(E)-tert-Butyl 4-(N′-hy­droxy­carbam­­imid­o­yl)piperazine-1-carboxyl­ate

In the title compound, C₁₀H₂₀N₄O₃, the piperazine ring adopts a chair conformation. The mol­ecule adopts an E conformation across the C=N double bond, with the –OH group and the piperazine ring trans to one another. Further, the H atom of the hy­droxy group is directed away from the NH₂ group. An intra­molecular N—H...O contact occurs involving the NH₂ group and the oxime O atom. In the crystal, mol­ecules are linked via strong N—H...O and O—H...N hydrogen bonds with alternating R₂²(6) and C(9) motifs into tetra­meric units forming R₄⁴(28) motifs.

6-[4-Chloro-2-(trifluoro­meth­yl)phen­yl]-3-fluoro-2-methyl­pyridine

In the title compound, C₁₃H₈ClF₄N, the dihedral angle between the benzene and pyridine rings is 59.8 (3)°. In the crystal, mol­ecules are stacked in columns along the b axis through weak C—H...π inter­actions.

1-(2-Amino-6-methyl­pyrimidin-4-yl)-N,N-dimethyl­piperidin-4-aminium chloride

In the title mol­ecular salt, C₁₂H₂₂N₅⁺·Cl⁻, the cation is protonated at the dimethyl-substituted tertiary N atom. The piperidine ring adopts a chair conformation with the exocyclic N—C bond in an equatorial orientation. The dihedral angle between the piperidine ring (all atoms) and the pyrimidine ring is 14.00 (1)°. In the crystal, the ions are connected by N—H...N hydrogen bonds, forming inversion dimers, which are further connected by N—H...Cl hydrogen bonds. Aromatic π–π stacking inter­actions [centroid–centroid separation = 3.4790 (9) Å] are also observed in the structure.

Methyl 4-benz­yloxy-2-hy­droxy­benzoate

In the title compound, C₁₅H₁₄O₄, the dihedral angle between the benzene rings is 67.18 (8)°. The C_a—C_m—O—C_a (a = aromatic and m = methyl­ene) torsion angle is 172.6 (3)° and an intra­molecular O—H...O hydrogen bond generates an S(6) ring. In the crystal, mol­ecules are linked by C—H...O hydrogen bonds into zigzag chains propagating in [001] and C—H...π inter­actions also occur.

(E)-3-Chloro-N′-hy­droxy­benzene-1-carboximidamide

The title compound, C₇H₇ClN₂O, crystallizes with two independent mol­ecules in the asymmetric unit. The compound adopts an E configuration across the C=N double bond, as the –OH group and the benzene ring are on opposite sides of the double bond while the H atom of the hy­droxy group is directed away from the –NH₂ group. In the crystal, mol­ecules are linked to one another through O—H...N and N—H...O hydrogen bonds, forming chains along [010].

4-Methyl-2,6-bis­(pyrrolidin-1-yl)pyrimidine

In the crystal of the title compound, C₁₃H₂₀N₄, the mol­ecule is nearly planar, the dihedral angles between the pyrimidine and the two pyrrolidine rings being 4.71 (2) and 4.50 (2)°. The crystal features inversion-related dimers linked by pairs of C—H...N hydrogen bonds generating R₂²(16) patterns. The dimeric units are further linked into C(6) chains via an additional C—H...N hydrogen bond.

4-Nitro­phenyl 4-hy­droxy-3-methyl­benzoate

The asymmetric unit of the title compound, C₁₄H₁₁NO₅, contains two independent mol­ecules in which the dihedral angles between the benzene rings are 89.27 (16) and 77.14 (12)°. In the crystal, mol­ecules are linked by O—H...O hydrogen bonds, generating C(8) chains propagating in [010] for one mol­ecule and [001] C(8) chains for the other. The chains are connected by C—H...O hydrogen bonds and π–π inter­actions [shortest centroid–centroid distance = 3.5908 (12)°], generating a three-dimensional network.