In the title compound, C(12)H(12)ClNO(2)S, the S atom is displaced by 0.708 (2) Å out of the plane through the remaining atoms of the thia-zine ring (r.m.s. deviation = 0.0823 Å). This plane makes a dihedral angle of 89.33 (7)° with the phenyl ring. In the crystal, adjacent mol-ecules are connected through C-H⋯O hydrogen bonds into layers parallel to the bc plane.

In the title compound, C17H15FO2S, the benzo-furan ring system, being essentially planar, with an r.m.s. deviation from the least-squares plane of 0.009 (2) Å, makes a dihedral angle of 79.02 (5)° with the plane of the 2-fluoro-phenyl group. In the crystal, mol-ecules are linked by pairs of weak C-H⋯O hydrogen bonds into centrosymmetric dimers.

In the title compound, C(16)H(28)N(3)O(4), the plane of the pyrrolidine ring system is twisted with respect to the plane of the nitronyl nitroxide unit, making a dihedral angle of 79.80 (6)°. The crystal structure is stabilized by C-H⋯O hydrogen bonds.

In the title compound, C(19)H(15)NO, the N atom adopts an approximately trigonal-planar geometry, lying 0.07 (1) Å from the plane defined by its three neighbouring C atoms. The two phenyl rings and the benzaldehyde group form dihedral angles of 53.0 (1)/47.2 (1) and 29.0 (1)°, respectively, with this central plane.

In the title compound, C16H16Cl2N4, the imidazole ring mean plane makes a dihedral angle of 70.01 (1)° with the phenyl ring. The Cl atoms deviate by -0.0472 (6) and 0.0245 (8) Å from the plane of their attached benzene ring. In the crystal, mol-ecules are linked via pairs of C-H⋯N hydrogen bonds, forming inversion dimers.

The dihedral angle between the two aromatic ring systems in the title compound, C(15)H(12)N(2)O, is 85.9 (1)°; The angle at the O atom is widened to 118.2 (2)°. The quinoxalin-yloxy part of the mol-ecule lies on a mirror plane and the tolyl group is disordered over two positions about the mirror plane.

The title compound, C(9)H(10)N(2)O(2)S, was obtained from the treatment of ethyl 4-cyano-3-hydr-oxy-5-morpholinothio-phene-2-carboxyl-ate with concentrated HCl. The mean plane of the essentially planar dihydro-thio-phene ring is almost orthogonal to the mirror plane of the N-morpholine substituent, making a dihedral angle of 87.2 (2)°.

In the title compound, C(23)H(22)N(2), the dihedral angle between the methyl-benzene groups is 77.62 (6)°, and the dihedral angle between the envelope-shaped pyrazole ring [in which one C atom displaced by 0.109 (1) Å from the mean plane of the other four atoms] and the phenyl ring is 17.57 (7)°. The dihedral angles between the phenyl ring and the two methyl-benzene rings are 13.24 (6) and 81.0...

The asymmetric unit of the title compound, C14H8Cl2N4O2, contains one half-mol-ecule, the complete mol-ecule being generated by the operation of a twofold rotation axis. The Cl atom deviates significantly from the plane of the pyrazine ring [0.0215 (4) Å]. The central benzene ring makes a dihedral angle of 72.82 (7)° with the plane of the pyrazine ring.

The title compound, C28H40N2, was obtained from the condensation reaction of 4-tert-butyl-2,6-di-methyl-aniline and butane-2,3-dione. The mol-ecule lies on an inversion centre. The C=N bond has an E conformation. The plane of the benzene ring is almost perpendicular to the 1,4-di-aza-butadiene mean plane [dihedral angle = 89.8 (9)°].