Hydration of the Yttrium(III) Ion in Aqueous Solution. An X-ray Diffraction and XAFS Structural Study

Abstract

The yttrium(III) ion is found by means of extended X-ray absorption fine-structure spectroscopy (EXAFS) and large angle X-ray scattering (LAXS) to be hydrated by eight water molecules in aqueous solution. The EXAFS data show a slightly asymmetric distribution of the Y−O bond distances with the centroid of the distribution at 2.368(5) Å. The width of the distribution implies a positional disorder of about 0.1 Å on top of the thermally induced variation in the Y−O bond distances. The aqueous solutions and the solid compound [Y(OH2)8]Cl3·(15-crown-5), in which eight water oxygen atoms form a distorted bicapped trigonal prism around the hydrated yttrium(III) ion, show very similar near-edge and EXAFS spectra. For aqueous solutions the LAXS data give a mean Y−O bond distance of 2.365(5) Å and show the presence of a second hydration sphere consisting of approximately 16 oxygen atoms at a mean Y···O distance of 4.40(4) Å.

Interplay of computer simulations and x-ray absorption spectra in the study of the bromide hydration structure

“…49 Due to the characteristics of the probability distribution function, distances obtained by a conventional fit procedure to the EXAFS spectrum are observed to be close to the maximum of the radial distribution function when solely DW factors are considered, FIG. 6.…”

Highly Hydrated Cations: Deficiency, Mobility, and Coordination of Water in Crystalline Nonahydrated Scandium(III), Yttrium(III), and Lanthanoid(III) Trifluoromethanesulfonates

“…This is probably the main reason why the relatively small scandium(iii) ion can obtain the high hydration number of about eight in the hydrated scandium(iii) trifluoromethanesulfonate, while the hydration number is only seven in the halides with weaker hydrogen bonds [32] and six for the hydrated methanesulfonate [Sc-(H 2 O) 6 ][Sc(CH 3 SO 3 ) 6 ] with strong hydrogen bonding but in a different arrangement. [19] Also, the efficiency especially of scandium(iii) trifluoromethanesulfonate as a water-tolerant Lewis acid catalyst for many organic syntheses [12,13] is possibly connected to the potential for the donor atoms of the substrate molecules to bind to the metal ion in the capping positions of a trigonal prism. The number of water molecules per metal ion was determined by several methods.…”

“…[30] The hydration number for the yttrium(iii) ion in aqueous solution could be determined by comparing X-ray absorption spectra with those from carefully chosen solid hydrates, supported by results from X-ray diffraction studies on solutions. [19] A similar study of the hydrated scandium(iii) ion in solution is less straightforward, since only a few well-determined crystal structures are known of suitable solid hydrates [13,31,32] and the low atomic number causes experimental difficulties. The effective ionic radii for scandium(iii) in six, seven and eight coordination (0.745, 0.80 and 0.87 , respectively) are derived from scandium(iii) compounds with oxygen-donor ligands.…”

“…[18] The mean M III ÀO distance from crystal structures of the trifluoromethanesulfonate salts of the hydrated d 0 ions of Group 3 (2.55, 2.40 and 2.28 for M = La, Y and Sc, respectively) changes substantially for nine coordination in the TTP configuration. [10,19,20] However, in aqueous solution only the largest ion, lanthanum(iii), coordinates nine water molecules; [21] the yttrium(iii) ion coordinates eight, [19] while the hydration number of the relatively small scandium(iii) ion is probably around seven, [1] with the mean MÀO distances being 2.54-2.58, [21] 2.37 [19] and 2.17-2.18 , [22,23] respectively, in asymmetric radial distributions.…”

Dimethyl sulfoxide solvates of the aluminium(iii), gallium(iii) and indium(iii) ions. A crystallographic, EXAFS and vibrational spectroscopic studyElectronic supplementary information (ESI) available: normalized X-ray absorption edges, calculated separate contributions of the different scattering paths to the EXAFS oscillations for the dimethyl sulfoxide solvated gallium(iii) and indium(iii) ions in the solid state and solution; correlation between compression ratio (s/h) and bond lengths in [M(dmso)6]3+ c

“…Scandium() probably coordinates † Electronic supplementary information (ESI) available: normalized Xray absorption edges, calculated separate contributions of the different scattering paths to the EXAFS oscillations for the dimethyl sulfoxide solvated gallium() and indium() ions in the solid state and solution; correlation between compression ratio (s/h) and bond lengths in [M(dmso) 6 ] 3ϩ complexes; correlation between metal-oxygen (M-O) force constants and bond lengths in [M(dmso) 6 ] 3ϩ complexes. See http:// www.rsc.org/suppdata/dt/b2/b212140a/ seven water molecules in a monocapped trigonal prism, 8 yttrium() eight in a square antiprism, 9 and lanthanum() nine waters in a tricapped trigonal prism. 10 Thus, even though thallium() and indium() have larger ionic radii in sixcoordination than Sc 3ϩ , 0.885, 0.800 and 0.745 Å, 11 respectively, their hydration numbers are smaller.…”