title: Complexation behavior of Eu(III) and Am(III) with CMPO and Ph2CMPO ligands: insights from density functional theory.
abstract: A series of extraction complexes of Eu(III) and Am(III) with CMPO (n-octyl(phenyl)-N,N-diisobutyl-methylcarbamoyl phosphine oxide) and its derivative Ph2CMPO (diphenyl-N,N-diisobutyl carbamoyl phosphine oxide) have been studied using density functional theory (DFT). It has been found that for the neutral complexes of 2:1 and 3:1 (ligand/metal) stoichiometry, CMPO and Ph2CMPO predominantly coordinate with metal cations through the phosphoric oxygen atoms. Eu(III) and Am(III) prefer to form the neutral 2:1 and 3:1 type complexes in nitrate-rich acid solutions, and in the extraction process the reactions of [M(NO3)(H2O)7](2+) + 2NO3(-) + nL → ML(n)(NO3)3 + 7H2O (M = Eu, Am; n = 2, 3) are the dominant complexation reactions. In addition, CMPO and Ph2CMPO show similar extractability properties. Taking into account the solvation effects, the metal-ligand binding energies are obviously decreased, i.e., the presence of solvent may have an significant effect on the extraction behavior of Eu(III) and Am(III) with CMPOs. Moreover, these CMPOs reagents have comparable extractability for Eu(III) and Am(III), confirming that these extractants have little lanthanide/actinide selectivity in acidic media.
authors.affiliation: Nuclear Energy Nano-Chemistry Group, Key Laboratory of Nuclear Radiation and Nuclear Energy Technology and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences , Beijing 100049, China.
authors.forename: Cong-Zhi
authors.initials: CZ
authors.lastname: Wang
authors.forename: Wei-Qun
authors.initials: WQ
authors.lastname: Shi
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Lan
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Zhao
authors.forename: Yue-Zhou
authors.initials: YZ
authors.lastname: Wei
authors.forename: Zhi-Fang
authors.initials: ZF
authors.lastname: Chai