Article révisé par les pairs
Résumé : We present some properties of NMR first order spectra in relation with the permutational character of intramolecular rearrangements. We use the symmetry properties of the effective spin hamiltonian in order to analyse the Kubo‐Sack exchange matrices. In this context, we propose the experimental study of two molecules and we show that this study could give rise to new information about the permutational character of the rearrangements responsible for their non‐rigidity. Copyright © 1977 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim