Synthesis of cobalt(III) complexes with novel open chain oxime ligands and metal–ligand coordination in aqueous solution

Two open chain oxime ligands (H2pap, N,N′-bis(2-hydroxyiminopropionyl)-1,3-diaminopropane and H2pen, N,N′-bis(2-hydroxyiminopropionyl)-1,2-aminoethane) reveal high efficacy in coordination of Co(II) ions followed by autooxidation to Co(III) under O2. Differences in complexing ability are attributed to the longer –CH2– chain in PAP and better fit of the relatively large Co(II) ion to the accessible binding site.