N′-(4-Hy­droxy­benzyl­idene)ferrocene-1-carbohydrazide

In the title compound, [Fe(C₅H₅)₂(C₁₃H₁₁N₂O₂)], the dihedral angle between the benzene ring and the cyclo­penta­diene ring bonded to the carbonyl group is 26.1 (2)°. In the crystal, bifurcated O—H...(O,N) and N—H...O hydrogen bonds link the mol­ecules into a three-dimensional network.

1-(2-Hy­droxy-3,5-dimeth­oxy­phen­yl)ethanone

In title compound, C₁₀H₁₂O₄, all of the non-H atoms lie approximately in a plane with the largest deviation being 0.061 (2) Å. An intra­molecular O—H...O hydrogen bond generates an S(6) ring motif. No classical inter­molecular hydrogen bonding occurs, with only van der Waals forces stabilizing the crystal structure.

3,3′-[Biphenyl-4,4′-diylbis(­oxy)]diphthalic acid

In the title mol­ecule, C₂₈H₁₈O₁₀, the two central benzene rings form a dihedral angle of 31.0 (1)°. In the phthalic acid fragments, the carb­oxy groups in the meta positions are approximately coplanar with the attached benzene rings, being inclined to their planes at 2.7 (1) and 10.3 (1)°, while the carb­oxy groups in the ortho positions are twisted from the benzene ring planes by 83.5 (1) and 75.4 (1)°. In the crystal, O—H...O hydrogen bonds link the mol­ecules into layers parallel to the bc plane. Weak C—H...O hydrogen bonds and π–π inter­actions between the aromatic rings [centroid–centroid distance = 3.7674 (3) Å] further consolidate the crystal packing.

2-(4-Carb­oxy­piperidinium-1-yl)pyridine-3-carboxyl­ate

The title compound, C₁₂H₁₄N₂O₄, crystallizes as a zwitterion. A negative charge is delocalized in the deprotonated carboxyl group attached to the pyridine ring. The piperidine N atom accepts a proton and the ring is transformed into a piperidinium cation. There is an intra­molecular N—H...O hydrogen bond between the protonated NH and a carboxyl­ate O atom. In the crystal, an O—H...O hydrogen bond between the carboxyl group and the carboxyl­ate O atom of another mol­ecule generates a helix along the b axis.

Bis{1-[(1H-benzotriazol-1-yl)meth­yl]-2-methyl-1H-imidazole-κN³}dichlorido­cobalt(II)

In the title mononuclear complex, [CoCl₂(C₁₁H₁₁N₅)₂], the Co^II atom is four-coordinated by two ligand N atoms and two Cl atoms in a distorted tetra­hedral geometry. In the crystal, mol­ecules are stacked through π–π inter­actions [centroid–centroid distances = 3.473 (2), 3.807 (3), 3.883 (2) and 3.676 (2) Å], forming a three-dimensional supra­molecular network.

catena-Poly[[diaqua­bis­[2-(3-oxo-1,3-di­hydro-2-benzofuran-1-yl)acetato-κO]cobalt(II)]-μ-1,2-bis­(pyridin-4-yl)ethane-κ²N:N′]

In the title complex, [Co(C₁₀H₇O₄)₂(C₁₂H₁₂N₂)(H₂O)₂]_n, the Co^II ion is located on a crystallographic centre of symmetry and is six-coordinated by two N atoms from two 1,2-bis­(4-pyrid­yl)ethane ligands, two carboxylate O atoms from two 1,3-dihydro-3-oxo-1-isobenzofuran­acetate ligands and two terminal water ligands. The 1,2-bis(4-pyrid­yl)ethane ligands act as bidentate ligands, and bridge the Co^II ions into infinite chains extending parallel to [010]. In these chains, there are intra-mol­ecular O—H...O hydrogen bonding between the coordination water mol­ecules and carboxyl­ate groups. Inter-mol­ecular O—H...O hydrogen bonding between the adjacent chains and π...π stacking inter­actions result in the formation of a three-dimensional supra­molecular network.

5-(4-Methyl­phen­yl)-1,3,4-oxadiazol-2-amine

In the crystal structure of the title compound, C₉H₉N₃O, adjacent mol­ecules are linked through N—H...N hydrogen bonds into a three-dimensional network.