ISSN:
1434-193X
Keywords:
Conformation analysis
;
Dynamic NMR spectroscopy
;
Crown compounds
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The conformations of (±)-trans-2,3-Bis(1-naphthyl)-15-crown-5 (1) and -18-crown-6 (2) are investigated by MM2 and dynamic 1H-NMR spectroscopy. The most stable conformation is the diequatorial one in both the free ligands and the alkali metal complexes 1 · NaClO4 and 2 · KClO4. Three rotamers, pseudo-aa, pseudo-ee, and pseudo-ae, with respect to the spatial arrangement of the naphthyl groups, were found as calculated minima by MM2 and experimentally by low-temperature NMR, with fair agreement of the rotational barriers. In the cation-reinforced crowns the rotation rates are significantly diminished. The distribution of the rotamers depends on the size of the crown and its state, free or complexed.
Type of Medium:
Electronic Resource
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