Crystal structures of two new carbazole derivatives: 12-(4-nitrophenyl)-7-phenylsulfonyl-7H-benzofuro[2,3-b]carbazole and 2-methyl-4-(4-nitrophenyl)-9-phenylsulfonyl-9H-thieno[2,3-b]carbazole

The title compounds, C30H18N2O5S, (I), and C27H18N2O4S2, (II), are carbazole derivatives with a phenylsulfonyl group and a nitrophenyl group attached to the carbazole moiety in identical positions in both molecules. A benzofuran ring system in (I) and a methylthiophene ring in (II) are fused with the respective carbazole moieties on the same sides. The mean plane of the carbazole ring system makes a dihedral angle of 3.17 (7)° with the benzofuran ring system in (I) and a dihedral angle of 3.39 (11)° with the methylthiophene ring in (II), implying that both fused units are essentially planar. The mean planes of the carbazole ring systems in both the compounds are almost orthogonal to the respective nitro-substituted phenyl rings, making dihedral angles of 75.64 (10) and 77.63 (12)° in compounds (I) and (II), respectively. In (I), the phenylsulfonyl ring system is positionally disordered with a refined occupancy ratio of 0.63 (2):0.37 (2). In both compounds, the molecular structures are stabilized by intramolecular C—H...O hydrogen bonds, generating S(6) ring motifs with the sulfone group O atoms. In the crystal of compound (I), molecules are linked by pairs of C—H...O hydrogen bonds, which generate R22(18) inversion dimers, and interconnected by C(14) chains running along the c-axis direction, whereas in compound (II), the C—H...O hydrogen bonds generate R43(37) ring motifs. In the crystals of both compounds, C—H...O hydrogen-bonded sheets are formed lying parallel to (10-1). In addition, C—H...π and offset π–π interactions [intercentroid distance = 3.7158 (14) Å in (I) and 3.9040 (15) Å in (II)] are also present in the crystals of both compounds