Outer-sphere ion clusters are inferred in many important natural and technological processes, but their mechanisms of assembly and solution structures are difficult to define. Here, we characterize trefoil-shaped outer-sphere lanthanide chloride and nitrate ion clusters in hydrocarbon solutions formed during liquid–liquid extraction with diglycolamide ligands. These are assembled through steric and electrostatic forces, where the anions reside in equidistant “clefts” between coordinating diglycolamide ligands in positions that satisfy both repulsive and attractive ion–ion interactions. Our study shows how sterically directed electrostatic interactions may assemble stable outer-sphere ion clusters in organic solutions, elucidating new strategies for controlling ion cluster assembly and extraction.

中文翻译：

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三叶形的外层离子簇与二甘醇酰胺配体介导镧系元素（III）的离子迁移。

在许多重要的自然和技术过程中都可以推断出外层离子簇，但它们的组装机理和溶液结构很难定义。在这里，我们表征了在用二甘醇酰胺配体进行液-液萃取过程中形成的烃溶液中的三叶形外层氯化镧和硝酸根离子簇。它们是通过空间力和静电力组装而成的，其中阴离子位于配位的二甘醇酰胺配体之间的等距“裂缝”中，这些位置同时满足排斥性和吸引性离子-离子相互作用。我们的研究表明，空间定向的静电相互作用如何在有机溶液中组装稳定的外层离子簇，阐明了控制离子簇组装和提取的新策略。