Premium
Dynamic NMR study of the electronic state of heteroaromatics. III —Pyrylium salts or intramolecularly bridged pentamethine cyanines?
Author(s) -
Kleinpeter E.,
Spitzner R.,
Schroth W.,
Pihlaja K.,
Mattinen J.
Publication year - 1988
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260260813
Subject(s) - chemistry , pyridinium , pyridinium compounds , chemical shift , nmr spectra database , carbon 13 nmr , spectral line , proton nmr , nuclear magnetic resonance spectroscopy , computational chemistry , stereochemistry , medicinal chemistry , physics , astronomy
The 13 C NMR spectra and the temperature‐dependent 1 H NMR spectra of a series of NR 2 ‐substituted pyridines and pyrones were studied, and the 13 C chemical shifts and the rotational barriers about the exocyclic partial C,N double bonds were compared with the corresponding values for suitable pyridinium, pyrylium and thiopyrylium salts. The NMR spectroscopic results are discussed in the light of the electronic state and mesomerism in the species studied; the salts in question should be named, from the electronic point of view, more realistically as bridged pentamethine cyanines rather than pyridinium, pyrylium and thiopyrylium salts.