Complexation Behavior of Tri‐ <i>n</i> ‐Amyl Phosphate and Di‐ <i>n</i> ‐Amyl‐ <i>n</i> ‐Amyl Phosphonate With U(VI), Th(IV), Zr(IV), Nd(III), and Pd(II): Experimental and Theoretical Insights

In the present study, the extraction behavior of various metal ions using alternate solvents, such as tri‐ n ‐amyl phosphate (TAP) and di‐ n ‐amyl‐ n ‐amyl phosphonate (DAAP), was investigated by applying experimental and theoretical methodologies. Metal ions with different oxidation states, namely U(VI), Th(IV), Zr(IV), Nd(III), and Pd(II), were chosen to understand the versatility of the solvent by comparing its extraction efficiency (distribution data) at different concentrations of nitric acid with 0.5 M TAP and 0.5 M DAAP in n ‐dodecane medium. Due to poor extraction, Pd(II) was further studied with neat extractants. Distribution ratios followed the order U(VI) &gt; Th(IV) &gt; Zr(IV) &gt; Nd(III) &gt; Pd(II), with DAAP exhibiting higher extraction potential than TAP. Density functional theory calculations predicted identical coordination geometries for both extractants and predicted complexation energies consistent with experimental trends. This study is distinctive in directly comparing phosphate (TAP) and phosphonate (DAAP) extractants possessing identical carbon chain lengths and evaluating their interactions with metal ions spanning multiple oxidation states. This integrated experimental–computational approach isolates the effects of extractant functionality and metal charge, providing mechanistic insight into solvent–metal interactions and demonstrating the superior extraction performance of phosphonates for actinides.