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 language | English |
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Pages (from-to) | 103-109 |
Number of pages | 7 |
Journal | Journal of Inclusion Phenomena and Macrocyclic Chemistry |
Volume | 51 |
Issue number | 1 |
DOIs | |
Publication status | Published - Feb 2005 |
Externally published | Yes |
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