Cao Chang-Su, Zhao Jing, Hu Han-Shi, Schwarz W H Eugen, Li Jun
Theoretical Chemistry Center, Department of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education, Tsinghua University, Beijing 100084, China.
Physical and Theoretical Chemistry Lab, Department of Chemistry and Biology, Faculty of Science and Technology, University of Siegen, Siegen 57068, Germany.
Proc Natl Acad Sci U S A. 2023 Oct 24;120(43):e2303989120. doi: 10.1073/pnas.2303989120. Epub 2023 Oct 19.
The Periodic Law of Chemistry is one of the great discoveries in cultural history. Elements behaving chemically similar are empirically merged in groups of a Periodic Table, each element with valence electrons per neutral atom, and with upper limit for the oxidation and valence numbers. Here, we report that among the usually mono- or di-valent s-block elements ( = 1 or 2), the heaviest members (Fr, Ra, E, and E) with atomic numbers Z = 87, 88, 119, 120 form unusual 5- or 6-valent compounds at ambient conditions. Together with well-reported basic changes of valence at the end of the 6d-series, in the whole 7p-series, and for 5g6f-elements, it indicates that at the bottom of common Periodic Tables, the classic Periodic Law is not as straightforward as commonly expected. Specifically, we predict the feasible experimental synthesis of polyvalent [RaL] ( = 4, 6) compounds.
化学元素周期律是文化史上的重大发现之一。化学性质相似的元素根据经验被归为元素周期表中的族，每个元素的中性原子都有价电子，并且有氧化数和化合价的上限。在此，我们报告，在通常为单价或二价的s区元素（=1或2）中，原子序数Z = 87、88、119、120的最重成员（钫、镭、E和E）在环境条件下形成不寻常的五价或六价化合物。连同6d系列末尾、整个7p系列以及5g6f元素中已充分报道的化合价基本变化一起，这表明在常见元素周期表的底部，经典的元素周期律并不像通常预期的那样简单直接。具体而言，我们预测了多价[RaL]（=4、6）化合物的可行实验合成方法。
