Thin-layer chromatography of facial and meridional isomers of Co(III) and Cr(III) complexes on polyacrylonitrile sorbent

Abstract

The effect of facial–meridional geometrical isomerism of metal complexes on their chromatographic behaviour on a thin layer of polyacrylonitrile sorbent was examined. To that purpose the three following series of complexes were chromatographed: [Co(eddp)Am], where eddp is ethylenediamine-N,N′-3-propionato ligand, Am is glycinato, alaninato, valinato, leucinato, isoleucinato or isobutyrato ligands, [CoAm 3], where Am is glycinato, β-alaninato, valinato or leucinato ligands as well as two pairs of isomer complexes of [Macacphac 3] type, where M is Co(III) or Cr(III) and acacphac is 1-phenyl-1,3-butanedionato ion. For their chromatographic separation four mono- and thirteen polycomponent solvent systems were used. In all the examined cases meridional isomers were found to exhibit higher hR F values than corresponding facial isomers. Finally, some possible separation mechanisms are discussed.