In recent years, the extraction of actinides from high‐level liquid waste is a key step in nuclear waste disposal. However, it is difficult to separate and extract adjacent trivalent actinides An (III) due to similar electron configuration in outer layers. Therefore, studying the law of the bonding between ligands and actinides is essential for designing robust ligands. Here, we demonstrate the in‐group transuranic actinides separation ability of 2‐(2‐amino‐2‐oxoethoxy) acetic acid (HL) through quasi‐relativistic density functional theory (DFT). In the acidic environment of HCl, the extraction of An (III) is governed by cation‐exchange mechanism, forming the complexes [ML2 (H2O)2]+(M = Np, Pu, Am, Cm, Bk) with the deprotonated L− anion during the extraction process. Through calculating the molecular structure and thermodynamic properties of the complexes [ML2 (H2O)2]+, it shows that there exists weak covalent interaction between trivalent transuranic metal ions and ligands L−. Both electrostatic potential and molecular orbital analyses of the ligand L− indicate that the n‐dodecane is an excellent organic solvent for extraction of actinide ions than cyclohexanone. Bonding nature analysis validates that the interaction between An (III) and ligand L− gradually weakens from Np to Cm, and then strengthens from Cm to Bk. The peculiar extraction property of Cm3+ may be connected with its unique electronic structure. Our study may provide reference for understanding the bonding between actinides and ligands, and explore the extraction properties of ligands in different organic solvents, aiming at designing more efficient ligands for the separation of actinides.

The separation of trivalent lanthanides and actinides remains a challenge in the processing of nuclear waste because of their chemical similarities. Revealing the bonding nature of the lanthanide/ actinide ions with ligands in the complexes is essential for designing robust ligands for lanthanides/ actinides separation. In this work, the bonding and separation properties of the scorpion-type ligands (tri(1H-pyrazol-3-yl)methane) with Am(III)/Eu(III) were studied using a relativistic density functional method. To study the substituent effect the electron-withdrawing (À Br and À CF 3 ) and electron-donating (À CH 3 and À OCH 3 ) substituents are introduced into the pyrazole ring to regulate the electron density of the coordinating N atom. The NBO, AIM and thermodynamic analyses show that Am(III) formed stronger bonds with the ligands than Eu(III), and the difference between Am(III) and Eu(III) was mainly due to the stronger bonding ability of Am 5 f orbitals than Eu 4 f orbitals. Analysis of the properties of the ligand and the metal-N bond in the complex shows that the electron-donating substituents increase the electron density on the donor N atom and thus make the formed metal-N bond shorter and stronger, while the electron-withdrawing substituents have the opposite effect. Thermodynamic analysis showed that these ligands had good separation effect for Am and Eu.

With the development of green chemistry, it is necessary to extract the minor actinides from toxic high-level liquid waste. Hence, we need to explore the nature of bonding between ligands...