Three styryl-substituted tetrahydro-1,4-epoxy-1-benzazepines: configurations, conformations and hydrogen-bonded chains

2SR,4RS)-7-Chloro-2-exo-[(E)-styryl]-2,3,4,5-tetrahydro-1H1,4-epoxy-1-benzazepine, C18H16ClNO, (I), crystallizes as a racemic twin in the space group P2(1) and the molecules are linked into a chain of edge-fused R-3(3)(9) rings by a combination of C-H center dot center dot center dot O and C-H center dot center dot center dot N hydrogen bonds. The diastereoisomer (2RS,4RS)-7-chloro-2-endo-[(E)-styryl]-2,3,4,5-tetrahydro1H-1,4-epoxy-1-benzazepine, (II), also crystallizes as a racemic twin, but in the space group P2(1)2(1)2(1), and a two-centre C-H center dot center dot center dot N hydrogen bond and a three-centre C-H center dot center dot center dot(O,N) hydrogen bond combine to link the molecules into a complex chain of rings. In (2R,4R)-7-fluoro-2-endo-[(E)styryl]-2,3,4,5-tetrahydro-1H-1,4-epoxy-1-benzazepine, C18H16FNO, (III), which is not isomorphous with (II), the molecules are linked by a single C-H center dot center dot center dot O hydrogen bond into simple chains, but the molecular arrangements in (II) and (III) are nonetheless very similar. The significance of this study lies in its observation of the variations in molecular configuration and conformation, and in the variation in the supramolecular aggregation, consequent upon modest changes in the peripheral substituents.