In (2SR,4RS)-7-chloro-2-exo-(4-chloro­phenyl)-2,3,4,5-tetra­hy­dro-1H-1,4-epoxy-1-benzazepine, C16H13Cl2NO, (I), the mol­ecules are linked by a combination of C—H⋯O and C—H⋯N hydrogen bonds into a chain of edge-fused R33(12) rings. The isomeric compound (2S,4R)-7-chloro-2-exo-(2-chloro­phenyl)-2,3,4,5-tetra­hydro-1H-1,4-epoxy-1-benzazepine, (II), crystallizes as a single 2S,4R enantio­mer and the mol­ecules are linked into a three-dimensional framework structure by two C—H⋯O hydrogen bonds and one C—H⋯π(arene) hydrogen bond. The mol­ecules of (2S,4R)-7-chloro-2-exo-(1-naphthyl)-2,3,4,5-tetra­hydro-1H-1,4-epoxy-1-benzazepine, C20H16ClNO, (III), are also linked into a three-dimensional framework structure, here by one C—H⋯O hydrogen bond and two C—H⋯π(arene) hydrogen bonds. The significance of this study lies in its observation of the variations in mol­ecular configuration and conformation, and in the variation in the patterns of supra­molecular aggregation, consequent upon modest changes in the peripheral substituents.