Mixed-donor ligands, such as those containing a combination of O/N or O/S, have been studied extensively for the selective extraction of trivalent actinides, especially Am³⁺ and Cm³⁺, from lanthanides during the recycling of used nuclear fuel. Oxygen/sulfur donor ligand combinations also result from the hydrolytic and/or radiolytic degradation of dithiophosphates, such as the Cyanex class of extractants, which are initially converted to monothiophosphates. To understand potential differences between the binding of such degraded ligands to Nd³⁺ and Am³⁺, the monothiophosphate complexes [M(OPS(OEt)₂)₅(H₂O)₂]^2– (M³⁺ = Nd³⁺, Am³⁺) were prepared and characterized by single-crystal X-ray diffraction and optical spectroscopy and studied as a function of pressure up to ca. 14 GPa using diamond-anvil techniques. Although Nd³⁺ and Am³⁺ have nearly identical eight-coordinated ionic radii, these structures reveal that while the M–O bond distances in these complexes are almost equal, the M–S distances are statistically different. Moreover, for [Nd(OPS(OEt)₂)₅(H₂O)₂]^2–, the hypersensitive ⁴I_9/2 → ⁴G_5/2 transition shifts as a function of pressure by −11 cm^–1/GPa. Whereas for [Am(OPS(OEt)₂)₅(H₂O)₂]^2–, the ⁷F₀ → ⁷F₆ transition shows a slightly stronger pressure dependence with a shift of −13 cm^–1/GPa and also exhibits broadening of the 5f → 5f transitions at high pressures. These data likely indicate an increased involvement of the 5f orbitals in bonding with Am³⁺ relative to that of Nd³⁺ in these complexes.

中文翻译：

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一硫代磷酸镅(III) 和钕(III) 配合物的比较


混合供体配体，例如含有 O/N 或 O/S 组合的配体，已被广泛研究用于选择性提取三价锕系元素，特别是 Am ³⁺ 和 Cm ³⁺ ，来自废核燃料回收过程中的镧系元素。氧/硫供体配体组合也由二硫代磷酸盐的水解和/或辐射分解降解产生，例如Cyanex类萃取剂，其最初转化为单硫代磷酸盐。为了了解此类降解配体与 Nd ³⁺ 和 Am ³⁺ 结合之间的电位差异，单硫代磷酸盐复合物 [M(OPS(OEt) ₂ ) ₅ (H ₂ O) ₂ ] ^2– (M ³⁺ = Nd ³⁺ , Am ³⁺ ）通过单晶 X 射线衍射和光谱进行了制备和表征，并研究了高达 ca 的压力函数。 14 GPa，使用金刚石砧技术。尽管 Nd ³⁺ 和 Am ³⁺ 具有几乎相同的八配位离子半径，但这些结构表明，虽然这些配合物中的 M-O 键距几乎相等，但 M-S 距离统计上有差异。此外，对于 [Nd(OPS(OEt) ₂ ) ₅ (H ₂ O) ₂ ] ^2– ，超敏感 ⁴ I _9/2 → ⁴ G _5/2 转变作为压力的函数移动 -11 cm ^–1 ) ₅ (H ₂ O) ₂ ] ^2– ， ⁷ F ₀ → ⁷ F ₆ 转变显示出稍强的压力依赖性，位移为 -13 cm ^–1 /GPa，并且在高压下还表现出 5f → 5f 转变的展宽。 这些数据可能表明，在这些配合物中，相对于 Nd ³⁺ 而言，5f 轨道与 Am ³⁺ 的结合增加。