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Three series of tris(β-diketonato) complexes of cobalt(III), chromium(III) and ruthenium(III), in which acetylacetonato ligands were successively replaced with dibenzoylmethanato ligands, were chromatographed on silica gel thin layers and the corresponding mechanisms were considered. The RF values increased with non-aqueous and decreased with aqueous solvent systems. It was established that unmodified silica gel can be used as a sorbent for both normal- and reversed-phase chromatography of metal complexes. The earlier rule of a linear dependence between the RM values of tris(chelate) transition metal complexes and the number of substituted chelate ligands by others was extended.

The RF values of 78 cobalt(III) and platinum(II) complexes have been determined using solvent systems containing phenols. When the complexes were chromatographed with solvent systems containing mono- or polyhydric phenols, the trans isomers were found to exhibit higher RF values than those of the cis isomers, i.e., to display “the phenol effect”. However, by gradually decreasing the phenol content of a solvent system the phenol effect was found to disappear; in the cases of solvent systems containing small amounts of phenol, the addition of an electrolyte, or increasing its concentration, has a similar influence. The RF values of the cobalt(III) complexes increase when a five-membered ring is substituted by a six-membered one, and there is a linear relationship between the RM values and the number of substituted rings. For homologous series of cobalt(III) complexes, the RF values increase with increasing number of C atoms in the branched chain of the ligand and there is a linear relationship between the RM values and the number of C atoms in the aminocarboxylato ligand. Finally, in the cases of four pairs of diastereomeric cobalt(III) complexes, containing l-aminocarboxylato ligands,'the diastereomers having absolute configuration Λ exhibit higher RF values than those of absolute configuration Δ.

The RF values of eight pairs of facial and meridional of cobalt(III) and chromium(III) complexes have been determined by thin-layer chromatography with 21 solvent systems and by paper chromatography with 26 solvent systems. In the thin-layer chromatographic separations on silica gel the meridional isomers always exhibited higher RF values when single component solvent systems were used. On the contrary, with multicomponent solvent systems, in 30% of cases the elution order of the isomers was reversed. In paper chromatographic separations with solvent systems not containing strong acids the meridional isomers were found to exhibit higher RF values. However, when solvent systems containing strong acids were used in some cases the elution order was reversed. Possible mechanisms for the separation of those isomers are considered.