Crystal structures and Hirshfeld surface analyses of methyl 4-{2,2-di-chloro-1-[(E)-phenyl-diazen-yl]eth-enyl}benzoate, methyl 4-{2,2-di-chloro-1-[(E)-(4-methyl-phen-yl)diazen-yl]ethen-yl}benzoate and methyl 4-{2,2-di-chloro-1-[(E)-(3,4-di-methyl-phen-yl)diazen-yl]ethen-yl}benzoate

The crystal structures and Hirshfeld surface analyses of three similar azo compounds are reported. Methyl 4-{2,2-di-chloro-1-[(E)-phenyl-diazen-yl]ethen-yl}benzoate, C16H12Cl2N2O2, (I), and methyl 4-{2,2-di-chloro-1-[(E)-(4-methyl-phen-yl)diazen-yl]ethen-yl}benzoate, C17H14Cl2N2O2, (II), crystallize in the space group P21/c with Z = 4, and methyl 4-{2,2-di-chloro-1-[(E)-(3,4-di-methyl-phen-yl)diazen-yl]ethen-yl}benzoate, C18H16Cl2N2O2, (III), in the space group P with Z = 2. In the crystal of (I), mol-ecules are linked by C-H⋯N hydrogen bonds, forming chains with C(6) motifs parallel to the b axis. Short inter-molecular Cl⋯O contacts of 2.8421 (16) Å and weak van der Waals inter-actions between these chains stabilize the crystal structure. In (II), mol-ecules are linked by C-H⋯O hydrogen bonds and C-Cl⋯π inter-actions, forming layers parallel to (010). Weak van der Waals inter-actions between these layers consolidate the mol-ecular packing. In (III), mol-ecules are linked by C-H⋯π and C-Cl⋯π inter-actions forming chains parallel to [011]. Furthermore, these chains are connected by C-Cl⋯π inter-actions parallel to the a axis, forming (01) layers. The stability of the mol-ecular packing is ensured by van der Waals forces between these layers.

Crystal structures and Hirshfeld surface analysis of 2-(adamantan-1-yl)-5-(4-fluoro-phen-yl)-1,3,4-oxa-diazole and 2-(adamantan-1-yl)-5-(4-chloro-phen-yl)-1,3,4-oxa-diazole

The crystal structures of the title adamantane-oxa-diazole hybrid compounds, C18H19FN2O (I) and C18H19ClN2O (II), are built up from an adamantane unit and a halogenophenyl ring, [X = F (I), Cl (II)], in position 5 on the central 1,3,4-oxa-diazole unit. The mol-ecular structures are very similar, only the relative orientation of the halogenophenyl ring in comparison with the central five-membered ring differs slightly. In the crystals of both compounds, mol-ecules are linked by pairs of C-H⋯N hydrogen bonds, forming inversion dimers with R 2 2(12) ring motifs. In (I) the dimers are connected by C-H⋯F inter-actions, forming slabs lying parallel to the bc plane. In (II), the dimers are linked by C-H⋯π and offset π-π inter-actions [inter-planar distance = 3.4039 (9) Å], forming layers parallel to (10).

Crystal structure of (5-chloro-2-hy-droxy-phen-yl)(3-methyl-isoxazolo[5,4-b]pyridin-5-yl)methanone

In the title compound, C₁₄H₉ClN₂O₃, the fused pyridine and isoxazole rings are approximately planar, making a dihedral angle of 1.14 (16)°. The mol­ecule is twisted with the benzene ring and the mean plane through the fused pyridine-isoxazole ring system being inclined to one another by 47.03 (13)°. There is an intra­molecular O—H⋯O hydrogen bond forming an S(6) ring motif. In the crystal, mol­ecules are linked by C—H⋯N hydrogen bonds, forming chains propagating along [001]. The chains are linked by slipped parallel π–π inter­actions, involving inversion-related benzene rings, forming slabs lying parallel to the bc plane {inter-centroid distance = 3.770 (2) Å].

Crystal structure of ethyl 4-(2,4-di-chloro-phen-yl)-2-methyl-4H-benzo[4,5]thia-zolo[3,2-a]pyrimidine-3-carboxyl-ate

In the title compound, C20H16Cl2N2O2S, the pyrimidine ring has a screw-boat conformation. The attached di-chloro-phenyl ring is twisted at an angle of 89.29 (13)° with respect to the pyrimidine ring mean plane. The benzo-thia-zole group is approximately planar (r.m.s. deviation = 0.008 Å) and inclined to the pyrimidine ring mean plane by 3.04 (10)°. The carboxyl-ate group assumes an extended conformation with respect to the pyrimidine ring, which can be seen from the O=C-O-C torsion angle of 3.2 (4) °. In the crystal, mol-ecules are linked via C-H⋯O and C-H⋯N hydrogen bonds, forming slabs lying parallel to (100).