Lutoshkin Maxim A, Petrov Alexander I, Malyar Yuriy N, Kazachenko Alexandr S
Institut de Recherches sur la Catalyse et l'Environnement de Lyon, Université de Claude Bernard Lyon 1, CNRS, IRCELYON, Villeurbanne 69626, France.
Institute of Chemistry and Chemical Technology, Federal Research Center "Krasnoyarsk Science Center Siberian Branch Russian Academy of Sciences (SB RAS)", Krasnoyarsk 660036, Russian Federation.
Inorg Chem. 2021 Mar 1;60(5):3291-3304. doi: 10.1021/acs.inorgchem.0c03717. Epub 2021 Feb 11.
In this work, we demonstrate the fundamental relationships between stability constants and periodic, acid-base, and structural parameters for complexes of some 1,3-diketones. The four analogues of hexafluoroacetylacetone-2-thenoyltrifluoroacetone, 2-furoyltrifluoroacetone, benzoyltrifluoroacetone, and 2-naphthyltrifluoroacetone-have been studied as chelating ligands for 16 rare-earth metals (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in aqueous solutions. Systems have been investigated spectrophotometrically using a multiwave nonlinear least-squares regression algorithm for data processing. Conditional stability constants were obtained for a wide pH region (2.0-5.4) at constant ionic strength ( = 0.5 M, NaCl). To receive the apparent ("true") equilibrium parameters, acid-base and keto-enol characteristics of the studied ligands have been described and revised for specific conditions. Dissociation constants were obtained in citrate-phosphate buffer media and protonation parameters were received in concentrated hydrochloric acid by the Cox-Yates method. The apparent formation constants for monocomplex species were obtained as thermodynamic invariants (depend only on the temperature) for each ligand and lie from 4.2 to 12.7 logarithmic units. Although the studied ligands have similar values of p, the stabilities of their complexes vary considerably. Systematic analysis of 64 apparent stability constants demonstrates that the force of interaction between the metals and nonsymmetric β-diketones increases as 2-furoyltrifluoroacetone < 2-thenoyltrifluoroacetone < benzoyltrifluoroacetone < 2-naphthyltrifluoroacetone. The studied ligands display varying degrees of the correlation between the periodic parameters and formation constants. Naphthyltrifluoroacetone and its complexes with heavy lanthanides exhibit a clear trend in properties with increasing ionic potential. In general, the received set of data can be described from purely electrostatic grounds within the framework of the periodic law. Spectral, keto-enol, acid-base, and complexing properties were reproduced using density functional theory modeling and explain some of the regularities discovered.
在本研究中，我们阐述了某些1,3 - 二酮配合物的稳定常数与周期、酸碱及结构参数之间的基本关系。研究了六氟乙酰丙酮 - 2 - 噻吩甲酰三氟丙酮、2 - 呋喃甲酰三氟丙酮、苯甲酰三氟丙酮和2 - 萘甲酰三氟丙酮这四种类似物作为16种稀土金属（钪、钇、镧、铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱和镥）在水溶液中的螯合配体。使用多波非线性最小二乘回归算法对体系进行分光光度法研究以处理数据。在恒定离子强度（(I = 0.5 M)，(NaCl)）下，针对较宽的pH范围（2.0 - 5.4）获得了条件稳定常数。为得到表观（“真实”）平衡参数，对所研究配体的酸碱和酮 - 烯醇特性进行了描述并针对特定条件进行了修正。通过Cox - Yates方法在柠檬酸 - 磷酸盐缓冲介质中获得解离常数，并在浓盐酸中获得质子化参数。对于每种配体，单配合物物种的表观形成常数作为热力学不变量（仅取决于温度）获得，其对数单位在4.2至12.7之间。尽管所研究的配体具有相似的(p)值，但其配合物的稳定性差异很大。对64个表观稳定常数的系统分析表明，金属与不对称β - 二酮之间的相互作用力按2 - 呋喃甲酰三氟丙酮＜2 - 噻吩甲酰三氟丙酮＜苯甲酰三氟丙酮＜2 - 萘甲酰三氟丙酮的顺序增加。所研究的配体在周期参数与形成常数之间表现出不同程度的相关性。萘甲酰三氟丙酮及其与重镧系元素的配合物随着离子势增加呈现出明显的性质趋势。总体而言，在周期律框架内，所得到的数据集可以从纯粹的静电角度进行描述。使用密度泛函理论建模重现了光谱、酮 - 烯醇、酸碱和络合性质，并解释了所发现的一些规律。
