Synthesis, characterization and supramolecular synthons in crystals of new derivatives of 10-oxa-4-azatricyclo[5.2.1.0[super]2,6]dec-8-ene-3,5-dione

In the study of supramolecular synthons formed by the imide group, four polycyclic imides ( 2- 5) with unsubstituted NH group have been synthesized. The parent compound ( 1), obtained previously, and its derivatives 2- 5 have been characterized by an elemental analysis, FTIR, [super]1H NMR, [super]13C NMR and X-ray crystallography methods. The differences in supramolecular structure were discussed on the basis of the X-ray analysis and the solid-state IR spectra. Selected theoretical calculations of vibrational spectra and binding energies confirm the observations that follow from experiment. In particular, the observed splittings of bands corresponding to C[double bond; length as m-dash]O stretching vibrations in the solid-state IR spectra of 1, 2 and 5 are well predicted by quantum chemical calculations. The molecules 1- 5, having chiral centers, crystallize in centrosymmetric space groups as racemic compounds. In the solid state the association motifs of the imide fragments seem to be related to the structure (molecular shape and substituents) of the interacting molecules. The strongest interactions are the N sub(imide-H...O) sub(i)mide/epoxy hydrogen bonds. They stabilize cyclic dimers ( 1, 2), infinite chains ( 3, 5) and other patterns ( 4) in crystal architecture. Additionally, in the crystals electrostatic interactions involving C[double bond; length as m-dash]O groups are observed; they form parallel ( 1) and anti-parallel ( 3, 4) motifs.