Stereodynamics and edge-to-face CH-π aromatic interactions in imino compounds containing heterocyclic ringsThis paper is dedicated to the memory of our dear friend and former colleague the late Professor José Sepúlveda-Arques, University of Valencia, who facilitated this international collaboration.Electronic supplementary information (ESI) available: Additional dynamic NMR data, 1H NMR, 13C NMR and mass spectra for compounds 1-8. CCDC 1518494 and 1518495 for compounds 1 and 5. For ESI and cryst

By comparison with close contact interactions between benzene rings there is a paucity of experimental data available for attractive interactions involving aromatic heterocyclic rings, especially for small molecules in solution. Herein we describe aromatic heterocyclic and carbocyclic edge-to face interactions and conformational stereodynamics of N -1,2-diphenylethyl imines bearing a phenyl group and either a 2-pyridyl, 3-pyridyl, 2-thiophene or 2-furanyl moiety on the imino carbon. X-ray crystal structures have been determined for two compounds. Slow rotation about the phenyl-imino bond in the E -isomers and around the heterocycle-imino bond in the Z -isomers of the pyridyl compounds was observed at low temperatures by NMR. Abnormally large shielding of one ortho hydrogen indicates that both the imino phenyl and heterocycle rings can engage in an edge-to-face interaction with the N-terminal phenyl moiety in the appropriate isomer. Some rotational barriers around the phenyl-imino and heterocycle-imino bonds were measured. Imino models show that 6 and 5-membered heterocyclic rings can engage in attractive edge-to-face interactions with an adjacent phenyl ring.