4-Cyano­pyridinium bromide

In the title compound, C6H5N2 +·Br−, the pyridine N atom is protonated and involved in an inter­molecular N—H⋯Br hydrogen bond which, together with weak C—H⋯N hydrogen bonds, results in the formation of a chain along the c axis. Weak inter­molecular C—H⋯Br inter­actions between pyridine H atoms and Br− anions connect these chains into a network parallel to the bc plane

Oxalic acid–pyridine-4-carbonitrile (1/2)

In the title compound, 2C6H4N2·C2H2O4, the oxalic acid mol­ecule lies about an inversion center. The pyridine ring of the pyridine-4-carbonitrile mol­ecule is almost planar, the largest deviation from the least-squares plane being 0.006 (1) Å; the nitrile N atom deviates from this plane by 0.114 (1) Å. In the crystal, the oxalic acid mol­ecules and the pyridine-4-carbonitrile mol­ecules form stacks. Neighboring mol­ecules within the stacks are related by translation in the a direction, with inter­planar distances of 3.183 (1) and 3.331 (2) Å, respectively. Each oxalic acid mol­ecule forms strong O—H⋯N hydrogen bonds with two mol­ecules of pyridine-4-carbonitrile. Besides this, there are also weak C—H⋯O inter­actions

1,1′-(Phenyl­methyl­ene)dinaphthalen-2-ol

In the title compound, C27H20O2, the phenyl ring is oriented with respect to the naphthalene ring systems at 57.87 (6) and 85.12 (6)°. The two naphthalene ring systems make a dihedral angle of 70.10 (4)°. In the mol­ecule, the hy­droxy groups are involved in a strong intra­molecular O—H⋯O hydrogen bond. In the crystal, inversion dimers linked by pairs of O—H⋯O hydrogen bonds occur. A weak C—H⋯π inter­action is also observed in the crystal

4-Cyano­pyridinium chloride

In the crystal structure of the title salt, C6H5N2 +·Cl−, the pyridinium cation links to the Cl− anion via an N—H⋯Cl hydrogen bond. Weak C—H⋯Cl inter­actions also occur

4-Cyano­pyridinium nitrate

The title compound, C6H5N2 +·NO3 −, is a proton-transfer compound between 4-cyano­pyridine and nitric acid. In the asymmetric unit, the components are linked by a strong N—H⋯O hydrogen bond. In the crystal, mol­ecules are linked into a C(6) chain along [010] by C—H⋯O inter­actions

Adamantane-1-ammonium benzoate

In the title molecular salt, C10H15NH3 +·C7H5O2 −, both carboxyl O atoms act as acceptors for strong N—H⋯O inter­molecular hydrogen-bond inter­actions with the ammonium group in the cation, generating infinite chains along the b axis. A weak C—H⋯π inter­action is also present

Methyl isonicotinate 1-oxide

In the title compound, C7H7NO3, the benzene ring and the methyl ester group are nearly coplanar, forming a dihedral of 3.09 (9)°. The crystal structure is stabilized by inter­molecular C—H⋯O hydrogen bonds, forming layers parallel to (101)

1,4-Diazo­niabicyclo­[2.2.2]octane hexa­aqua­magnesium bis­(sulfate)

In the title compound, (C6H14N2)[Mg(H2O)6](SO4)2, the MgII ion, lying on an inversion center, is coordinated by six water mol­ecules in a slightly distorted octa­hedral geometry. The 1,4-diazo­niabicyclo­[2.2.2]octane cation is located about a twofold rotation axis. Inter­molecular N—H⋯O and O—H⋯O hydrogen bonds link the cations and the anions into a three-dimensional network

2-(2H-Tetra­zol-5-yl)pyridinium perchlorate monohydrate

In the cation of the title compound, C6H6N5 +·ClO4 −·H2O, the pyridinium and tetra­zole rings are essentially coplanar, making a dihedral angle of 1.2 (2)°. In the crystal, inter­molecular N—H⋯O and O—H⋯O hydrogen bonds link the cations, anions and water mol­ecules into a ribbon-like structure along the c axis. Adjacent ribbons are linked via π–π stacking inter­actions between the tetra­zole rings, with a centroid–centroid distance of 3.484 (2) Å