Chromium(III) Complexes with Iminodiacetic Acid or <i>l</i>-Aspartic Acid

Abstract

Abstract The formation constants of chromium (III) complexes with iminodiacetic acid (IDA) and l-aspartic acid (Asp) as the terdentate ligands were determined by the pH method in the ionic strength, μ=0.1 and at 25°C: their values were logk1=10.9 and logk2=10.5 for IDA and logk1=10.1 and logk2=9.5 for Asp, respectively. That the overall formation constants of chromium(III)-IDA complexes obtained were slightly larger than those of the corresponding -Asp complexes was explained by the stronger chelate effect in the former complexes than in the latter ones. The solid chromium (III) complexes with IDA and Asp were also prepared. Based on chemical analyses and the conductivity measurement or the behavior toward the ion exchangers, the chemical formulas of these complexes are possibly K[Cr(ida)2]·3H2O and K[Cr(OH)2asp] respectively. X-Ray powder diffraction patterns indicated that the former crystalline complex has tetragonal unit lattice, the axial parameter being a=14.57 and c=12.38 Å, whereas the latter is amorphous solid.