Bis(dicyclo-hexyl-aminium) 2-carb-oxy-methyl-2-hy-droxy-succinate ethanol monosolvate.

In the title compound, 2C(12)H(24)N(+)·C(6)H(6)O(7) (2-)·C(2)H(6)O, the cyclo-hexane rings of the cations adopt chair conformations. In the anion, intra-molecular O-H⋯O hydrogen bonds occur. In the crystal, the cations link with the anions via N-H⋯O hydrogen bonds.

2,3-Diamino-pyridinium 6-carb-oxy-pyridine-2-carboxyl-ate.

The asymmetric unit of the title proton-transfer compound, C(5)H(8)N(3) (+)·C(7)H(4)NO(4) (-), consists of one mono-deprotonated pyridine-2,6-dicarb-oxy-lic acid as anion and one protonated 2,3-diamino-pyridine as cation. The crystal packing shows extensive O-H⋯O, N-H⋯O and N-H⋯N hydrogen bonds. Thre are also several π-π inter-actions between the anions and also between the cations [centriod-centroid distances = 3.

Propane-1,2-diaminium bis-(pyridine-2,6-dicarboxyl-ato-κO,N,O)cuprate(II) tetra-hydrate.

In the title compound, (C(3)H(12)N(2))[Cu(C(7)H(3)NO(4))(2)]·4H(2)O, the Cu(II) atom is six-coordinated in a distorted octa-hedral geometry by two tridentate pyridine-2,6-dicarboxyl-ate (pydc) ligands. In the crystal, inter-molecular O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds, as well as π-π stacking inter-actions between the pyridine rings of the pydc ligands [centroid-centroid distance = 3.4714 (14) Å] are present.

Propane-1,2-diaminium bis-(pyridine-2,6-dicarboxyl-ato-κO,N,O)cadmate dihydrate.

The reaction of cadmium nitrate dihydrate, propane-1,2-diamine and pyridine-2,6-dicarb-oxy-lic acid in a 1:1:2 molar ratio in an aqueous solution resulted in the formation of the title compound, (C(3)H(12)N(2))[Cd(C(7)H(3)NO(4))(2)]·2H(2)O or (p-1,2-daH(2))-[Cd(pydc)(2)]·2H(2)O (where p-1,2-da is propane-1,2-diamine and pydcH(2) is pyridine-2,6-dicarb-oxy-lic acid). The Cd(II) ion is coordinated by four O and two N atoms of two pydc ligands in a distorted octa-hedral environment. The structure also contains two uncoordinated water mol-ecules.

Bis(8-hy-droxy-2-methyl-quinolinium) bis-(pyridine-2,6-dicarboxyl-ato)-nickelate(II) methanol monosolvate monohydrate.

In the title compound, (C(10)H(10)NO)(2)[Ni(C(7)H(3)NO(4))(2)]·CH(3)OH·H(2)O, the coordination geometry of the Ni(II) atom can be described as distorted octa-hedral. In the crystal, noncovalent inter-actions play an important role in the stabilization of the structure, involving O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds and π-π stacking inter-actions between the pyridine rings of the pyridine-2,6-dicarboxyl-ate ligands [centroid-centroid distance = 3.7138 (15) Å] and between the 8-hy-droxy-2-methyl-quinolinium cations [centroid-centroid distances = 3.

Poly[tri-μ(2)-aqua-(μ(3)-pyridine-2,4-dicarboxyl-ato-κN,O:O:O)barium].

In the polymeric title compound, [Ba(C(7)H(3)NO(4))(H(2)O)(3)](n), the Ba(II) ion is ten-coordinated in an NO(9) environment by one N atom and three O atoms from three pyridine-2,4-dicarboxyl-ate (pydc) ligands and six water mol-ecules. The μ(3)-pydc ligands and the bridging water mol-ecules connect the Ba atoms into a layer parallel to (100). The crystal packing is stabilized by O-H⋯O and C-H⋯O hydrogen bonds.

Propane-1,2-diaminium tris-(pyridine-2,6-dicarboxyl-ato-κO,N,O)zirconate(IV) trihydrate.

