(E)-Ethyl N′-(3-hy­droxy­benzyl­idene)hydrazinecarboxyl­ate dihydrate

The asymmetric unit of the title compound, C10H12N2O3·2H2O, contains two organic mol­ecules with similar conformations and four water mol­ecules. Each organic mol­ecule is close to planar (r.m.s. deviations = 0.035 and 0.108 Å) and adopts a trans conformation with respect to its C=N bond. In the crystal, the components are linked into a three-dimensional network by N—H⋯O, O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds, some of which are bifurcated. An R 2 2(8) loop occurs between adjacent organic mol­ecules

(E)-Methyl N′-[(1H-indol-3-yl)methyl­idene]hydrazinecarboxyl­ate 0.25-hydrate

The asymmetric unit of the title compound, C11H11N3O2·0.25H2O, contains two independent organic mol­ecules and a water mol­ecule, which lies on a twofold rotation axis. The side chains of the two mol­ecules have slightly different orientations, the C=N—N—C torsion angle being −163.03 (15)° in one and −177.52 (14)° in the other, with each adopting a trans configuration with respect to the C=N bond. In the crystal, mol­ecules are linked into chains extending along b by N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds and in addition, four inter­molecular C—H⋯π inter­actions are present

N′-(4-Hydr­oxy-3-methoxy­benzyl­idene)acetohydrazide monohydrate

In the title compound, C10H12N2O3·H2O, the Schiff base mol­ecule is approximately planar [within 0.189 (1) Å]. The inter­planar angle between the benzene and acetohydrazide planes is 8.50 (10)°. In the crystal, mol­ecules are linked into a three-dimensional network by strong and weak O—H⋯O and strong N—H⋯O hydrogen bonds. The hydr­oxy H atom deviates from the 4-hydr­oxy-3-methoxy­phenyl mean plane by 0.319 (2) Å, probably due to the involvement of this H atom in the O—H⋯O hydrogen bond. The weak O—H⋯O hydrogen bond is involved in a bifurcated hydrogen bond with R 1 2(4) motif. A weak C—H⋯π inter­action is also present

N′-(3,4-Dihydroxy­benzyl­idene)acetohydrazide

In the title compound, C9H10N2O3, the Schiff base mol­ecule is approximately planar, the dihedral angle between the benzene ring and the acetohydrazide group (r.m.s. deviation = 0.034 Å) being 8.81 (7)°. An intra­molecular O—H⋯O hydrogen bond is observed. In the crystal, mol­ecules are linked into a three-dimensional network by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds

(Methoxy­carbon­yl)hydrazinium chloride monohydrate

In the title compound, C2H7N2O2 +·Cl−·H2O, the non-H atoms of the cation are approximately coplanar. The organic cations, chloride ions and water mol­ecules are linked into a two-dimensional network parallel to the bc plane by N—H⋯O, N—H⋯Cl and O—H⋯Cl hydrogen bonds

N′-(4-Hydroxy­benzyl­idene)aceto­hydrazide monohydrate

In the title compound, C9H10N2O2·H2O, the mol­ecular skeleton of the acetohydrazide mol­ecule is nearly planar [within 0.014 (1) Å]. The mol­ecule adopts a trans configuration with respect to the C=N bond, while the side chain is slightly twisted away from the attached ring, forming a dihedral angle of 9.975 (8)°. The crystal packing exhibits a three-dimensional network composed from alternating acetohydrazide mol­ecules and uncoordinated water mol­ecules, which inter­act via N—H⋯O, O—H⋯O and O—H⋯N hydrogen bonds. A C—H⋯π inter­action is also present

(E)-Methyl N′-(3-methoxy­benzyl­idene)hydrazinecarboxyl­ate

The title compound, C10H12N2O3, crystallizes with two independent mol­ecules in the asymmetric unit which differ in the orientation of the meth­oxy group. Each independent mol­ecule adopts a trans configuration with respect to the C=N bond. In the crystal structure, mol­ecules are linked into chains running along [001] by N—H⋯O and N—H⋯N hydrogen bonds. In addition, an inter­molecular C—H⋯π inter­action is observed

(E)-Methyl N′-(2-furylmethyl­ene)­hydrazinecarboxyl­ate

The title compound, C7H8N2O3, crystallizes with two independent but essentially identical mol­ecules in the asymmetric unit. Each mol­ecule adopts a trans configuration with respect to the C=N bond. The hydrazinecarboxyl­ate group is twisted from the furan ring by 7.78 (13)° in one mol­ecule and by 7.01 (17)° in the other. In the crystal structure, mol­ecules are linked into chains running along [010] by bifurcated N—H⋯(N,O) and N—H⋯O hydrogen bonds. In addition, weak C—H⋯O inter­actions and an O⋯C short contact [2.896 (3) Å] are observed

(E)-Methyl N′-[1-(4-methoxy­phen­yl)ethyl­idene]hydrazinecarboxyl­ate

The mol­ecule of the title compound, C11H14N2O3, adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the hydrazinecarboxyl­ate plane is 12.06 (9)°. Mol­ecules are linked into a one-dimensional network by N—H⋯O hydrogen bonds and C—H⋯π inter­actions. The benzene rings of inversion-related mol­ecules are stacked with their centroids separated by 3.777 (1) Å, indicating π–π inter­actions