Aminopolycarboxylates of rare earths. X. 1H-NMR spectroscopic study of the mechanism of dissociation of ethylenediamine-N,N,N′,N′-tetraacetate complexes of cerium(III) and yttrium(III)

G. Laurenczy, L. Radics, E. Brücher

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10 Citations (Scopus)

Abstract

The 1H-NMR signal of the carboxy methylene protons in Ceedta- or Yedta- is AB multiplet. On formation of the protonated complexes in solutions with lower pH, the multiplet signals are broadened. By means of line-shape analysis, the pH-dependence of the average lifetime (τ) before exchange of the carboxy methylene protons HA and HB was determined (at various temperatures in the case of Ceedta-). The dependence of the rate of the AB exchange process (1/τ) on the H+ ion concentration can be described by a similar relation as for the rate of the proton-catalyzed dissociation of the complexes. On the basis of the rate constants it is assumed that the proton-catalyzed AB exchange process of the carboxy methylene protons in Ceedta- and Yedta- occurs via formation of the same intermediates as in the proton-catalyzed dissociation of Ceedta- and Yedta-. The rate-determining step is also the same in the AB exchange and in the dissociation of the complexes; this is probably the formation of an intermediate containing one free protonated iminodiacetate group.

Original languageEnglish
Pages (from-to)219-223
Number of pages5
JournalInorganica Chimica Acta
Volume75
Issue numberC
DOIs
Publication statusPublished - 1983

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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