The effect of the central ion of tris-beta-diketonato complexes of transition metals on their retention on thin layers of silica gel

Abstract

The effect of the central ion of tris-beta-diketonato complexes of transition metals on their hR(F) values in thin layer chromatography (TLC) on silica gel has been investigated for 24 Co(III), Cr(III), and Ru(III) complexes of the types [M(acac)(3-n)(phacphac)(n)] and [M(acac)(3-n)(phacphSac)(n)], where n = 0-3, and with four complexes of the type [M(acac)(3)], where M = Sc(III), Y(III), Nd(III), or La(III), acac is the 2,4-pentanedionato ion, phacphac is the 1,3-diphenyl-1,3-propanedionato ion, and phacphSac is the 3-mercapto-1,3-diphenylprop-2-en-1-one ion. One- and two-component nonaqueous mobile phases were used for the chromatographic separations. The dependence of retention data on the length of ionic radius and on En/r(i) value is discussed. The mobility (hR(F) values) of the tris(acetylacetonato) complexes on thin layers of silica gel is directly proportional to the ionic radius of the central ion. On the basis of the results obtained, adsorption was assumed to be the dominant mechanism of separation under the chromatographic conditions used.