How amidoximate binds the uranyl cation

This study identifies how the amidoximate anion, AO, interacts with the uranyl cation, UO ₂ ²⁺. Density functional theory calculations have been used to evaluate possible binding motifs in a series of [UO ₂(AO) _x(OH ₂) _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 η ² binding with the N-O bond. The theoretical results establish the η ² motif to be the most stable form. This prediction is confirmed by single-crystal X-ray diffraction of UO ₂ ²⁺ complexes with acetamidoxime and benzamidoxime anions.