Effect of electronegativity of donor atoms on R_F values of tris(β-diketonato) complexes of cobalt(III), chromium(III) and ruthenium(III) by thin-layer chromatography on silica gel

Summary

The effect of the electronegativity of donor atoms on R_F values obtained by TLC on silica gel was investigated with two series of complexes of the type [M(acac)_3−n(phacphac)_n] and [M(acac)_3−n(phacphSac)_n], where M is Co(III), Cr(III) or Ru(III), acac=2,4-pentandionato ion, phacphac=1,3-diphenyl-1,3-propanedionato ion and phacphSac=3-mercapto-1,3-diphenyl-prop-2-en-1-on ion (n=0–3). Development was with nine single and six two-component solvent systems. The R_F values of the complexes increase by replacing one oxygen atom of a β-diketonato ligand with a less electronegative sulphur atom. A positive linear dependence between the R_M values of the complexes and the numbers of acac substituted by phacphSac ligands was established. The separation mechanisms and separation factors are discussed.