In the title compound, (C(3)H(12)N(2))[Zr(C(7)H(3)NO(4))(3)]·3H(2)O, the Zr(IV) cation is chelated by three pyridine-2,6-dicarboxyl-ate anions in a distorted tricapped trigonal-prismatic environment. The crystal structure is stabilized by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds.

N,N-Dimethyl-propane-1,2-diaminium bis-(6-carb-oxy-pyridine-2-carboxyl-ate) monohydrate.

The asymmetric unit of the title proton-transfer compound, C(5)H(16)N(2) (2+)·2C(7)H(4)NO(4) (-)·H(2)O, consists of two mono-deproton-ated pyridine-2,6-dicarb-oxy-lic acid mol-ecules as anions, viz. (py-2,6-dcH)(-), one diprotonated N(1),N(1)-dimethyl-propane-1,2-diamine mol-ecule as a cation, viz. (dmpdaH(2))(2+), and one water mol-ecule.

Benzene-1,3-diammonium bis-(pyridine-2,6-dicarboxyl-ato-κO,N,O)cobaltate(II) penta-hydrate.

In the title compound, (C(6)H(10)N(2))[Co(C(7)H(3)NO(4))(2)]·5H(2)O, the Co(II) ion is six-coordinated in an N(2)O(4) environment by two pyridine-2,6-dicarboxyl-ate (pydc) ligands, having a distorted octa-hedral geometry. The crystal packing is stabilized by inter-molecular N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds. There are also π-π inter-actions between the pyridine rings of the pydc ligands and between the pydc ligands and the benzene-1,3-diammonium cations, with centroid-centroid distances of 3.

Bis(1-methyl-4-oxoimidazolidin-2-iminium) diaqua-bis-(pyridine-2,4-dicarboxyl-ato-κN,O)zincate(II) dihydrate.

In the title compound, (C(4)H(8)N(3)O)(2)[Zn(C(7)H(3)NO(4))(2)(H(2)O)(2)]·2H(2)O, the Zn(II) ion is six-coordinated in a distorted octa-hedral geometry by two pyridine-2,4-dicarboxyl-ate (pydc) ligands in the equatorial plane and two water mol-ecules in the axial positions. The pydc ligands act as bidentate chelating ligands through one carboxyl-ate O atom and the pyridine N atom. Inter-molecular N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds stabilize the crystal structure.

2,2'-Azanediyl-diethanaminium pyridine-2,5-dicarboxyl-ate.

The crystal structure of the title compound, C(4)H(15)N(3) (2+)·C(7)H(3)NO(4) (2-), consists of diethyl-enetriaminium (2,2'-azanediyl-diethanaminium) cations and pyridine-2,5-dicarboxyl-ate anions, which are linked by N-H⋯O, N-H⋯N and C-H⋯O hydrogen bonds. C-H⋯π inter-actions are also observed. In the anion, the carboxyl-ate groups are oriented at dihedral angles of 11.

Bis(4-carb-oxy-pyridine-2-carboxyl-ato-κN,O)copper(II) dimethyl sulfoxide disolvate.

In the title complex, [Cu(C(7)H(4)NO(4))(2)]·2C(2)H(6)OS, the Cu(II) atom is situated on an inversion centre and is N,O-chelated by two monoanionic 4-carb-oxy-pyridine-2-carboxyl-ate ligands in a slightly distorted square-planar coordination geometry. The dimethyl sulfoxide solvent mol-ecules and Cu(II) complex mol-ecules are linked by O-H⋯O hydrogen bonding. In addition, C-H⋯O contacts and π-π inter-actions [centroid-centroid distance = 3.

(2,2'-Bipyridine)(pyridine-2,6-dicarboxyl-ato)oxidovanadium(IV) ethanol monosolvate.

In the title compound, [V(C(7)H(3)NO(4))O(C(10)H(8)N(2))]·C(2)H(5)OH, the V(IV) atom exhibits a distorted octa-hedral coordination environment formed by two pyridyl N atoms of 2,2'-bipyridine (bpy), the vanadyl O atom, and two carboxyl-ate O atoms and one pyridyl N atom of the tridentate pyridine-2,6-dicarboxyl-ate (pydc(2-)) ligand. The pyridyl N atom of the pydc(2-) anion and one pyridyl N atom of bpy occupy the axial positions. O-H⋯O hydrogen bonds involving the ethanol solvent mol-ecule as donor and a carboxyl-ate O atom as acceptor atoms, as well as C-H⋯O hydrogen bonds, together with π-π stacking inter-actions between adjacent aromatic rings (average centroid-centroid distance = 3.

