Structural clues to UO₂²⁺/VO₂⁺ competition in seawater extraction using amidoxime-based extractants.

Here we present the first structural comparison of amidoxime complexes of UO2(2+) and VO2(+) (the main competitor in the extraction of uranium from seawater using amidoxime-based sorbents) using a 4,5-di(amidoxime)-functionalized imidazole ligand. The amidoxime groups resist tautomerization in both cases and quite different coordination modes (chelating vs. bridging) are observed.