NMR relaxation studies in solutions of transition metal complexes. IX. Dynamics of equilibria in aqueous solutions of some copper(II)nitrilotriacetate-B ligand mixed ligand complexes

F. Debreczeni, I. Nagypál

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Abstract

The formation constants of the complexes formed in the copper(II)-nitrilotriacetate (NTA3- parent and in the copper(II)-NTA3--glycinate, copper(II)-NTA3--ammonia and copper(II)-NTA3--methylamine mixed ligand equilibrium systems in aqueous solution have been determined by pH-metry at 25°C in 1 M KCl. The dynamics of equilibria have been studied using the NMR relaxation technique. The glycinate ligand is thought to be more loosely bound to the central copper(II) ion in the mixed complex than in the parent one. In spite of this the ligand exchange rate is much slower, thus the thermodynamic stabilization is reflected in the increase of the kinetic stability of the mixed ligand complex also. The surprisingly high molar relaxation coefficient of the CuNTANH3 mixed complex is interpreted by the fast formation and dissociation of the mixed ligand complex, {A figure is presented} with a forward rate constant of 2.1 × 108 M-1 s.

Original languageEnglish
Pages (from-to)61-65
Number of pages5
JournalInorganica Chimica Acta
Volume72
Issue numberC
DOIs
Publication statusPublished - 1983

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Coordination Complexes
Metal complexes
Transition metals
Copper
transition metals
Ligands
Nuclear magnetic resonance
aqueous solutions
copper
nuclear magnetic resonance
ligands
Relaxation Therapy
Thermodynamics
Ammonia
ammonia
Rate constants
Stabilization
stabilization
dissociation
Ions

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

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title = "NMR relaxation studies in solutions of transition metal complexes. IX. Dynamics of equilibria in aqueous solutions of some copper(II)nitrilotriacetate-B ligand mixed ligand complexes",
abstract = "The formation constants of the complexes formed in the copper(II)-nitrilotriacetate (NTA3- parent and in the copper(II)-NTA3--glycinate, copper(II)-NTA3--ammonia and copper(II)-NTA3--methylamine mixed ligand equilibrium systems in aqueous solution have been determined by pH-metry at 25°C in 1 M KCl. The dynamics of equilibria have been studied using the NMR relaxation technique. The glycinate ligand is thought to be more loosely bound to the central copper(II) ion in the mixed complex than in the parent one. In spite of this the ligand exchange rate is much slower, thus the thermodynamic stabilization is reflected in the increase of the kinetic stability of the mixed ligand complex also. The surprisingly high molar relaxation coefficient of the CuNTANH3 mixed complex is interpreted by the fast formation and dissociation of the mixed ligand complex, {A figure is presented} with a forward rate constant of 2.1 × 108 M-1 s1̄.",
author = "F. Debreczeni and I. Nagyp{\'a}l",
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T1 - NMR relaxation studies in solutions of transition metal complexes. IX. Dynamics of equilibria in aqueous solutions of some copper(II)nitrilotriacetate-B ligand mixed ligand complexes

AU - Debreczeni, F.

AU - Nagypál, I.

PY - 1983

Y1 - 1983

N2 - The formation constants of the complexes formed in the copper(II)-nitrilotriacetate (NTA3- parent and in the copper(II)-NTA3--glycinate, copper(II)-NTA3--ammonia and copper(II)-NTA3--methylamine mixed ligand equilibrium systems in aqueous solution have been determined by pH-metry at 25°C in 1 M KCl. The dynamics of equilibria have been studied using the NMR relaxation technique. The glycinate ligand is thought to be more loosely bound to the central copper(II) ion in the mixed complex than in the parent one. In spite of this the ligand exchange rate is much slower, thus the thermodynamic stabilization is reflected in the increase of the kinetic stability of the mixed ligand complex also. The surprisingly high molar relaxation coefficient of the CuNTANH3 mixed complex is interpreted by the fast formation and dissociation of the mixed ligand complex, {A figure is presented} with a forward rate constant of 2.1 × 108 M-1 s1̄.

AB - The formation constants of the complexes formed in the copper(II)-nitrilotriacetate (NTA3- parent and in the copper(II)-NTA3--glycinate, copper(II)-NTA3--ammonia and copper(II)-NTA3--methylamine mixed ligand equilibrium systems in aqueous solution have been determined by pH-metry at 25°C in 1 M KCl. The dynamics of equilibria have been studied using the NMR relaxation technique. The glycinate ligand is thought to be more loosely bound to the central copper(II) ion in the mixed complex than in the parent one. In spite of this the ligand exchange rate is much slower, thus the thermodynamic stabilization is reflected in the increase of the kinetic stability of the mixed ligand complex also. The surprisingly high molar relaxation coefficient of the CuNTANH3 mixed complex is interpreted by the fast formation and dissociation of the mixed ligand complex, {A figure is presented} with a forward rate constant of 2.1 × 108 M-1 s1̄.

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