Effect of Oxygen-Donor Charge on Adjacent Nitrogen-Donor Interactions in Eu3+ Complexes of Mixed N,O-Donor Ligands Demonstrated on a 10-Fold [Eu(TPAMEN)]3+ Chelate Complex
Effect of Oxygen-Donor Charge on Adjacent Nitrogen-Donor Interactions in Eu3+ Complexes of Mixed N,O-Donor Ligands Demonstrated on a 10-Fold [Eu(TPAMEN)]3+ Chelate Complex
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DOI：
10.1021/acs.inorgchem.0c03405
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发表时间：
2021-01-27
影响因子：
4.6
通讯作者：
Fujisawa, Kiyoshi
中科院分区：
文献类型：
--
作者：
Schnaars, Kathleen;Kaneko, Masashi;Fujisawa, Kiyoshi
为了减少核电站产生的高放射性有毒废物，必须使用高选择性的次锕系元素分离剂。N，N，N '，N'-四[（6-羧基吡啶-2-基）甲基]乙二胺（H（4）TPAEN; 1）作为掩蔽剂在Am3+/Eu 3+分离研究中表现出良好的性能。调整吡啶基骨架以提高亲水性导致选择性降低和M3+-N-am相互作用降低。一个增强的碱性的吡啶基N-供体给出了作为一个原因。在这项工作中，我们研究了O-供体碱度的降低是否可以促进M3+-N-am相互作用。因此，我们用中性酰胺基团取代TPAEN（4-）中去质子化的“带电”羧酸基团，并引入N，N，N '，N'-四[（6-N“，N”-二乙基氨基甲酰基吡啶-2-基）甲基]乙二胺（TPAMEN; 2）作为新的配体。TPAMEN与Eu（OTf）、Eu（NO3）（3）中心点6 H（2）O结晶形成带正电荷的1：1 [Eu（TPAMEN）]（3+）固态配合物。将M-O/N键距的改变与[Eu（TPAEN）]（-）进行比较，并通过DFT计算进行研究，以揭示铕（III）处的电荷/能量密度分布以及TPAEN（4-）和TPAMEN的供体官能团的差异。在对Eu和潜在的Am和Cm配合物中的键级、原子电荷自旋布居和态密度进行估计的基础上，分析了施主-金属相互作用的具体贡献.通过对[M（TPAEN）]（-）和[M（TPAMEN）]（3+）（M3+ = Eu 3+，Am 3+）配合物形成能差的预测，对TPAMEN在Am 3 +/Eu 3+分离中的潜在性能进行了展望。
To reduce high-level radiotoxic waste generated by nuclear power plants, highly selective separation agents for minor actinides are mandatory. The mixed N,O-donor ligand N,N,N',N'-tetrakis[(6-carboxypyridin-2-yl)methyl] ethylenediamine (H(4)TPAEN; 1) has shown good performance as a masking agent in Am3+/Eu3+ separation studies. Adjustments on the pyridyl backbone to raise the hydrophilicity led to a decrease in selectivity and a decrease in M3+-N-am interactions. An enhanced basicity of the pyridyl N-donors was given as a cause. In this work, we examine whether a decrease in O-donor basicity can promote the M3+-N-am interactions. Therefore, we replace the deprotonated "charged" carboxylic acid groups of TPAEN(4-) by neutral amide groups and introduce N,N,N',N'-tetrakis[(6-N '',N ''-diethylcarbamoylpyridin-2-yl)methyl]ethylenediamine (TPAMEN; 2) as a new ligand. TPAMEN was crystallized with Eu(OTf),, and Eu(NO3)(3)center dot 6H(2)O to form positively charged 1:1 [Eu(TPAMEN)](3+) complexes in the solid state. Alterations in the M-O/N bond distances are compared to [Eu(TPAEN)](-) and investigated by DFT calculations to expose the differences in charge/energy density distributions at europium(III) and the donor functionalities of the TPAEN(4-) and TPAMEN. On the basis of estimations of the bond orders, atomic charges spin populations, and density of states in the Eu and potential Am and Cm complexes, the specific contributions of the donor-metal interaction are analyzed. The prediction of complex formation energy differences for the [M(TPAEN)](-) and [M(TPAMEN)](3+) (M3+ = Eu3+, Am3+) complexes provide an outlook on the potential performance of TPAMEN in Am3+/Eu3+ separation.