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An NMR study of some N ‐arylaminopropenylylidenearylammonium salts
Author(s) -
Richards C. P.,
Webb G. A.
Publication year - 1975
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270070809
Subject(s) - chemistry , salt (chemistry) , ionic bonding , propene , nmr spectra database , ion , spin (aerodynamics) , cis–trans isomerism , ion exchange , proton nmr , derivative (finance) , conjugated system , spectral line , inorganic chemistry , medicinal chemistry , organic chemistry , catalysis , polymer , physics , astronomy , financial economics , economics , engineering , aerospace engineering
The preparation, characterisation and 1 H NMR spectra of some N ‐arylaminopropenylylidenearylammonium salts are reported. The NMR data show that in DMSO the cations exist as conjugated amino–imines, generally as the ‘all‐ trans ’ geometrical isomer. An exception is found in the case of the 4‐nitrophenyl derivative which produces a mixture of the ‘all‐ trans ’ and ‘ cis ‐ trans ’ isomers with slow exchange between them at room temperature. The relative stability of the ‘all‐ trans ’ isomer increases as the salt becomes more ionic. By varying the temperature, pH and nature of the anion it is found that exchange of the NH protons on the cation controls the appearance of spin‐spin coupling between the NH and 1,3‐propene protons.