美国橡树岭国家实验室Ivanov, Alexander S.团队报道了溶液中promethium络合物的观察。相关研究成果发表在2024年5月22日出版的《自然》。

镧系稀土金属在现代技术中无处不在，但我们对第61种元素promethium（Pm）的化学成分知之甚少，Pm是一种高放射性且难以接近的镧系元素。尽管Pm很重要，但它明显没有出现在镧系元素的实验研究中，阻碍了人们对所谓的镧系元素收缩现象的全面理解：这是一般化学教科书中引用的元素周期表的一个基本方面。

该文中，研究人员证明了新合成的有机二甘醇酰胺配体，对水溶液中¹⁴⁷Pm放射性核素（半衰期2.62年）的稳定螯合作用。使用同步加速器X射线吸收光谱和量子化学计算研究了所得的均感Pm_III配合物，以确定Pm的配位结构和键距。这些基本见解使人们能够对一整套同构的镧系元素配合物进行完整的结构研究，最终仅基于实验观察来捕捉溶液中镧系元素的收缩。

研究结果显示，镧系元素开始时键加速缩短，这可能与二甘醇酰胺所显示的分离趋势有关。放射性Pm_III络合物在水环境中的表征加深了人们对镧系元素内部行为，以及f嵌段元素的化学和分离的理解。

附：英文原文

Title: Observation of a promethium complex in solution

Author: Driscoll, Darren M., White, Frankie D., Pramanik, Subhamay, Einkauf, Jeffrey D., Ravel, Bruce, Bykov, Dmytro, Roy, Santanu, Mayes, Richard T., Delmau, Ltitia H., Cary, Samantha K., Dyke, Thomas, Miller, April, Silveira, Matt, VanCleve, Shelley M., Davern, Sandra M., Jansone-Popova, Santa, Popovs, Ilja, Ivanov, Alexander S.

Issue&Volume: 2024-05-22

Abstract: Lanthanide rare-earth metals are ubiquitous in modern technologies1,2,3,4,5, but we know little about chemistry of the 61st element, promethium (Pm)6, a lanthanide that is highly radioactive and inaccessible. Despite its importance7,8, Pm has been conspicuously absent from the experimental studies of lanthanides, impeding our full comprehension of the so-called lanthanide contraction phenomenon: a fundamental aspect of the periodic table that is quoted in general chemistry textbooks. Here we demonstrate a stable chelation of the 147Pm radionuclide (half-life of 2.62years) in aqueous solution by the newly synthesized organic diglycolamide ligand. The resulting homoleptic PmIII complex is studied using synchrotron X-ray absorption spectroscopy and quantum chemical calculations to establish the coordination structure and a bond distance of promethium. These fundamental insights allow a complete structural investigation of a full set of isostructural lanthanide complexes, ultimately capturing the lanthanide contraction in solution solely on the basis of experimental observations. Our results show accelerated shortening of bonds at the beginning of the lanthanide series, which can be correlated to the separation trends shown by diglycolamides9,10,11. The characterization of the radioactive PmIII complex in an aqueous environment deepens our understanding of intra-lanthanide behaviour12,13,14,15 and the chemistry and separation of the f-block elements16.

DOI: 10.1038/s41586-024-07267-6

Source: https://www.nature.com/articles/s41586-024-07267-6