4-Meth­oxy­benzamidinium acetate

The title compound, C₈H₁₁N₂O⁺·CH₃CO₂⁻, was synthesized by a reaction between 4-meth­oxy­benzamidine (4-amidino­anisole) and acetic acid. In the cation, the amidinium group forms a dihedral angle of 11.65 (17)° with the mean plane of the benzene ring. The ionic components are associated in the crystal via N—H⁺...O⁻ hydrogen bonds, resulting in a one-dimensional structure consisting of dimers and catemers and orientated approximately along the c axis.

4-Meth­oxy­benzamidinium nitrate

The title salt, C₈H₁₁N₂O⁺·NO₃⁻, was synthesized by a reaction between 4-meth­oxy­benzamidine (4-amidino­anisole) and nitric acid. The asymmetric unit comprises a non-planar 4-meth­oxy­benzamidinium cation and a nitrate anion. In the cation, the amidinium group has two similar C—N bond lengths [1.302 (3) and 1.313 (3) Å] and its plane forms a dihedral angle of 32.66 (5)° with the mean plane of the benzene ring. The nitrate–amidinium ion pair is not planar, as the dihedral angle between the planes defined by the CN₂⁺ and NO₃⁻ units is 19.28 (6)°. The ionic components are associated in the crystal via N—H...O hydrogen bonds, resulting in a three-dimensional network.

4-Meth­oxy­benzamidinium hydrogen oxalate monohydrate

The title hydrated salt, C₈H₁₁N₂O⁺·C₂HO₄⁻·H₂O, was synthesized by a reaction of 4-meth­oxy­benzamidine (4-amidino­anisole) and oxalic acid in water solution. In the cation, the amidinium group forms a dihedral angle of 15.60 (6)° with the mean plane of the benzene ring. In the crystal, each amidinium unit is bound to three acetate anions and one water mol­ecule by six distinct N—H...O hydrogen bonds. The ion pairs of the asymmetric unit are joined by two N—H...O hydrogen bonds into ionic dimers in which the carbonyl O atom of the semi-oxalate anion acts as a bifurcated acceptor, thus generating an R¹₂(6) motif. These subunits are then joined through the remaining N—H...O hydrogen bonds to adjacent semi-oxalate anions into linear tetra­meric chains running approximately along the b axis. The structure is stabilized by N—H...O and O—H...O inter­molecular hydrogen bonds. The water mol­ecule plays an important role in the cohesion and the stability of the crystal structure being involved in three hydrogen bonds connecting two semi-oxalate anions as donor and a benzamidinium cation as acceptor.