Restricted rotation around the carbon–nitrogen amide bond in (E)-2-formylthiophene N-acetylhydrazone. X-Ray structures of the resulting conformers

Abstract

The rotation around the C–N amide bond in the title compound produces two conformational isomers trans(1) and cis(2), which have been isolated in the solid state. Their i.r. spectra show significant differences in the 1 800–1 200 cm^–1 region, in particular the disappearance of the amide II band for (2). Their crystal structures have been determined from X-ray diffractometer data to R= 0.051 for both compounds.