Mechanismus der Bildung und des Zerfalls von Amidkomplexen, I Kupfer (II) und N, N′‐Diglycylpropylendiamin

Abstract

Swwnary. The kinetics o f thc formation and dissociation of the copper(I1) complex with X, N'-Diglycyl-propylendiainine has been studied. In the formation reaction an interrncdiate mas observed, the structure and reactivity of which is discussed. The rate of dissociation of the complex is proportional to [H+l2. This is explained by a rapid proton addition to one of the amino groups, followed by the slow reaction of a second proton with the coordinated amide group. The effect of acetate buffer, which increases the dissociation rate, is tliscussed.In einer fruheren Arbeit [l] wurde die Gleichgewichtsreaktion zwischen Cu2+ und einer homologen Reihe von Bisamiden (I) untersucht. Dabei zeigte sich, dass Cuzf,

Formation and dissociation mechanism of amide complexes. V. Interconversion of dimeric and monomeric Cu2+‐complexes with 1,8‐diamino‐3,6‐diaza‐2,7‐octanedione: Comparison between the reactivity of terminal and internal amide groups

“…Similarly Margerum et al [3] have also proposed for L=TRIGLY that the carboxylate dissociates prior to the protonation of the amide group. Finally, in the case of L = 1,9-diamino-3,7-diazanonanedione a preequilibrium with the formation of the species 7 was postulated to explain the protonation of CuLH-, [6]. Thus, in all cases in which an internal amide group is blocked in its rotation by two chelate rings, the protonation of the coordinated amide group seems only possible if one of the chelate rings opens so that free rotation can occur.…”

“…Thus the overall protonation reaction can be described by Equations 2 and 3 from right to left. The first step of the protonation has an unusual rate law given by Equation 6 ~ (6) with a bimolecular dependence on CuLH-,. The experimental points are given in Figure 5.…”

“…Part Iv, [ 11 with that of an amide included into the backbone of the ligand, we have studied R-NH-CO-CHz-NH-CH2-CH2-CH2-NH-CH2-CO-NH-R l R = H 2 R = E t the complexes of 1,9-diamino-3,7-diaza-2,8-nonanedione with Cu2+ [6] and Ni2+ [7]. However, since the Cu2+-complex of this ligand dissociates or adds the two amide protons in one step, no direct comparison was possible.…”