The Coordination Structure of the Extracted Cobalt(II) Complex with a Synergistic Mixture Containing Lix63 and Versatic10

In the present work, the cobalt(II) synergist complex with isobutyric acid (HLI) and 5-hydroxy-4octanone oxime (HBI), which were the corresponding short-chain analogs of active synergistic mixture of Versatic10 (HL) and Lix63 (5,8-diethyl-7-hydroxy-6-dodecanoneoxime, HB), was prepared and studied by X-ray single-crystal diffraction. The crystal structure of the cobalt(II) synergistic complex showed that the composition of the complex was Co(HBI) 2(LI) 2 with a cis-form octahedron geometry structure. Both intra and intermolecular hydrogen bonding between the uncoordinated carbonyl oxygen atom of the deprotonated monodentate anionic ligand LI and the hydrogen atom of the alpha-hydroxy or the oxime hydroxyl group of HBI were observed in the crystal lattice. In order to bridge the gap between the solid-state structure of the cobalt(II) synergist complex and the solution structure of the extracted cobalt(II) complex with the actual synergistic mixture containing Versatic10 and Lix63 in the nonpolar organic phase, both the cobalt(II) synergistic complex and the extracted cobalt(II) complex were further investigated by Fourier transform infrared spectroscopy (FT-IR) and electrospray ionization mass spectrometry (ESI-MS). The results indicated that the extracted cobalt(II) complex in the nonpolar organic phase might possess a similar coordination structure as that of the cobalt(II) synergist complex.