Interactions of vanadium(iv) with amidoxime ligands: redox reactivity†
The use of amidoxime-functionalized polymer fibers as a sorbent for uranium has attracted recent interest for the extraction of uranium from seawater. Vanadium is one of the main competing ions for uranium sorption as V(V) species, however, vanadium is also present as V(IV) in seawater. In the present study, the interactions of V(IV) with amidoxime and similar ligands were explored. Attempts were made to synthesize V(IV) complexes of glutaroimide-dioxime, a molecular analogue of polymer sorbents. However, V(IV) was found to react irreversibly with glutaroimide-dioxime and other oxime groups, oxidizing to the V(V) oxidation state. We have explored the reactions and propose mechanisms, as well as characterized the redox behavior of the vanadium–glutaroimide-dioxime complex.