Poly[aqua­(μ-pyrazine-2-carboxyl­ato-κ3 N,O:O)(μ-pyrazine-2-carboxyl­ato-κ3 N,O:O′)lead(II)]

The polymeric structure of the title compound, [Pb(C5H3N2O2)2(H2O)]n, is built up from centrosymmetric [Pb(C5H3N2O2)2(H2O)]2 dimers, which are bridged by ligand carboxyl­ate O atoms. The PbII ion adopts an irregular PbN2O5 coordination polyhedron; it is chelated by one N,O-bidentate ligand and also bonds to a water O atom. A second N,O-bidentate ligand forms the dimer bridge and another bridging O atom from a nearby dimer also bonds to the PbII ion, leading to layers propagating in (100). A network of O—H⋯O hydrogen bonds operates between water O atoms (donors) and carboxyl­ate O atoms (acceptors)

Poly[di-μ-aqua-μ4-(pyrazine-2,5-dicarboxyl­ato)-dilithium(I)]

In the title coordination polymer, [Li2(C6H2N2O2)(H2O)2]n the pyrazine-2,5-dicarboxyl­ate dianionic ligand bridges two symmetry-independent Li+ ions using both its N,O-chelating sites. The carboxyl­ate O atom of one of them also bridges to another Li+ ion, while the second O atom of this group is bonded to another Li+ ion. Two symmetry-independent water O atoms participate also in the bridging system, which gives rise to a polymeric three-dimensional framework. Both Li+ ions show distorted trigonal–bipyramidal LiNO4 coordination geometries, with the N atom in an axial site in both cases. The packing is consolidated by O—H⋯O hydrogen bonds, which occur between water mol­ecules as donors and carboxyl­ate O atoms as acceptors

catena-Poly[[(diaqua­zinc)-μ-3-carb­oxy­pyrazine-2-carboxyl­ato-κ4 N 1,O 2;N 4,O 3] nitrate]

The crystal structure of the title compound, {[Zn(C6H3N2O4)(H2O)2]NO3}n, is built of zigzag cationic chains propagating in [010] with nitrate anions located in the space between the chains. The ZnII ion is coordinated by N and O atoms of two symmetry-related ligands in equatorial sites, and by two water O atoms at the axial sites of a distorted octa­hedron. One carboxyl­ate group of the ligand remains protonated, serving as a donor in a short intra­molecular O—H⋯O hydrogen bond. The coordinated water mol­ecules are donors and the nitrate O atoms act as acceptors in a network of O—H⋯O hydrogen bonds

catena-Poly[[(6-carb­oxy­pyrazine-2-carboxyl­ato)lithium]-μ-aqua]

The asymmetric unit of the title compound, [Li(C6H3N2O4)(H2O)]n, contains an LiI ion with a distorted trigonal–bipyramidal coordination environment. It is chelated by a singly protonated ligand mol­ecule via its heterocyclic N atom, by two O aoms, each donated by an adjacent carboxyl­ate group, and is further coordinated by a water O atom which acts as a bridge, forming a mol­ecular ribbon. A proton attached to one of the carboxyl­ate O atoms is situated on an inversion centre and forms a short centrosymmetric hydrogen bond, generating mol­ecular layers parallel to the ac plane. These layers are held together by weak O—H⋯O hydrogen bonds in which the coordinated water mol­ecules act as donors, whereas carboxyl­ate O atoms are acceptors

Tetraaqua(pyrimidine-4,6-dicarboxylato-κ2N1,O6)magnesium monohydrate

In the title compound, [Mg(C6H2N2O4)(H2O)4]·H2O, the MgII ion is coordinated by a fully deprotonated pyrimidine-4,6-dicarboxylate molecule, via a ring N and a carboxylate O atom, and by four water O atoms at the apices of a slightly distorted octahedron. In the crystal, molecules are linked by O—H...O and O—H...N hydrogen bonds, forming a three-dimensional network