Résumé : The cis and trans isomers of eight 1,2‐diarylethylenes, precursors of helicenes, have been studied by NMR. spectroscopy. The observed differences in chemical shifts, specific solvent effects and steric effects (bromo derivatives) can be explained by the contribution of ‘helicenelike’ conformers in the cis isomers. Copyright © 1972 Verlag GmbH & Co. KGaA, Weinheim