attempts to tackle the question of why new chemistry still does not lead to new imaging agents, i.e., the question of whether pure technetium chemistry is still needed at all.

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“…[3] As part of an effort to expand our knowledge of technetium metal-metal bond chemistry, we prepared seven new binary halides (TcBr 4 , TcBr 3 , -TcCl 3 , -TcCl 2, and TcI 3 ). [4][5][6][7][8][9][10] The oxidation state of the Tc atom likely determines the extent to which Tc-Tc bonding occurs. In the tetrahalide TcBr 4 , there is no discernable metal-metal interaction.…”

Section: Introductionmentioning

confidence: 99%

“…Technetium trihalides (TcBr 3 , TcI 3 and -TcCl 3 ) have been obtained from the reaction of Tc 2 (O 2 CCH 3 ) 4 Cl 2 with HX gas at 300 ºC. [7,8] Thus, new technetium metal-metal bonded dimers with carboxylate ligands are of particular interest as precursors for the preparation of new technetium binary halides, TcX y (X = F, Cl, Br, I; y = 2, 3, 4). [9,10] The study of Tc 2 (O 2 CCH 3 ) 2 Cl 4 also permitted to better understand the influence of acetate ligand on the Tc-Tc bonding.…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal synthesis and solid-state structures of polynuclear technetium iodide compounds

Kerlin

Poineau

Forster

et al. 2015

Inorganica Chimica Acta

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Two new technetium iodide compounds, Tc 2 (O 2 CCH 3 ) 4 I and K[Tc 8 (μ-I) 8 I 4 ]I, were synthesized in an autoclave from the reaction of KTcO 4 in glacial acetic acid with hydroiodic acid and/or alkali metal iodide salts at 210 ºC under 60-70 atm hydrogen pressure. The structures of Tc 2 (O 2 CCH 3 ) 4 I and K[Tc 8 (μ-I) 8 I 4 ]I were solved by single-crystal X-ray diffraction. The compound Tc 2 (O 2 CCH 3 ) 4 I crystallizes in the monoclinic space group C2/m with a = 7.1194(6) Å, b = 14.5851(13) Å, c = 7.1586(6) Å, and β = 110.9540(10)º. The structure of Tc 2 (O 2 CCH 3 ) 4 I consists of infinite chains of Tc 2 (O 2 CCH 3 ) 4 + units linked by bridging iodides, an arrangement similar to the one found in Tc 2 (O 2 CCH 3 ) 4 X (X = Cl, Br). The Tc-Tc separation in Tc 2 (O 2 CCH 3 ) 4 I (i.e., 2.1146(4) Å) is consistent with the presence of a Tc-Tc bond of order 3.5. Magnetic susceptibility measurements reveal Tc 2 (O 2 CCH 3 ) 4 I to be paramagnetic (μ eff = 1.84 B.M.) and support the electronic configuration        1 for the Tc 2 5+ unit in the compound. The compound K[Tc 8 (μ-I) 8 I 4 ]I crystallizes in the monoclinic space group P2 1 /n with a = 8.0018(5) Å, b = 14.5125(10) Å, c = 13.1948(9) Å, and β = 102.3090(10)º, and is the first octanuclear technetium iodide cluster to be reported. The Tc-Tc separations in the [Tc 8 (μ-I) 8 I 4 ] cluster (i.e., 2.164(3) Å, 2.5308(8) Å and 2.72(3) Å) suggest the presence of Tc≡Tc triple bonds, Tc=Tc double bonds and Tc-Tc single bonds.

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Synthetic and Coordination Chemistry of the Heavier Trivalent Technetium Binary Halides: Uncovering Technetium Triiodide

Cited by 5 publications

References 48 publications

Recent Advances in Technetium Halide Chemistry

Recent Advances in Technetium Halide Chemistry

Role of Pure Technetium Chemistry: Are There Still Links to Applications in Imaging?

Hydrothermal synthesis and solid-state structures of polynuclear technetium iodide compounds

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