Eman A. Ahmed

Crystal structure of ethyl 2-{2-[(1Z)-1-hy­droxy-3-(4-nitro­phen­yl)-3-oxoprop-1-en-1-yl]phen­oxy}acetate

The title compound, C19H17NO7, crystallized in a ratio of about 6:4 of the two possible keto–enol forms. This was observed as disorder over the central C3H2O2 unit. The dihedral angle between the rings is 8.2 (2)°.The molecules pack by C—H⋯O interactions in a layered fashion parallel to (-104).

Crystal structure of ethyl 2-[2-((1E)-{(1E)-2-[2-(2-eth­oxy-2-oxoeth­oxy)benzyl­idene]hydrazin-1-yl­idene}meth­yl)phen­oxy]acetate

The complete molecule of the title compound, C22H24N2O6, is generated by crystallographic inversion symmetry and is approximately planar (r.m.s. deviation of the non-H atoms = 0.134 Å). The packing consists of inter-digitated sheets inclined at 25.9 (4)° to one another and linked by short C—H⋯O hydrogen bonds.

Crystal structure of ethyl 2-(2-{(1E)-[(E)-2-(2-hy­droxy­benzyl­idene)hydrazin-1-yl­idene]meth­yl}phen­oxy)acetate

In the title compound, C18H18N2O4, the planes of the benzene rings are twisted with respect to each other at 27.25 (7)°. The molecule displays an extended conformation with an intramolecular O—H⋯N hydrogen bond. In the crystal, weak C—H⋯O interactions link the molecules, forming supramolecular chains running along the b-axis direction.

Crystal structure of ethyl 4-(2-meth-oxy-phen-yl)-6-methyl-2-sulfanyl-idene-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

In the title compound, C15H18N2O3S, the hydropyrimidine ring adopts a sofa conformation with the methine C atom as the flap. The benzene ring is almost perpendicular to the mean plane of the hydropyrimidine ring, making a dihedral angle of 85.51 (8)°, and the methoxy O atom lies over the centre of the pyrimidine ring. In the crystal, weak N—H⋯S interactions form a zigzag chain running along the b-axis direction.

Crystal structure of (4Z)-4-[(di-methyl-amino)-methyl-idene]-3,5-dioxo-2-phenyl-pyrazolidine-1-carbaldehyde.

In the title compound, C13H13N3O3, the pyrazolidine ring adopts a shallow envelope conformation, with the carbonyl C atom closest to the benzene ring as the flap [deviation of 0.126 (1) Å from the plane through the remaining atoms (r.m.s. deviation = 0.011 Å)]. The dihedral angle between the pyrazolidine ring (all atoms) and the benzene ring is 51.09 (4)°. An extremely short (2.08 Å) intramolecular C—H⋯O contact is seen. In the crystal, molecules are linked by C—H⋯O bonds, generating [010] chains. Extremely weak C—H⋯π interactions are also observed.

Crystal structure of ethyl 2-({[(4Z)-3,5-dioxo-1-phenyl-pyrazolidin-4-yl-idene]meth-yl}amino)-acetate.

The title compound, C14H15N3O4, is nearly planar, the dihedral angle between the planes of the phenyl and pyrazolidine rings being 1.13 (7) Å, and that between the plane of the pyrazolidine ring and the mean plane of the side chain [C—N—C–C(=O)—O; r.m.s. deviation = 0.024 Å] being 2.52 (7)°. This is due in large part to the presence of the intramolecular N—H⋯O and C—H⋯O hydrogen bonds. In the crystal, pairwise N—H⋯O hydrogen bonds form inversion dimers, which are further associated into layers, lying very close to plane (-120), via pairwise C—H⋯O hydrogen bonds. The layers are then weakly connected through C—H⋯O hydrogen bonds, forming a three-dimensional structure.

3-Oxo-N′,2-diphenyl-2,3-di­hydro-1H-pyrazole-4-carbohydrazide

In the title compound, C16H14N4O2, the pyrazole ring makes a dihedral angle of 10.49 (8)° with its N-bound phenyl group, while it is nearly perpendicular to the other phenyl ring [dihedral angle = 88.47 (5)°]. The molecular conformation is stabilized by intramolecular C—H⋯O and N—H⋯O hydrogen bonds. In the crystal, the packing involves sheets of molecules parallel to (100) linked by N—H⋯O hydrogen bonds. A C—H⋯O interaction is also observed.