Janicki Rafał, Siczek Miłosz, Starynowicz Przemysław
University of Wrocław, Faculty of Chemistry, F. Joliot Curie 14, 50-383 Wrocław, Poland.
J Phys Chem Lett. 2024 Sep 26;15(38):9723-9737. doi: 10.1021/acs.jpclett.4c01903. Epub 2024 Sep 17.
Experimental electron density distribution of the [C(NH)][Gd(EDTA)F]·HO crystal was determined. The derived experimental and theoretical (DFT) topological parameters such as ∇ρ, ρ, bond degree (BD), kinetics, and potential energy were used to study the nature of Gd-O, Gd-F, and Gd-N interactions. The natural charge of the Gd is 1.86; the natural configuration of the cation is [Xe]6s4f5d, and the covalency of the Gd-L bond is mainly connected with the transfer of charge from the sp ligand orbitals onto the 5d orbitals of the Gd cation. Simultaneously, the donation of charge onto the 6s and 4f orbitals occurs to a lesser extent. Moreover it was found that the donation of the ligand charges onto the Gd(III) is larger for compounds with a lower coordination number. The obtained topological parameters were analyzed in the context of the Gd(III) f-f transition properties, i.e., energy of the excited L states, Judd-Ofelt intensity parameters, and luminescence lifetimes, of 18 Gd(III) compounds with various O, N, and F donor ligands (DOTA, EDTA, CDTA, DTPA, NTA, EGTA, ODA, F, HO, and CO). The calculated nephelauxetic β parameter may reflect the penetration degree of electron lone pairs of ligands inside the metal basin. Finally, it was found for the first time that the sum of the Gd(III)-L bond energy (∑) is correlated with the position of the gravity center of the S → L transitions and increase of covalency of the Gd(III)-L bonds is associated with decrease of their bond energy. The obtained results may shed light on chemical bonding in systems containing f-elements. Such subtle differences in the covalent contribution to the Ln-L or An-L bond may tune the selectivity of the partitioning processes of lanthanides and actinides.
测定了[C(NH)][Gd(EDTA)F]·HO晶体的实验电子密度分布。利用推导得到的实验和理论（密度泛函理论，DFT）拓扑参数，如∇ρ、ρ、键级（BD）、动力学和势能，研究Gd-O、Gd-F和Gd-N相互作用的本质。Gd的自然电荷为1.86；阳离子的自然构型为[Xe]6s4f5d，Gd-L键的共价性主要与电荷从sp配体轨道转移到Gd阳离子的5d轨道有关。同时，电荷向6s和4f轨道的转移程度较小。此外，还发现对于配位数较低的化合物，配体向Gd(III)的电荷转移更大。在18种含有不同O、N和F供体配体（DOTA、EDTA、CDTA、DTPA、NTA、EGTA、ODA、F、HO和CO）的Gd(III)化合物的Gd(III) f-f跃迁性质（即激发L态的能量、Judd-Ofelt强度参数和发光寿命）的背景下，对获得的拓扑参数进行了分析。计算得到的电子云扩大化β参数可以反映配体孤对电子在金属盆地内的渗透程度。最后，首次发现Gd(III)-L键能之和（∑）与S→L跃迁重心的位置相关，Gd(III)-L键共价性的增加与其键能的降低有关。所得结果可能有助于揭示含f元素体系中的化学键。Ln-L或An-L键共价贡献的这种细微差异可能会调节镧系元素和锕系元素分配过程的选择性。
