Thiourea as a Stabilizer of Reduced Forms of Technetium─Tc(III) and Tc(IV): Experimental and Theoretical Studies of Complexes

Mikhail A Volkov; Anton P Novikov; Mikhail S Grigoriev; Yuri M Nevolin; Konstantin E German

doi:10.1021/acs.inorgchem.2c03258

Thiourea as a Stabilizer of Reduced Forms of Technetium─Tc(III) and Tc(IV): Experimental and Theoretical Studies of Complexes

Inorg Chem. 2023 Jan 9;62(1):256-265. doi: 10.1021/acs.inorgchem.2c03258. Epub 2022 Dec 16.

Authors

Mikhail A Volkov¹, Anton P Novikov¹, Mikhail S Grigoriev¹, Yuri M Nevolin¹, Konstantin E German¹

Affiliation

¹ Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, Leninsky prospect 31, bldg 4, Moscow119071, Russia.

PMID: 36525584
DOI: 10.1021/acs.inorgchem.2c03258

Abstract

This paper presents synthetic methods for the preparation of Tc(III) and Tc(IV) coordination compounds with thiourea. We have shown that the main product of the synthesis is the complex [TcTu₅X]X₂, (Tu = (NH₂)₂CS, X = Cl, Br) and not [TcTu₆]Cl₃·4H₂O, as previously thought. Tu₂[TcX₆]X₂·3H₂O is the main technetium-containing byproduct of the reaction. All reaction products, including byproducts, were characterized by X-ray diffraction analysis. We also measured the solubility for the obtained Tc(III) complexes. This research work considers the process of thermolysis of the obtained Tc(III) complexes and shows that the presence of sulfur atoms in the coordination sphere can inhibit the process of metal formation in an argon-hydrogen medium. The analysis of nonvalent interactions in Tc(III) complexes showed that the main contribution is made by van der Waals interactions of the H···H type (40.8-42.3%) and hydrogen bonds Hal···H/H···Hal and H···S/S···H, which are 41.6-44.5% in total. As the temperature decreases, the proportion of H···H contacts and H bonds decreases, and when the halogen (Cl by Br) is replaced, the proportion of H bonds increases and the proportion of van der Waals interactions decreases.