Simultaneous effect of geometrical isomerism and chelate ring size of tris(aminocarboxylato)cobalt(III) complexes on their behaviour in thin-layer chromatography on silica gel and alumina

Abstract

The simultaneous effects of geometrical isomerism and chelate ring enlargement of octahedral complexes on their R F values obtained by chromatographing twelve isomers of complexes of the general formula [Co(gly) 3-α (β-ala) n ] ( n = 0–3; glyH = glycine; β-alaH = β-alanine) on thin layers of silica gel and alumina by using five monocomponent solvent systems was investigated. It was found that in most instances the effect of the ring size was predominant. Within the series of facial or meridional isomers it was established that with the enlargement of the chelate ring the R F values of the complexes decreased on silica gel but increased on alumina, which was ascribed to the formation of hydrogen bonds of different strengths between the complexes and the adsorbent.