Dynamic NMR study of the flexibility of 2-amino-3-aroyl-4,6-diaryl-pyrylium salts |
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| Authors: | Matthias Heydenreich Andreas Koch E Kleinpeter and Thomas Zimmermann |
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| Institution: | (1) Universit?t Potsdam, Institut für Organische Chemie und Strukturanalytik, Am Neuen Palais 10, D-14415 Potsdam, Germany, DE;(2) Institut für Organische Chemie der Universit?t Leipzig, Projektgruppe P2, Permoserstr. 15, D-04303 Leipzig, Germany, DE |
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| Abstract: | Dynamic NMR investigations of a number of 2-amino-3-aroyl-4,6-diaryl-pyrylium salts were carried out. The barrier to rotation
of the partial C, N double bond was determined and proved to be in the range of 62 to 63 kJ/mol. Quantum chemical calculations
of bond orders and electron densities of the different atoms in the molecules show the distinct double bond character of the
exocyclic C, N bond. This is in agreement with the relatively high barrier to rotation. By quantum chemical ab initio 3-21G
calculations, the dynamic behaviour of this kind of compounds was simulated; two pairs (image and mirror image) of ground
state conformations, in coincidence with the experiment, were obtained.
Received: 10 May 1996 / Revised: 1 July 1996 / Accepted: 4 July 1996 |
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