Poly[aqua-(dimethyl sulfoxide)(μ(4)-pyridine-2,5-dicarboxyl-ato)calcium(II)].

In the polymeric title compound, [Ca(C(7)H(3)NO(4))(H(2)O)(C(2)H(6)OS)](n), the Ca(II) ion is coordinated in a distorted penta-gonal-bipyramidal CdNO(6) geometry. The crystal packing is stabilized by O-H⋯O hydrogen bonds and π-π stacking inter-actions between the aromatic rings of pyridine-2,5-dicarb-oxy-late with centroid-centroid distances of 3.6166 (13) Å.

Benzene-1,3-diammonium bis-(pyridine-2,6-dicarboxyl-ato)nickelate(II) penta-hydrate.

In the title compound, (C(6)H(10)N(2))[Ni(C(7)H(3)NO(4))(2)]·5H(2)O, the Ni(II) ion is six-coordinated by two N and four O atoms from two pyridine-2,6-dicarboxyl-ate ligands in a distorted octa-hedral fashion. The crystal packing is stabilized by inter-molecular O-H⋯O and N-H⋯O and weak C-H⋯O hydrogen bonds and π-π inter-actions [centroid-centroid distances = 3.4669 (19) and 3.

Bis(2-amino-4-methyl-pyridinium) bis-(pyridine-2,6-dicarboxyl-ato)cuprate(II).

The asymmetric unit of the title compound, (C(6)H(9)N(2))(2)[Cu(C(7)H(3)NO(4))(2)], contains half of a [Cu(pydc)(2)](2-) (pydcH(2) is pyridine-2,6-dicarb-oxy-lic acid) anion and one protonated 2-amino-4-methyl-pyridine (2a4mpH)(+) counter-ion. The anion is a six-coordinated complex with a distorted CuN(2)O(4) octa-hedral geometry around the Cu(II) ion. N-H⋯O and C-H⋯O hydrogen bonds along with π-π contacts between the pyridine rings of the (2a4mpH)(+) cations [centroid-centroid distance = 3.

Propane-1,3-diaminium pyridine-2,5-di-carboxyl-ate dimethyl sulfoxide mono-solvate.

In the crystal structure of the title solvated molecular salt, C(3)H(12)N(2) (2+)·C(7)H(3)NO(4) (2-)·C(2)H(6)OS, two amine groups of propane-1,3-diamine (pda) are protonated and two carb-oxy-lic acid groups of pyridine-2,5-dicarb-oxy-lic acid (2,5-pydcH(2)) are deprotonated. The crystal packing features N-H⋯O hydrogen bonds and weak C-H⋯O inter-molecular inter-actions.

Bis(8-hy-droxy-2-methyl-quinolinium) bis-(pyridine-2,6-dicarboxyl-ato)cuprate(II) methanol monosolvate monohydrate.

The title compound, (C(10)H(10)NO)(2)[Cu(C(7)H(3)NO(4))(2)]·CH(3)OH·H(2)O was prepared by the reaction of copper(II) nitrate hexa-hydrate, 8-hy-droxy-2-methyl-quinoline, and pyridine-2,6-dicarb-oxy-lic acid in a 1:2:2 molar ratio in an aqueous solution. The geometry of the resulting CuN(2)O(4) coordination can be described as distorted octa-hedral. In the crystal, there are several inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds.

Bis(2,3-diamino-pyridinium) bis-(μ-pyridine-2,6-dicarboxyl-ato)-κO,N,O:O;κO:O,N,O-bis-[aqua-(pyridine-2,6-dicarboxyl-ato-κO,N,O)bis-muthate(III)] tetra-hydrate.

