A 70-Year-Old Mystery in Technetium Chemistry Explained by the New Technetium Polyoxometalate [H7O3]4[Tc20O68] ⋅ 4H2O

Authors

Konstantin E. German, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences
Alexander M. Fedoseev, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences
Mikhail S. Grigoriev, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences
Gayane A. Kirakosyan, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences
Thomas Dumas, Université de Montpellier
Christophe Den Auwer, Université Côte d'Azur
Philippe Moisy, Université de Montpellier
Keith V. Lawler, University of Nevada, Las Vegas
Paul M. Forster, University of Nevada, Las VegasFollow
Frederic Poineau, University of Nevada, Las VegasFollow

Document Type

Article

Publication Date

7-9-2021

Publication Title

Chemistry - A European Journal

First page number:

1

Last page number:

9

Abstract

[H7O3]4[Tc20O68] ⋅ 4H2O [1] was prepared from an aqueous Tc2O7 solution concentrated over anhydrous H2SO4. [Tc20O68]4− is the first polyanionic species to be reported for Tc. The unit cell contains one centrosymmetric [Tc20O68]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 Tc4O4 ring. The four Tc(V)O6 octahedra are decorated by sixteen Tc(VII)O4 tetrahedra. Calculations show the bonding within the Tc4O4 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.

Keywords

Electronic structures; Isopolyanion; Technetium; X-ray diffraction; XAFS

Disciplines

Chemistry | Physical Sciences and Mathematics

Language

English

Repository Citation

German, K. E., Fedoseev, A. M., Grigoriev, M. S., Kirakosyan, G. A., Dumas, T., Den Auwer, C., Moisy, P., Lawler, K. V., Forster, P. M., Poineau, F. (2021). A 70-Year-Old Mystery in Technetium Chemistry Explained by the New Technetium Polyoxometalate [H7O3]4[Tc20O68] ⋅ 4H2O. Chemistry - A European Journal 1-9.
http://dx.doi.org/10.1002/chem.202102035