Effects of Water Molecules on Metal Complexes of Hydroxyoxime and Carboxylic Acid Extractants

Water molecules around the cobalt(II) (Co) and manganese(II) (Mn) complexes of the hydroxyoxime extractant, LIX63 and/or of the carboxylic acid extractant, Versatic acid 10 (VA10), in cyclohexane solvent were investigated using molecular dynamics calculations with simulated annealing. For the complexes of VA10, water molecules were coordinated to the metal ions, and VA10 molecules were found around the complexes. For the complexes of LIX63, a few water molecules were located at ~ 0.4 nm from the metal ions, in addition to the LIX63 molecules were also coordinated to the metal ions. Our trajectory analysis indicates that the water molecules at ~ 0.4 nm are hydrogen-bonded to LIX63 or other water molecules, suggesting that the hydrogen bonding contributes to the stabilization of the metal complex.