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As a continuation of our previous studies of light lanthanides (La, Ce, Pr, and Nd) with (Pyrazol-1-yl)acetic acid (L), we reacted L with the heavier lanthanides in aqueous solution at pH 5 and synthesized lanthanide complexes of the general formula [Ln(L)3(H2O)2]·H2O (Ln=Eu, 1; Gd, 2; Dy, 3; Ho, 4; Er, 5; Yb, 6; Lu, 7) and [HoL(NO3)2(H2O)3] (8). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Three distinct crystallographic structures are governed by the different coordination modes of the carboxylate groups in L: terminal bidentate, bridging bidentate and tridentate coordination in 1–3, terminal and bridging bidentate coordination in 4–7, and bridging bidentate coordination in 8. The solid state UV–Vis–NIR diffuse reflectance spectra and the solution UV–Vis–NIR absorption spectra differ, suggesting different coordination environments in solution and solid state. The coordination-induced shifts of the 13C NMR signals for [Lu(L)3(H2O)2]·H2O (7) in D2O show that the carboxylate groups of the ligand are coordinated with the Lu(III) ion in solution. [ABSTRACT FROM AUTHOR]

As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-l-yl)acetic add (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-dements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = S and synthesized four lanthanide complexes of general formula [Ln(L)3(H20)2]-nHi0 (l, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = l). All complexes were characterized by single crystal X-ray diffraction analysis revealing one-dimensional chain formations. Two distinct crystallographic structures are governed by the different coordination modes of carboxylate groups in L: terminal bidentate and bridging tridentate (l-- 3); terminal bidentate, bridging bidentate, and tridentate coordination in 4. Comparison of the solid state UV--vis--NIR diffuse reflectance spectra with solution state UV--vis--NIR spectra suggests a different spedes in solution and solid state. The different coordination in solid state and solution was verified by distinctive, 3C NMR signals of the carboxylate groups in the solid state NMR. [ABSTRACT FROM AUTHOR]

Despite the wide range of applications of ɑ-hydroxyisobutyric acid (HIBA) in biochemical processes, pharmaceutical formulations, and group and elemental separations of lanthanides and actinides, the structures and geometries of lanthanide--HIBA complexes are still not well understood. We reacted HIBA with lanthanides in aqueous solution at pH = 5 and synthesized 14 lanthanide--HIBA complexes of the formula [Ln(HIBA)2(H2O)2](NO3)⋅H2O (Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9), Ho (10), Er (11), Tm (12), Yb (13), Lu (14)), isolating single crystals (1-7, 10, and 11) and powders (8, 9, and 12-14). Both single-crystal and powder X-ray diffraction studies reveal a two-dimensional extended structure across the entire lanthanide series. The environment around the eight-coordinated Ln(III) atom is best described as a distorted dodecahedron, where HIBA acts as a monoanionic tridentate ligand with one carboxylato oxygen atom and one hydroxyl oxygen atom chelating to one Ln(III) center. The carboxylato oxygen atom from a second HIBA ligand bridges to a neighboring Ln(III) atom to form a two-dimensional extended structure. While the coordination mode for HIBA is identical across the lanthanide series, three different structure types are found for La, Ce--Ho, and Er--Lu. Solution characterization using 13C NMR further confirmed a single solution complex under the crystallization conditions. Raman and UV--vis--NIR absorbance and diffuse reflectance spectra of HIBA--Ln (III) complexes were also measured. [ABSTRACT FROM AUTHOR]

In alkaline carbonate solutions both technetium and uraniumexistas anionic species, TcO4–and UO2(CO3)34–, which makesseparating Tc and U from each other more challenging compared to acidicPUREX type solutions where uranium forms neutral or cationic complexes.We tested the batch separation of 99Tc, 238U,and 239Pu from carbonate solutions using anion exchangeresins with different properties, including Purolite A530E, ReillexHPQ, and Dowex Marathon WBA. Overall, the highest Kdvalues for pertechnetate were achieved using the strongbase resins in solutions of the lowest carbonate concentration. Pretreatingthe resins in higher carbonate concentrations before use was shownto increase the Kdvalues for pertechnetate.The measured Kdvalues for uranium generallywere low, resulting in high selectivity for the separation of pertechnetatefrom uranium in carbonate solutions. [ABSTRACT FROM AUTHOR]