Aminopolycarboxylates of rare earths-V. Kinetics of exchange between Ce(III) and Tb(III) ethylenediaminetetraacetate complexes and the diethylenetriaminepentaacetate ligand

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Abstract

The kinetics of the ligand-exchange reactions between Ceedta and dtpa and between Tbedta and dtpa were studied spectrophotometrically at 25° in the pH range 4.4-6.5. In the Tbedta-dtpa system, the exchange takes place by H+-catalyzed dissociation of the complexes and also by collision of the complexes and the dtpa ligand (dtpa5-, Hdtpa4- and H2dtpa3-). In the Ceedta-dtpa system, attack by the dtpa ligands is very effective, and thus the reaction occurs predominantly via an associative mechanism. The reaction rate increase accompanying elevation of the pH can be interpreted by the higher efficiency of collision with dtpa species containgng less protons. In the reaction of Ceedta, formation of a very rapidly produced intermediate was detected, in which, besides the edta, one of the imda groups of the dtpa is also coordinated. The rate-determining step of the reactions is the further transformation of this mixed ligand complex intermediate, the dissociation of edta from the complex.

Original languageEnglish
Pages (from-to)749-756
Number of pages8
JournalJournal of Inorganic and Nuclear Chemistry
Volume42
Issue number5
DOIs
Publication statusPublished - 1980

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Rare earths
rare earth elements
Ligands
ligands
Kinetics
kinetics
dissociation
collisions
attack
Reaction rates
Protons
Ion exchange
reaction kinetics
protons

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@article{fba8d0b7de774e9eb777795e20f22618,
title = "Aminopolycarboxylates of rare earths-V. Kinetics of exchange between Ce(III) and Tb(III) ethylenediaminetetraacetate complexes and the diethylenetriaminepentaacetate ligand",
abstract = "The kinetics of the ligand-exchange reactions between Ceedta and dtpa and between Tbedta and dtpa were studied spectrophotometrically at 25° in the pH range 4.4-6.5. In the Tbedta-dtpa system, the exchange takes place by H+-catalyzed dissociation of the complexes and also by collision of the complexes and the dtpa ligand (dtpa5-, Hdtpa4- and H2dtpa3-). In the Ceedta-dtpa system, attack by the dtpa ligands is very effective, and thus the reaction occurs predominantly via an associative mechanism. The reaction rate increase accompanying elevation of the pH can be interpreted by the higher efficiency of collision with dtpa species containgng less protons. In the reaction of Ceedta, formation of a very rapidly produced intermediate was detected, in which, besides the edta, one of the imda groups of the dtpa is also coordinated. The rate-determining step of the reactions is the further transformation of this mixed ligand complex intermediate, the dissociation of edta from the complex.",
author = "E. Br{\"u}cher and I. B{\'a}nyai",
year = "1980",
doi = "10.1016/0022-1902(80)80225-9",
language = "English",
volume = "42",
pages = "749--756",
journal = "Polyhedron",
issn = "0277-5387",
publisher = "Elsevier Limited",
number = "5",

}

TY - JOUR

T1 - Aminopolycarboxylates of rare earths-V. Kinetics of exchange between Ce(III) and Tb(III) ethylenediaminetetraacetate complexes and the diethylenetriaminepentaacetate ligand

AU - Brücher, E.

AU - Bányai, I.

PY - 1980

Y1 - 1980

N2 - The kinetics of the ligand-exchange reactions between Ceedta and dtpa and between Tbedta and dtpa were studied spectrophotometrically at 25° in the pH range 4.4-6.5. In the Tbedta-dtpa system, the exchange takes place by H+-catalyzed dissociation of the complexes and also by collision of the complexes and the dtpa ligand (dtpa5-, Hdtpa4- and H2dtpa3-). In the Ceedta-dtpa system, attack by the dtpa ligands is very effective, and thus the reaction occurs predominantly via an associative mechanism. The reaction rate increase accompanying elevation of the pH can be interpreted by the higher efficiency of collision with dtpa species containgng less protons. In the reaction of Ceedta, formation of a very rapidly produced intermediate was detected, in which, besides the edta, one of the imda groups of the dtpa is also coordinated. The rate-determining step of the reactions is the further transformation of this mixed ligand complex intermediate, the dissociation of edta from the complex.

AB - The kinetics of the ligand-exchange reactions between Ceedta and dtpa and between Tbedta and dtpa were studied spectrophotometrically at 25° in the pH range 4.4-6.5. In the Tbedta-dtpa system, the exchange takes place by H+-catalyzed dissociation of the complexes and also by collision of the complexes and the dtpa ligand (dtpa5-, Hdtpa4- and H2dtpa3-). In the Ceedta-dtpa system, attack by the dtpa ligands is very effective, and thus the reaction occurs predominantly via an associative mechanism. The reaction rate increase accompanying elevation of the pH can be interpreted by the higher efficiency of collision with dtpa species containgng less protons. In the reaction of Ceedta, formation of a very rapidly produced intermediate was detected, in which, besides the edta, one of the imda groups of the dtpa is also coordinated. The rate-determining step of the reactions is the further transformation of this mixed ligand complex intermediate, the dissociation of edta from the complex.

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U2 - 10.1016/0022-1902(80)80225-9

DO - 10.1016/0022-1902(80)80225-9

M3 - Article

AN - SCOPUS:4243183987

VL - 42

SP - 749

EP - 756

JO - Polyhedron

JF - Polyhedron

SN - 0277-5387

IS - 5

ER -