Solid-State and Solution-State Coordination Chemistry of Lanthanide(III) Complexes with 伪-Hydroxyisobutyric Acid

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• 作者：Xiao-Yan Chen ; George S. Goff ; William C. Ewing ; Brian L. Scott ; Wolfgang Runde
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：December 17, 2012
• 年：2012
• 卷：51
• 期：24
• 页码：13254-13263
• 全文大小：546K
• 年卷期：v.51,no.24(December 17, 2012)
• ISSN：1520-510X

文摘

Despite the wide range of applications of 伪-hydroxyisobutyric acid (HIBA) in biochemical processes, pharmaceutical formulations, and group and elemental separations of lanthanides and actinides, the structures and geometries of lanthanide鈥揌IBA complexes are still not well understood. We reacted HIBA with lanthanides in aqueous solution at pH = 5 and synthesized 14 lanthanide鈥揌IBA complexes of the formula [Ln(HIBA)<sub>2sub>(H<sub>2sub>O)<sub>2sub>](NO<sub>3sub>)路H<sub>2sub>O (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鈥?b>7, 10, and 11) and powders (8, 9, and 12鈥?4). 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鈥揌o, and Er鈥揕u. Solution characterization using <sup>13sup>C NMR further confirmed a single solution complex under the crystallization conditions. Raman and UV鈥搗is鈥揘IR absorbance and diffuse reflectance spectra of HIBA鈥揕n(III) complexes were also measured.