Die Kinetik der Murexid‐Komplexbildung mit Kationen verschiedenen Koordinationscharakters

Abstract

Abstract The kinetics of the reaction of murexide with different divalent metal ions of class A and B have been measured by the temperature‐jump‐relaxation method. The second‐order formation rate constant increases in the sequence Ni 2+ < Co 2+ < Mn 2+ < Zn 2+ < Cd 2+ ˜ Cu 2+ ˜ Ca 2+ < Sr 2+ < Ba 2+ < Pb 2+ . Thermodynamic data obtained from kinetic and equilibrium studies, respectively, are in good agreement. The results are compared with the characteristic rate constants for H 2 O‐exchange in the inner coordination sphere of these metal ions, which follow the same sequence. The rate constants of the reaction of murexide with various trivalent metal ions, including the lanthanides, are also discussed in terms of current ideas on metal complex formation.