(E)-N′-(4-Isopropyl­benzyl­idene)isonicotinohydrazide monohydrate

In the title compound, C₁₆H₁₇N₃O·H₂O, the isonicotinohydrazide mol­ecule adopts an E conformation about the central C=N double bond. The dihedral angle between the pyridine and the benzene rings is 54.56 (15)°. In the crystal, mol­ecules are connected via N—H...O, O—H...N and O—H...O hydrogen bonds, forming a three-dimensional network.

(E)-2-(2,3-Dimethyl­anilino)-N′-[2-methyl-5-(prop-1-en-2-yl)cyclo­hex-2-enyl­idene]benzohydrazide

The asymmetric unit of the title compound, C₂₅H₂₉N₃O, comprises two crystallographically independent mol­ecules. The dihedral angles between the benzene rings in the two mol­ecules are 59.7 (2) and 61.27 (18)°. The cyclo­hexene rings adopt sofa and half-chair conformations. In the crystal, mol­ecules are connected via N—H...O and weak C—H...O hydrogen bonds, forming chains along the a axis. In each mol­ecule, there is an intra­molecular N—H...O hydrogen bond.

N′-[(1E,2E)-3,7-Dimethyl­octa-2,6-dien-1-yl­idene]pyridine-4-carbohydrazide

In the title compound, C₁₆H₂₁N₃O, the mol­ecule adopts an E conformation about the central C=N double bond. The 2-methyl­pent-2-ene group is disordered over two sets of sites, with a refined occupancy ratio of 0.785 (8):0.215 (8). The dihedral angle between the essentially planar [the r.m.s. value for the major component is 0.021 (7) and its maximum deviation is 0.025 (4) Å; the r.m.s. value for the minor component is 0.03 (4) and its maximum deviation is 0.05 (3) Å] major and minor components of the 2-methyl­but-2-ene group is 35.9 (13)°. In the crystal, C—H...O and N—H...O hydrogen bonds link the molecules, with the same O atom acting as the acceptor. This results in C¹₁(4) and C¹₁(5) [001] chains.

(Z)-7-[2-(4-Bromo­phen­yl)hydrazin-1-yl­idene]-6-methyl-3-(pyridin-4-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thia­diazine

In the asymmetric unit of the title compound, C₁₆H₁₂BrN₇S, there are two crystallographically independent mol­ecules with similar conformations. Both mol­ecules are slightly twisted; the central 1,2,4-triazolo[3,4-b]-1,3,4-thia­diazine ring system makes dihedral angles of 9.65 (15) and 13.29 (15)° with the pyridine and benzene rings, respectively, in one mol­ecule, whereas the corresponding values in the other mol­ecule are 9.30 (15) and 4.84 (15)°. A weak intra­molecular C—H...N inter­action with an S(6) ring motif is observed in each mol­ecule. In the crystal, the independent mol­ecules are each linked through N—H...N hydrogen bonds and weak C—H...N interactions into ribbons along the c axis. The ribbons are further linked together by weak C—H...N, C—H...π and π–π [centroid–centroid distances = 3.572 (2)–3.884 (2) Å] inter­actions.

(E)-2-(2,3-Dimethyl­anilino)-N′-(thio­phen-2-yl­methyl­idene)benzohydrazide

In the title compound, C₂₀H₁₉N₃OS, the central benzene ring makes dihedral angles of 45.36 (9) and 55.33 (9)° with the thio­phene ring and the dimethyl-substituted benzene ring, respectively. The dihedral angle between the thio­phene ring and dimethyl-substituted benzene ring is 83.60 (9)°. The thio­phene ring and the benzene ring are twisted from the mean plane of the C(=O)—N—N=C bridge [maximum deviation = 0.0860 (13) Å], with dihedral angles of 23.86 (9) and 24.77 (8)°, respectively. An intra­molecular N—H...O hydrogen bond generates an S(6) ring. In the crystal, mol­ecules are linked by N—H...O and C—H...O hydrogen bonds to the same acceptor atom, forming sheets lying parallel to the bc plane. The crystal packing also features C—H...π inter­actions.