Amidoximes metal complexes

An important use of polymer ligands is the extraction of trace amounts of metals, e.g. gold, uranium, from seawater. For example, an industrial extraction of uranium from seawater has been developed using polymers with amidoxime groups [76]. Also the role of macromolecular metal complexes in Green chemistry is very significant, for example their efficient use in the neutralization of effluents from chemical companies. 

Between the two synthetic schemes, the amidoxime route appears to be the most used and reliable strategy. For instance, oxadiazole systems involved as organometaUic Hgands can be synthesized by precursors already including the complexed metal, such as in the case of ferrocenyl oxadiazoles 18 (2014JOM-C67). The latter is produced from ferrocenyl substituted prop-argyl aldehyde 15 which, after O-functionalization into intermediate 16, undergoes an intramolecular Michael addition into oxadiazoline 17, before elimination of acetaldehyde to yield final product 18 (Scheme 5). 

B. A. Rudenko, Separation of transition and heavy metals on an amidoxime complexing sorbent, J. Chromatogr. A, 671, 51, 1994. 

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