Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Inorg Chem. 2013 Mar 18;52(6):3217-24. doi: 10.1021/ic302696m. Epub 2013 Mar 4.
As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1). 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 (1-3); 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 species in solution and solid state. The different coordination in solid state and solution was verified by distinctive (13)C NMR signals of the carboxylate groups in the solid state NMR.
作为用于锕系元素分离的羧酸官能化任务特异性离子液体 (TSIL) 的前体，(吡唑-1-基)乙酸 (L) 可以作为功能化吡唑盐阴离子脱质子化，以与硬金属阳离子配位。然而，L 与 f 元素的配位化学仍未得到探索。我们在 pH = 5 的水溶液中使 L 与镧系元素反应，合成了四种通式为 [Ln(L)3(H2O)2]·nH2O 的镧系元素配合物（1，Ln = La，n = 2；2，Ln = Ce，n = 2；3，Ln = Pr，n = 2；4，Ln = Nd，n = 1）。所有配合物均通过单晶 X 射线衍射分析进行了表征，揭示了一维链的形成。两种不同的晶体结构由 L 中羧酸盐基团的不同配位模式控制：末端双齿和桥联三齿（1-3）；末端双齿、桥联双齿和三齿配位在 4 中。固态紫外可见近红外漫反射光谱与溶液态紫外可见近红外光谱的比较表明，在溶液和固态中存在不同的物种。固态 NMR 中羧酸盐基团的独特 (13)C NMR 信号证实了固态和溶液态的不同配位。
