Jensen Mark P, Bond Andrew H
Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
J Am Chem Soc. 2002 Aug 21;124(33):9870-7. doi: 10.1021/ja0178620.
The complexes of trivalent actinide (Am(III) and Cm(III)) and lanthanide (Nd(III) and Sm(III)) cations with bis(2,4,4-trimethylpentyl)phosphinic acid, bis(2,4,4-trimethylpentyl)monothiophosphinic acid, and bis(2,4,4-trimethylpentyl)dithiophosphinic acid in n-dodecane have been studied by visible absorption spectroscopy and X-ray absorption fine structure (XAFS) measurements in order to understand the chemical interactions responsible for the great selectivity the dithiophosphinate ligand exhibits for trivalent actinide cations in liquid-liquid extraction. Under the conditions studied, each type of ligand displays a different coordination mode with trivalent f-element cations. The phosphinate ligand coordinates as hydrogen-bonded dimers, forming M(HL2)3. Both the oxygen and the sulfur donor of the monothiophosphinate ligand can bind the cations, affording both bidentate and monodentate ligands. The dithiophosphinate ligand forms neutral bidentate complexes, ML3, with no discernible nitrate or water molecules in the inner coordination sphere. Comparison of the Cm(III), Nd(III), and Sm(III) XAFS shows that the structure and metal-donor atom bond distances are indistinguishable within experimental error for similarly sized trivalent lanthanide and actinide cations, despite the selectivity of bis(2,4,4-trimethylpentyl)dithiophosphinic acid for trivalent actinide cations over trivalent lanthanide cations.
为了理解二硫代膦酸酯配体在液 - 液萃取中对三价锕系阳离子表现出高选择性的化学相互作用，通过可见吸收光谱和X射线吸收精细结构（XAFS）测量研究了三价锕系元素（镅（III）和锔（III））以及镧系元素（钕（III）和钐（III））阳离子与双（2,4,4 - 三甲基戊基）次膦酸、双（2,4,4 - 三甲基戊基）单硫代次膦酸和双（2,4,4 - 三甲基戊基）二硫代次膦酸在正十二烷中的配合物。在所研究的条件下，每种配体与三价f元素阳离子显示出不同的配位模式。次膦酸酯配体以氢键连接的二聚体形式配位，形成M(HL2)3。单硫代次膦酸酯配体的氧和硫供体都可以与阳离子结合，产生双齿和单齿配体。二硫代膦酸酯配体形成中性双齿配合物ML3，在内层配位球中没有可辨别的硝酸根或水分子。锔（III）、钕（III）和钐（III）的XAFS比较表明，尽管双（2,4,4 - 三甲基戊基）二硫代膦酸对三价锕系阳离子比对三价镧系阳离子具有选择性，但对于尺寸相似的三价镧系和锕系阳离子，其结构和金属 - 供体原子键距在实验误差范围内无法区分。
