Die Komplexbildung der neutralen Amidgruppe mit Cu²⁺ in wässeriger Lösung

Abstract

Suvnmary. The interaction between Cu2+ and the terdentate ligands N-picolinoyl-ethylenediamine, glycine-2-pyridylmethylamide, Na-(Z-pyridylmethyl)-glycinamide and Na-(Z-pyridylmethyl)-glycine-ethylamide, respectively, has been studied by spectrophotometry and potentiomctry. At high pH values the ionised amide group undergoes complex formation and the resulting chclates have similar structures and stabilities. In slightly acidic solution however, each ligand gives rise to a different species. These facts are explaincd by assuming that the neutral amide group coordinates through its carbonyl oxygen atom. The stability constant and the absorption spectrum of each complex have been calculated by computer programmes.Rontgen-Strukturanalysen zeigen, dass Amide mit Cu2+ und anderen d-MetallIonen zwei Arten von Komplexen bilden, indem entweder der Carbonylsauerstoff sein Elektronenpaar zur Verfugung stellt (I) oder das Stickstoffatorn der deprotonierten Amidgruppe gebunden wird (11) [l]

Transition metal ions and amides. Part 7. Apical interactions in copper(II) complexes. Stability and structure of the binary and ternary copper(II) complexes formed with L-alaninamide and diethylenetriamine in aqueous solution

“…20,48"51 The present data for the binary dien complexes agree well with those of earlier studies. 22,29 It is instructive to compare first the absorption maxima of some Cu2+ complexes that have four N donors equatorially coordinated with only a solvent interaction in the two apical positions;44 within the following series the maxima are shifted toward shorter wavelengths: Cu(NH3)42+ (Table II, no. 16) > Cu(dien)(NH3)2+ (no.…”

“…The equilibrium constants of the complexes were determined under the same conditions with the additional presence of 0.00294 M CuS04; hence, 1:2 complexes are not important under these conditions but they were considered in the calculations by using the corresponding constants published earlier. 22 The titration solutions (25 mL) of the mixed-ligand systems were 0.00294 M in CuS04, 0.0030 M in dien-3HCl, and 0.0030, 0.0060, or 0.0090 M in AlaA-HCl. All experiments were done twice, and the final result is the average of the calculations based on two independent sets of experiments.…”

“…The four-coordinate planar d8 complexes are, in principle, coordinately unsaturated, and the possibility of loose coordination in the axial position will greatly increase the probability of finding the free end of the diamine in the vicinity of the Pt(II). The (22) F, A. Cotton and F. E. Harris, J. Phys.…”

Ternary Complexes in Solution, XII. Models for Biological Mixed-Ligand Complexes: 2,2′-Bipyridyl-Cu2+-Oligoglycine Systems

“…The third amino group may w T eakly interact with an apical position as is known from other Cu 2+ -amine complexes 47 . In fact, such an apical interaction is also suggested for the Cu 2+ -diethylenetriamine 1: 2 complex 48 .…”

Synthesis and Characterization of New Mono-N-functionalized Tetraaza Macrocyclic Nickel(II) and Copper(II) Complexes

“…[16][17][18][19][20][21][22][23] ): 3320 (ν N-H ) and 2230 (ν C≡N ). Although mass spectrum of the product shows a main peak corresponding to L 11 , it also contains a small amount of uncharacterized by-product(s).…”