How Amidoximate Binds the Uranyl Cation

Abstract

This study identifies how the amidoximate anion, AO, interacts with the uranyl cation, UO₂²⁺. Density functional theory calculations have been used to evaluate possible binding motifs in a series of [UO₂(AO)_<i>x</i>(OH₂)_<i>y</i>]^2–<i>x</i> (<i>x</i> = 1–3) complexes. These motifs include monodentate binding to either the oxygen or the nitrogen atom of the oxime group, bidentate chelation involving the oxime oxygen atom and the amide nitrogen atom, and η² binding with the N–O bond. The theoretical results establish the η² motif to be the most stable form. This prediction is confirmed by single-crystal X-ray diffraction of UO₂²⁺ complexes with acetamidoxime and benzamidoxime anions