How Amidoximate Binds the Uranyl Cation

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)x(OH2)y]2–x (x = 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.