Thorium(IV) and Uranium(IV) Complexes with 2,6-Dipicolinoylbis(<i>N</i>,<i>N</i>-diethylthiourea) Ligands

The reaction of thorium nitrate hydrate with 2,6-dipicolinoylbis(<i>N</i>,<i>N</i>-diethylthiourea), H<sub>2</sub>L<sup>pic</sup>, results in the hydrolysis of the organic ligand and the formation of [Th(2,6-dipicolinolate)<sub>2</sub>(H<...

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Bibliographic Details
Main Authors: Christelle Njiki Noufele, Juliane März, Ulrich Abram
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Molbank
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Online Access:https://www.mdpi.com/1422-8599/2025/1/M1957
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Summary:The reaction of thorium nitrate hydrate with 2,6-dipicolinoylbis(<i>N</i>,<i>N</i>-diethylthiourea), H<sub>2</sub>L<sup>pic</sup>, results in the hydrolysis of the organic ligand and the formation of [Th(2,6-dipicolinolate)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>] (<b>1</b>). Hydrolysis can be avoided by the use of [ThCl<sub>4</sub>(DME)<sub>2</sub>] (DME = 1,2-dimethoxyethane) as the starting material and the exclusion of water. The product, [Th(L<sup>pic</sup>)<sub>3</sub>]<sup>2−</sup> (<b>2</b>), crystallizes as diammonium salt in form of yellow crystals in moderate yields. The thorium ion in the complex is nine-coordinate by the central <i>O</i>,<i>N</i>,<i>O</i> donor atoms of three deprotonated {L<sup>pic</sup>}<sup>2−</sup> ligands. The sulfur atoms of the ligands do not bind to the actinide ion, but establish hydrogen bonds to the ammonium counter ions. A similar coordination sphere is also observed in the uranium(IV) complex [UAu<sub>2</sub>(L<sup>pic</sup>)<sub>3</sub>}] (<b>3</b>), which was obtained from a reaction between H<sub>2</sub>L<sup>pic</sup>, [U<sub>2</sub>I<sub>6</sub>(1,4-dioxane)<sub>3</sub>] and [AuCl(tht)] (tht = tetrahydrothiophene) in the presence of triethylamine. Charge compensation is established by the linear coordination of two Au<sup>+</sup> ions between each two sulfur atoms of the ligands. The products have been studied by X-ray diffraction and IR spectroscopy. The actinide ions in both {L<sup>pic</sup>}<sup>2−</sup> complexes have coordination number nine, but establish slightly different coordination spheres.
ISSN:1422-8599