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, [CoAm3], where Am is glycinato, beta-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. (C) 1999 Elsevier Science B.V. All rights reserved.