Aminopolycarboxylates of rare earths. 14. Equilibrium and 1H NMR studies on the Lanthanide(III)-ethylenebis(oxyethylenedinitrilo)-tetraacetate complexes

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Abstract

pH-Potentiometric and photometric investigations indicate that in the presence of excess ligand in the lanthanide(III)-egta systems Ln(egta)25- complexes are formed in addition to the well-known Lnegta- complexes. Similar studies proved the formation of the ternary complexes Ln(egta)(imda)3-. The stability constants have been determined from pH-potentiometric data and the values obtained practically agree for the whole series of lanthanides for both types of complexes. Spectral changes show that in both the complexes Ln(egta)25- and Ln(egta)(imda)3-, the second ligand is coordinated by similar functional groups. The proton chemical shifts obtained for the Lnegta- complexes indicate the coordination of the two ether oxygen atoms. The multiplet pattern of the spectra, which partly disappears by the coordination of the second ligand, shows a more rigid structure for the Luegta- than for the Laegta-. The formation of the 1:2 and ternary complexes, in accordance with the results of spectrophotometric and 1H NMR studies, has been explained by an increase in the coordination number, connected to a slight increase in the metal-donor atom distances.

Original languageEnglish
Pages (from-to)227-233
Number of pages7
JournalJournal of the Less-Common Metals
Volume112
Issue number1-2
DOIs
Publication statusPublished - 1985

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Lanthanoid Series Elements
Rare earth elements
Rare earths
Ligands
Nuclear magnetic resonance
Rigid structures
Atoms
Chemical shift
Ether
Functional groups
Protons
Ethers
Metals
Oxygen

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title = "Aminopolycarboxylates of rare earths. 14. Equilibrium and 1H NMR studies on the Lanthanide(III)-ethylenebis(oxyethylenedinitrilo)-tetraacetate complexes",
abstract = "pH-Potentiometric and photometric investigations indicate that in the presence of excess ligand in the lanthanide(III)-egta systems Ln(egta)25- complexes are formed in addition to the well-known Lnegta- complexes. Similar studies proved the formation of the ternary complexes Ln(egta)(imda)3-. The stability constants have been determined from pH-potentiometric data and the values obtained practically agree for the whole series of lanthanides for both types of complexes. Spectral changes show that in both the complexes Ln(egta)25- and Ln(egta)(imda)3-, the second ligand is coordinated by similar functional groups. The proton chemical shifts obtained for the Lnegta- complexes indicate the coordination of the two ether oxygen atoms. The multiplet pattern of the spectra, which partly disappears by the coordination of the second ligand, shows a more rigid structure for the Luegta- than for the Laegta-. The formation of the 1:2 and ternary complexes, in accordance with the results of spectrophotometric and 1H NMR studies, has been explained by an increase in the coordination number, connected to a slight increase in the metal-donor atom distances.",
author = "R. Kir{\'a}ly and E. Br{\"u}cher",
year = "1985",
doi = "10.1016/0022-5088(85)90027-X",
language = "English",
volume = "112",
pages = "227--233",
journal = "Journal of Alloys and Compounds",
issn = "0925-8388",
publisher = "Elsevier BV",
number = "1-2",

}

TY - JOUR

T1 - Aminopolycarboxylates of rare earths. 14. Equilibrium and 1H NMR studies on the Lanthanide(III)-ethylenebis(oxyethylenedinitrilo)-tetraacetate complexes

AU - Király, R.

AU - Brücher, E.

PY - 1985

Y1 - 1985

N2 - pH-Potentiometric and photometric investigations indicate that in the presence of excess ligand in the lanthanide(III)-egta systems Ln(egta)25- complexes are formed in addition to the well-known Lnegta- complexes. Similar studies proved the formation of the ternary complexes Ln(egta)(imda)3-. The stability constants have been determined from pH-potentiometric data and the values obtained practically agree for the whole series of lanthanides for both types of complexes. Spectral changes show that in both the complexes Ln(egta)25- and Ln(egta)(imda)3-, the second ligand is coordinated by similar functional groups. The proton chemical shifts obtained for the Lnegta- complexes indicate the coordination of the two ether oxygen atoms. The multiplet pattern of the spectra, which partly disappears by the coordination of the second ligand, shows a more rigid structure for the Luegta- than for the Laegta-. The formation of the 1:2 and ternary complexes, in accordance with the results of spectrophotometric and 1H NMR studies, has been explained by an increase in the coordination number, connected to a slight increase in the metal-donor atom distances.

AB - pH-Potentiometric and photometric investigations indicate that in the presence of excess ligand in the lanthanide(III)-egta systems Ln(egta)25- complexes are formed in addition to the well-known Lnegta- complexes. Similar studies proved the formation of the ternary complexes Ln(egta)(imda)3-. The stability constants have been determined from pH-potentiometric data and the values obtained practically agree for the whole series of lanthanides for both types of complexes. Spectral changes show that in both the complexes Ln(egta)25- and Ln(egta)(imda)3-, the second ligand is coordinated by similar functional groups. The proton chemical shifts obtained for the Lnegta- complexes indicate the coordination of the two ether oxygen atoms. The multiplet pattern of the spectra, which partly disappears by the coordination of the second ligand, shows a more rigid structure for the Luegta- than for the Laegta-. The formation of the 1:2 and ternary complexes, in accordance with the results of spectrophotometric and 1H NMR studies, has been explained by an increase in the coordination number, connected to a slight increase in the metal-donor atom distances.

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U2 - 10.1016/0022-5088(85)90027-X

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