A Coordination Chemistry Study of Solvated Thorium(IV) Ions in Two Oxygen‐Donor Solvents

Abstract

The structures of the dimethyl sulfoxide (dmso) and N,N′‐dimethylpropyleneurea (dmpu) solvated thorium(IV) ions have been studied in solution by extended X‐ray absorption fine structure (EXAFS), and the structure of the solid oxonium bis[nonakis(κO‐dimethyl sulfoxide)]thorium(IV) trifluoromethanesulfonate dihydrate, (H3O)[Th((CH3)2SO)9]2(CF3SO3)9·2H2O (1) has been determined by single‐crystal X‐ray diffraction and EXAFS. Compound 1 was crystallized by evaporating a saturated dmso solution. It consists of two individual nonakis(κO‐dimethyl sulfoxide)thorium(IV) units, both of which have a tricapped trigonal prismatic configuration, as also found in nonakis(dimethyl sulfoxide)thorium(IV) perchlorate previously reported. Mean Th–O bond lengths of 2.47 and 2.43 Å are found for the two structural units, respectively, for which the differences may be explained by differences in occupancy and temperature factors. The EXAFS data of 1 revealed mean Th–O and S–O bond lengths of 2.449(3) and 1.525(3) Å, respectively, and a Th–O–S bond angle of 135.2(5)° to give a Th···S distance of 3.665(7) Å. In dmso solution, the mean Th–O and S–O bond lengths are 2.447(3) and 1.534(3) Å, respectively, the Th–O–S bond angle is 133.5(5)°, and there is a Th···S distance of 3.672(7) Å. The Th–O bond‐length distribution is somewhat asymmetric in both samples with Rmax values of 2.424 and 2.422 Å for 1 and solution, respectively. In dmpu solution, the Th–O and C–O bond lengths are 2.404(5) and 1.264(2) Å, respectively, and there is a Th–O–C angle of 157.1(5)° to give a Th···C distance of 3.594(7) Å. The observed Th–O bond length indicates strongly that thorium(IV) is eight‐coordinate in dmpu.

On the relationship between the structural and volumetric properties of solvated metal ions inO-donor solvents using new structural data in amide solvents

“…2.45 Å, but the coordination numbers are 6, 8, 9 and 9, respectively, 63 – 66 and for the dmso-solvated sodium, calcium and europium( iii ) and thorium( iv ) ions with bond distances of 2.43, 2.36, 2.40 and 2.47 Å, the coordination numbers are 6, 7, 8 and 9, respectively. 31 , 63 , 67 , 68 …”

Metal Complexes Containing Natural and Artificial Radioactive Elements and Their Applications

“…Organic ligands are obviously represented by a major number of examples. Thus, the structure of the dimethyl sulfoxide (DMSO)-solvated thorium(IV) ions was studied in solution by EXAFS) and the structure of the solid oxonium bis [nonakis(κ O -dimethyl sulfoxide)]thorium(IV) trifluoromethane-sulfonate dihydrate, (H 3 O)[Th((CH 3 ) 2 SO) 9 ] 2 (CF 3 SO 3 ) 9 ·2H 2 O was determined [17]. It consists of two individual nonakis(κ- O -dimethyl sulfoxide)thorium(IV) units, both of which have a tricapped trigonal prismatic configuration, as also found earlier in nonakis(dimethyl sulfoxide)thorium(IV) perchlorate.…”

Structure, Stability, and Electronic Properties of Dimethyl Sulfoxide and Dimethyl Formammide Clusters Containing Th4+

“…49 We should note that in the case of La 3+ , the information on structure and coordination numbers obtained from the cluster growing approach were very similar to what was then obtained in liquid phase and they turned out to be crucial in developing a general force field for molecular dynamics studies. The appropriateness of the cluster model approach is further assessed by the fact that in this kind of systems, as observed by Persson and co-workers, the crystal and liquid EXAFS signals are very similar; 34,47 this means that the main features of the metal−DMSO complexation are not modified by a change of bulk phase thus suggesting that the intrinsic ion−solvent interaction is strong enough to determine the solvation structure. This is the main reason why studying clusters in the gas phase allows us in these cases to obtain a realistic picture of the solvation of these ions even if the liquid environmental effect is neglected.…”

“…30 We have focused our attention on Th 4+ solvation because it represents a good model to understand solvation of light bare actinoid cations in oxygen donor solvents. This choice was additionally motivated by the fact that information on coordination of Th 4+ in two oxygen donor solvents (dimethyl sulfoxide (DMSO) and dimethylpropylurea (DMPU)) have been recently determined experimentally in liquid phase by Torapava et al 34 For DMSO, the same authors 34 also reported X-ray structures and extended X-ray absorption fine structure (EXAFS) in solid state. Recently, we have shown that the use of an approach based on the study of small clusters of solvent molecules is extremely useful and we have used it to gather information on the DMSO structure around La 3+ .…”

“…Whereas for hydration of actinoids a relatively high number of experimental and theoretical studies have been reported in the literature addressing the structural properties of solvent molecules around the actinoid bare ions, − much less is known for other oxygen donors organic solvents . Some studies are present for uranyl in liquid DMSO , and some other oxygen donor solvents , whereas for bare ions only few crystal structures are available − (except the aforementioned work of Torapava et al) on Th 4+ .…”