Fadila Berrah

2-Amino-3-carb-oxy-pyrazin-1-ium nitrate monohydrate.

In crystal structure of the title compound, C5H6N3O2 +·NO3 −·H2O, intermolecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the cations, anions and water molecules into ribbons extending in [10]. Weak intermolecular C—H⋯O hydrogen bonds further link these ribbons into sheets parallel to ( 3).

Bis(3-amino­pyrazine-2-carboxyl­ato-κ2N1,O)di­aqua­nickel(II) dihydrate

In the title compound, [Ni(C5H4N3O2)2(H2O)2]·2H2O, the NiII ion lies on an inversion center and is coordinated in an slightly distorted octahedral environment by two N,O-chelating 3-aminopyrazine-2-carboxylate (APZC) ligands in the equatorial plane and two trans-axial aqua ligands. In the crystal, O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds involving the solvent water molecules, aqua and APZC ligands form layers parallel to (010). These layers are linked further via O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds involving the axial aqua ligands, amino groups and the carboxylate groups of the APZC ligands, forming a three-dimensional network.

Bis(2-amino-3-carb­oxy­pyrazin-1-ium) sulfate dihydrate

The crystal structure of the title compound, 2C5H6N3O2 +·SO4 2−·2H2O, displays a variety of N—H⋯O and O—H⋯O hydrogen bonds in which all potential donors and acceptors are involved. In the crystal, cations and anions are interconnected, forming R 3 3(10) and R 2 2(8) ring motifs whereas the anions and water molecules form R 2 3(10) rings, which develop in chains running along [100]. The resulting three-dimensional network exhibits undulating sheets parallel to (011), marked by the presence of R 6 6(26) rings in which six cations are involved.

Bis(5-amino-3-carb-oxy-1H-1,2,4-triazol-4-ium) sulfate dihydrate.

The crystal structure of the title compound, 2C3H5N4O2 +·SO4 2−·2H2O, displays a three-dimensional framework in which mixed infinite chains [oriented parallel to (510) and (10)] interfere, forming tunnels extending parallel to the c axis. Intermolecular O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds ensure the unity of the structure and generate centrosymmetric R 4 4(14) and R 4 2(8) rings. The S atom lies on a twofold axis.

Bis(2-amino-3-carb-oxy-pyridinium) sulfate trihydrate.

In the title compound, 2C6H7N2O2 +·SO4 2−·3H2O, there are two independent cations which are connected into N—H⋯O hydrogen-bonded dimers. In the crystal, O—H⋯O hydrogen-bonded sulfate–water sheets run parallel to (001) and are linked into a three-dimensional network via intermolecular N—H⋯O and O—H⋯O hydrogen bonds through the 2-aminonicotinium dimers. Further stabilization is provided by weak intermolecular C—H⋯O hydrogen bonds. R 4 3(10) and R 2 2(8) graph-set rings are observed. The crystal studied was an inversion twin with refined components of 0.45 (6) and 0.55 (6).

Bis(3-amino-pyrazine-2-carboxyl-ato-κ(2)N(1),O)diaqua-cobalt(II).

In the title compound, [Co(C5H4N3O2)2(H2O)2], the CoII atom is situated on a twofold rotation axis and is N,O-chelated by two 3-aminopyrazine-2-carboxylate anions and additionally bonded to the O atoms of two water molecules, leading to a slightly distorted octahedral coordination environment. The crystal packing is dominated by intermolecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonding involving the water molecules and amino groups as donors and carboxylate O atoms, as well as the non-coordinating heterocyclic N atoms as acceptors, resulting in a three-dimensional network. An intramolecular N—H⋯O hydrogen bond is also observed.

5-Amino-3-carb­oxy-1H-1,2,4-triazol-4-ium nitrate monohydrate

The two-dimensional crystal packing of the title compound, C(3)H(5)N(4)O(2) (+)·NO(2) (-)·H(2)O, results from the stacking of well separated layers (i.e. with nothing between the layers) parallel to the (-113) plane in which adjacent cations adopt a head-to-head arrangement such that two -COOH groups are linked via two water mol-ecules (the water O atom behaves simultaneously as donor and acceptor of hydrogen bonds) and two -NH(2) groups are linked through two nitrate anions. This arrangement leads to alternating hydro-philic and hydro-phobic zones in which O-H⋯O and N-H⋯O hydrogen bonds, respectively, are observed.

2-Amino-3-carb­oxy­pyridinium nitrate

In the crystal structure of the title compound, C6H7N2O2 +·NO3 −, the cations are linked via C—H⋯O hydrogen bonds, forming infinite chains running along the b axis. These chains are further linked through N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds to the nitrate anions, forming well-separated infinite planar layers parallel to (001).

2-Amino-3-carb­oxy­pyridinium chloride hemihydrate

The asymmetric unit of the title compound, C6H7N2O2 +·Cl−·0.5H2O, consists of two protonated 2-amino-3-carboxypyridine cations, two chloride anions and one molecule of water. The crystal packing can be described as alternating layers of cations and anions parallel to (110), which are linked together by Ow—H⋯Cl interactions. In the crystal, four types of classical hydrogen bonds are observed, viz. cation–anion (O—H⋯Cl and N—H⋯Cl), cation–cation (N—H⋯O), cation–water (N—H⋯Ow) and water–anion (Ow—H⋯Cl), resulting in the formation of an infinite three-dimensional network.

2-Amino-3-carb­oxy­pyridinium perchlorate

The asymmetric unit includes two crystallographically independent equivalents of the title salt, C6H7N2O2 +·ClO4 −. The cations and anions form separate layers alternating along the c axis, which are linked by N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds into a two-dimensional network parallel to (100). Further C—H⋯O contacts connect these layers, forming a three-dimensional network, in which R 4 4(20) rings and C 2 2(11) infinite chains can be identified.