Solution state structure and equilibria of lanthanide (fod)3 complexes revisited: A 1H, 13C and 19F nuclear magnetic resonance study of Eu(fod)3,Magnetic Resonance in Chemistry

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Solution state structure and equilibria of lanthanide (fod)3 complexes revisited: A 1H, 13C and 19F nuclear magnetic resonance study of Eu(fod)3
Magnetic Resonance in Chemistry ( IF 1.9 ) Pub Date : 2021-03-17 , DOI: 10.1002/mrc.5151
Gábor Szalontai ₁

Affiliation

In a qualitative approach, variable temperature ¹H, ¹⁹F and ¹³C nuclear magnetic resonance (NMR) were used to characterize the solution state structure and equilibria of the widely used lanthanide solvent reagent Eu(fod)₃. Despite the fact that the side chain fluorines are far from the coordination site, the ¹⁹F–¹H NMR spectra turned out to be sensitive reporters of self-coordination and/or adduct formation with other ligands. For example, they predict/explain immediately the otherwise hardly predictable magnitude of the expectable paramagnetic effects. The temperature-dependent Fermi-contact effects observed in the ¹³C{¹H} spectra were extremely important aides in their assignments. The equilibria could be manipulated by changing the solvent used and/or the reagent/ligand molar ratio. Depending on their coordination ability, the solvents possess a certain control over the adduct life times. Sharpening of the ¹⁹F signals in the presence of associative solvent molecules such as dimethyl sulfoxide (DMSO) or CH₃CN is an indication of changing complex structure (shifting the equilibrium towards the monomeric form). In apolar solvents, relaxation and diffusion data confirmed the oligomerization of the Eu(fod)₃–d₂₇ chelate complexes already at relatively low (≥3.0 mg/0.4 ml) concentration.

中文翻译：

重新审视镧系元素 (fod)3 配合物的溶液状态结构和平衡：Eu(fod)3 的 1H、13C 和 19F 核磁共振研究

在定性方法中，可变温度¹ H、¹⁹ F 和¹³ C 核磁共振 (NMR) 用于表征广泛使用的镧系元素溶剂试剂 Eu(fod) ₃的溶液状态结构和平衡。尽管侧链氟远离配位位点，但¹⁹ F– ¹ H NMR 光谱结果是自配位和/或与其他配体形成加合物的敏感报告者。例如，他们立即预测/解释了可预期的顺磁效应的其他难以预测的幅度。在¹³ C{ ¹H} 光谱在他们的任务中是极其重要的助手。可以通过改变使用的溶剂和/或试剂/配体摩尔比来操纵平衡。根据它们的协调能力，溶剂对加合物的寿命有一定的控制。在缔合溶剂分子如二甲亚砜 (DMSO) 或 CH ₃ CN存在下¹⁹ F 信号的锐化表明复杂结构发生变化（平衡向单体形式移动）。在非极性溶剂中，弛豫和扩散数据证实了 Eu(fod) ₃ -d ₂₇螯合物的低聚反应已经在相对较低的 (≥3.0 mg/0.4 ml) 浓度下进行。

更新日期：2021-03-17

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