NMR studies of mixed-ligand lanthanide complexes in solution: Pseudorotation and ring inversion of 18-crown-6 molecule in cerium subgroup chelates

Sergey P. Babailov, Lubov D. Nikulina

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

1H and 13C NMR measurements are reported for the CDCl3 and CD2Cl2 solutions of [La(NO 3)3(18-crown-6)] (I), [Pr(NO3) 3(18-crown-6)] (II) and [Ce(NO3)3(18-crown-6)] (III) complexes. Temperature dependencies of the 1H NMR spectra of II have been analyzed using the dynamic NMR methods for multi-site exchange. Two types of conformational dynamic processes in II were identified (the first one with activation enthalpy ΔH=26 ± 4 kJ/mol is conditioned by interconversion of complex enantiomeric form and pseudorotation of macrocycle molecule upon the C2 symmetry axis, the second one with ΔH=46 ± 5 kJ/mol is conditioned by macrocycle molecule inversion). Studies of the values of the lanthanide-induced shifts revealed that the structure of complexes in solution is similar to that reported for the complex I in the crystal state.

Original languageEnglish
Pages (from-to)103-109
Number of pages7
JournalJournal of Inclusion Phenomena and Macrocyclic Chemistry
Volume51
Issue number1
DOIs
Publication statusPublished - Feb 2005
Externally publishedYes

Keywords

  • 18-crown-6
  • Complexes of lanthanides
  • Crown ethers
  • Dynamic NMR
  • Enthalpy of activation
  • Interconversion of enantiomers
  • Inversion and pseudorotation of macrocycle molecule
  • Molecular dynamics
  • Multi-site exchange
  • Twelve-site exchange

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

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