Title

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

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

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