A 70‐Year‐Old Mystery in Technetium Chemistry Explained by the New Technetium Polyoxometalate [H 7 O 3 ] 4 [Tc 20 O 68 ] ⋅ 4H 2 O

Autor: Thomas Dumas, Mikhail S. Grigoriev, Frederic Poineau, Konstantin E. German, Paul M. Forster, Alexander M. Fedoseev, Christophe Den Auwer, Keith V. Lawler, G. A. Kirakosyan, Philippe Moisy
Rok vydání: 2021
Předmět:
Zdroj: Chemistry – A European Journal. 27:13624-13631
ISSN: 1521-3765
0947-6539
Popis: [H7 O3 ]4 [Tc20 O68 ] ⋅ 4H2 O [1] was prepared from an aqueous Tc2 O7 solution concentrated over anhydrous H2 SO4 . [Tc20 O68 ]4- is the first polyanionic species to be reported for Tc. The unit cell contains one centrosymmetric [Tc20 O68 ]4- polyanion as well as hydronium ions and water molecules. The core of the structure consists of four Tc(V)O6 octahedra that form a square Tc4 O4 ring. The four Tc(V)O6 octahedra are decorated by sixteen Tc(VII)O4 tetrahedra. Calculations show the bonding within the Tc4 O4 ring to consist of a 3-center bond formed between each neighboring pair of Tc atoms and their bridging oxygen. Calculations also indicate that a strong d→d electronic transition at 513 nm is the origin of the red color of [1]. The characterization of red HTcO4 solutions by X-ray absorption spectroscopy has complemented the description of this compound in aqueous solution. The formation mechanisms in solution, including the possible role of technetium's radioactivity in the formation of [1], are discussed.
Databáze: OpenAIRE
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