Hydrogen-Bond Accepting Strength of Five-Membered N-Heterocycles: The Case of Substituted Phenylpyrrolines and Myosmines - UMR 3495 MAP Accéder directement au contenu
Article Dans Une Revue European Journal of Organic Chemistry Année : 2009

Hydrogen-Bond Accepting Strength of Five-Membered N-Heterocycles: The Case of Substituted Phenylpyrrolines and Myosmines

Résumé

The hydrogen-bond (HB)accepting strengths of a series of five-membered N-heterocycles have been measured in CCl4 solution and/or calculated by theoretical methods. These molecules present a great chemical versatility, ranging from very weak pi bases up to strongly HB acceptors, imines and amines. Among these compounds, special attention has been paid to myosmines, which are bifunctional molecules containing two very similar pyridinic and pyrrolinic sp(2) nitrogen atoms. Infrared measurements provided the global HB basicities of these molecules, but the individual accepting strength of each nitrogen atom could not be achieved experimentally and had to be determined by theoretical calculations. Owing to their flexibility, the geometries of their different isomers were optimized and their basicities weighted by the calculated relative populations. To accurately estimate the individual HB strength of a nitrogen site, it was necessary to take into account a specific halogen bond between the second nitrogen atom and a solvent molecule. I-Pyrroline is a significantly stronger base than pyridine, but irrespective of the substituent on the pyridine ring, the pyrrolinic site is always the weakest HB acceptor in the myosmine molecules. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Domaines

Chimie

Dates et versions

hal-02143935 , version 1 (29-05-2019)

Identifiants

Citer

Virginie Arnaud, Michel Berthelot, Francois-Xavier Felpin, Jacques Lebreton, Jean-Yves Le Questel, et al.. Hydrogen-Bond Accepting Strength of Five-Membered N-Heterocycles: The Case of Substituted Phenylpyrrolines and Myosmines. European Journal of Organic Chemistry, 2009, 29, pp.4939-4948. ⟨10.1002/ejoc.200900569⟩. ⟨hal-02143935⟩
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