Abstract
A lack of methods for the separation and determination of air-sensitive Cr(II) and stable Cr(III) complexes in aqueous and organic phase motivated this study. The formation of kinetically stable Cr(III) complexes with common anions was studied using ion chromatography coupled to inductively-coupled plasma emission spectrometry (ICP-OES). Distribution diagrams for the complex species were determined from the results. Estimations of the stability constants were made from these diagrams and compared with stability constants published in the literature.
Separation and determination of Cr(II) and Cr(III) and their complexes with PDCA and EDTA in aqueous phase was investigated using ion chromatography. ICP-OES was used for detection purposes.
The separation and determination of Cr(II) and Cr(III) complexes with a ligand, bis-(2-decylsulphanyl-ethyl)amine, developed by Sasol Technology (Pty) Ltd., was attempted. The study was undertaken as the Cr(III) complex is used as a catalyst in the trimerisation of ethylene to 1-hexene. The mechanism is still unknown and determining which species are present in the catalytic cycle could clarify which oxidation-reduction couple is involved during the cycle. Reversed phase HPLC was investigated as a possible method for the separation of these complexes. No separation of the species was, however, achieved.
Prof. P.P. Coetzee