Parimi Ashutosh, Mosher Emmalee, Schreckenbach Georg
Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
Dalton Trans. 2023 Dec 5;52(47):18035-18044. doi: 10.1039/d2dt02725a.
Due to the limited abundance of the actinide elements, computational methods, for now, remain an exclusive avenue to investigate the periodic trends across the actinide series. As every actinide element can exhibit a +3-oxidation state, we have explored model systems of gas-phase actinide trihalides, phosphates, and arsenates across the series to capture the periodic trends. By doing so, we were able to capture the periodic trends down the halogen series as well, and for the first time we are reporting a study on actinide astatides. Using scalar and spin-orbit relativistic Density Functional Theory (DFT) calculations, we have explored the variations in bond lengths, bond angles, and the charges on actinides (An). Despite the use of different sets of ligands, the trends remain similar. The properties of trivalent Pa, U, Np, and Pu are nearly identical; similar ionic radii could be the reason. The actinide elements show a tendency to exhibit a pre-Pu and a post-Cm behaviour, with Am acting as a switch. This could be due to the change in the behaviour from d-f-type to f-filling/d-type at around Pu-Cm in the actinides as already proposed in the previous literature. Bond lengths in the AnX increase down the halide series, and the atomic charges decrease on the actinide elements.
由于锕系元素的丰度有限，目前计算方法仍是研究整个锕系元素周期趋势的唯一途径。由于每个锕系元素都能呈现 +3 氧化态，我们研究了该系列中气相锕系三卤化物、磷酸盐和砷酸盐的模型体系，以捕捉周期趋势。通过这样做，我们也能够捕捉到整个卤素系列的周期趋势，并且我们首次报道了关于锕系砹化物的研究。使用标量和自旋轨道相对论密度泛函理论（DFT）计算，我们研究了键长、键角以及锕系元素（An）上电荷的变化。尽管使用了不同的配体集，但趋势仍然相似。三价镤、铀、镎和钚的性质几乎相同；相似的离子半径可能是原因。锕系元素呈现出一种在钚之前和锔之后的行为趋势，其中镅起到了转变的作用。这可能是由于如先前文献中所提出的，在锕系元素中钚 - 锔附近行为从 d - f 型转变为 f - 填充/d 型所致。随着卤化物系列向下，AnX 中的键长增加，而锕系元素上的原子电荷减少。
