Effect of Electronegativity of Donor Atoms on R F Values of Tris(15-diketonato) Complexes of Cobalt(Ill), Chromium(Ill) and Ruthenium(Ill) by Thin-Layer Chromatography on Silica Gel

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-l,3-propanedionato ion and phacphSac = 3-mercapto-l,3-diphenyl-prop-2-en- 1-on ion (n = 0-3). Development was with nine single and six two-component solvent systems. The RF values of the complexes increase by replacing one oxygen atom of a beta-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