Yu Xiaojuan, Sergentu Dumitru-Claudiu, Feng Rulin, Autschbach Jochen
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, United States.
Inorg Chem. 2021 Dec 6;60(23):17744-17757. doi: 10.1021/acs.inorgchem.1c02374. Epub 2021 Nov 6.
A comprehensive ab initio study of periodic actinide-ligand bonding trends for trivalent actinides is performed. Relativistic density functional theory (DFT) and complete active-space (CAS) self-consistent field wavefunction calculations are used to dissect the chemical bonding in the [AnCl], [An(CN)], [An(NCS)], [An(SPMe)], [An(DPA)], and [An(HOPO)] series of actinide (An = U-Es) complexes. Except for some differences for the early actinide complexes with DPA, bond orders and excess 5f-shell populations from donation bonding show qualitatively similar trends in 5f active-space CAS vs DFT calculations. The influence of spin-orbit coupling on donation bonding is small for the tested systems. Along the actinide series, chemically soft vs chemically harder ligands exhibit clear differences in bonding trends. There are pronounced changes in the 5f populations when moving from Pu to Am or Cm, which correlate with previously noted "breaks" in chemical trends. Bonding involving 5f becomes very weak beyond Cm/Bk. We propose that Cm(III) is a borderline case among the trivalent actinides that can be meaningfully considered to be involved in ground-state 5f covalent bonding.
对三价锕系元素的周期性锕系元素-配体键合趋势进行了全面的从头算研究。采用相对论密度泛函理论（DFT）和完全活性空间（CAS）自洽场波函数计算来剖析锕系元素（An = U-Es）配合物的[AnCl]、[An(CN)]、[An(NCS)]、[An(SPMe)]、[An(DPA)]和[An(HOPO)]系列中的化学键合。除了早期锕系元素与DPA形成的配合物存在一些差异外，5f活性空间CAS计算与DFT计算中，来自给体键合的键级和过量5f壳层电子占据呈现出定性相似的趋势。对于所测试的体系，自旋轨道耦合对给体键合的影响较小。沿着锕系元素系列，化学性质较软与化学性质较硬的配体在键合趋势上表现出明显差异。从Pu到Am或Cm时，5f电子占据有显著变化，这与先前指出的化学趋势“突变”相关。超过Cm/Bk后，涉及5f的键合变得非常弱。我们提出，Cm(III)是三价锕系元素中的一个临界情况，可以有意义地认为其参与了基态5f共价键合。
