Crystallographic Determination of Three Ni-α-Hydroxyoxime-Carboxylic Acid Synergist Complexes

Abstract

X-ray crystal structures of three dicarboxylato-bis-α-hydroxyoximenickel(II) complexes have been obtained. These contain a short chained (C8) analogue of LIX®63 hydroxyoxime, along with either benzoate, isobutyrate or propionate. All have pseudo-octahedral structures with monodentate carboxylate anions located cis to one another and neutral, chelating α-hydroxyoxime ligands. Intra-molecular hydrogen bonding between each anionic acid's carboxylate group and an adjacent oxime hydroxyl group is evident. Inter-molecular hydrogen bonding is also observed. These provide the first definitive structural elucidation of the types of nickel complexes that could be formed during synergistic extraction by LIX®63 and carboxylic acids.

Keywords:

• LIX63
• 5,8-diethyl-7-hydroxydodecan-6-oxime
• Versatic 10
• carboxylic acid
• synergist
• synergistic solvent extraction
• crystal structure
• X-ray

ACKNOWLEDGMENTS

The support of the Minerals Down Under National Research Flagship and Parker CRC for Integrated Hydrometallurgy Solutions (established and supported under the Australian Government's Cooperative Research Centres Program) is gratefully acknowledged. Mr. D. Shiers and Dr. M. Tsuntsaeva obtained the UV spectra of the commercial reagent nickel complexes.