Retention Behavior of Metal p-Diketonates in Gas-Liquid Chromatography

Abstract

, Gas-liquid chromatographic retention behavior of Be (II), Cu (II), Al (III) and Cr (III) chelates of β-diketones (R₁-CO-CH (R₂) -CO-R₃) was investigated on Apiezon L and Silicone oil F- 50 columns. In each series of metal chelates of the homologous ligands, linear relationship was found to hold between the logarithm of the retention volume (V_R^o-V_G) and the carbon number of the central alkyl group (R₂) or that of the terminal one (R₃) in the ligands. The slopes of the lines are substantially equal, irrespective of the coordination structure of the central metal ion. It seems that the slopes correspond to the increased free energy change due to the increased number of carbon atoms. The intercept of the line varies from a metal to another as far as examined, giving a parameter characteristic to the kind of the central metal ion.