In the centrosymmetric dinuclear complex anion of the title compound, (C(5)H(8)N(3))(2)[Bi(2)(C(7)H(3)NO(4))(4)(H(2)O)(2)]·4H(2)O, the Bi(III) atom is eight-coordinated in an N(2)O(6) environment and has a distorted bicapped trigonal-prismatic coordination environment. Extensive inter-molecular O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds lead to the stability of the crystal structure. Inter-actions between one C-H group of the 2,3-diamino-pyridinium [(2,3-dapyH)(+)] cation and the aromatic ring of the pyridine-2,6-dicarboxyl-ate (pydc) ligand (C-H⋯centroid distance = 2.

catena-Poly[[[(2,2'-bipyridine-κN,N')(dimethyl sulfoxide-κO)(nitrato-κO,O')bis-muth(III)]-μ-5-carb-oxy-benzene-1,3-dicarboxyl-ato-κO,O:O,O] dimethyl sulfoxide monosolvate].

The polymeric title compound, {[Bi(C(9)H(4)O(6))(NO(3))(C(10)H(8)N(2))(C(2)H(6)OS)]·C(2)H(6)OS}(n), was obtained by the reaction of bis-muth(III) nitrate, bipyridine (bpy) and 1,3,5-benzene-tricarb-oxy-lic acid (H(3)BTC). The Bi(III) ion is coordinated in a distorted tricapped trigonal-prismatic geometry, defined by two N atoms of the bipy ligand, four O atoms of two HBTC(2-) anions, two O atoms of a nitrate anion and one O atom of a dimethyl sulfoxide ligand. The crystal packing is stabilized by O-H⋯O and C-H⋯O hydrogen bonds.

catena-Poly[4,4'-bipyridinium [[tetra-aqua-(pyridine-2,6-dicarboxyl-ato-κO,N,O)cerate(III)]-μ-pyridine-2,6-dicarboxyl-ato-κO:O,N,O-[(pyridine-2,6-dicarboxyl-ato-κO,N,O)cerate(III)]-μ-pyridine-2,6-dicarboxyl-ato-κO,N,O:O] penta-hydrate].

The title compound, {(C(10)H(10)N(2))[Ce(2)(C(7)H(3)NO(4))(4)(H(2)O)(4)]·5H(2)O}(n), is composed of a one-dimensional anionic complex, a doubly protonated 4,4'-bipyridine mol-ecule as a counter-ion and five uncoordinated water mol-ecules. The anion bears two nine-coordinate Ce(III) ions, each with a distorted tricapped trigonal-prismatic geometry. In the crystal, inter-molecular C-H⋯O, N-H⋯O and O-H⋯O hydrogen bonds, as well as π-π inter-actions with centroid-centroid distances of 3.

Bis(2-amino-6-methyl-pyridinium) tris-(pyridine-2,6-dicarboxyl-ato)zirconate(IV) dihydrate.

In the title compound, (C(6)H(9)N(2))(2)[Zr(C(7)H(3)NO(4))(3)]·2H(2)O, the Zr(IV) atom is nine-coordinated by three pyridine-2,6-dicarboxyl-ate ligands in a distorted tricapped trigonal-prismatic ZrN(3)O(6) environment. The crystal packing is stabilized by inter-molecular N-H⋯O and O-H⋯O hydrogen bonds.

2-Amino-4-methyl-pyridinium 6-carb-oxy-pyridine-2-carboxyl-ate sesquihydrate.

In the title compound, C(6)H(9)N(2) (+)·C(7)H(4)NO(4) (-)·1.5H(2)O, extensive O-H⋯O, O-H⋯N, N-H⋯O and C-H⋯O hydrogen bonds, as well as ion pairing, π-π stacking inter-actions [centroid-centroid distances = 3.4690 (8) and 3.

Bis(propane-1,2-diammonium) benzene-1,2,4,5-tetra-carboxyl-ate dihydrate.

In the crystal of the title hydrated molecular salt, 2C(3)H(12)N(2) (2+)·C(10)H(2)O(8) (4-)·2H(2)O, the packing is stabilized by extensive N-H⋯O and O-H⋯O hydrogen-bonding inter-actions involving all three species, forming a supra-molecular three-dimensional structure. The tetraanion is generated by inversion.

Hexaaqua-magnesium(II) bis-(pyridinium-2,6-dicarboxyl-ate).

In the title compound, [Mg(H(2)O)(6)](C(7)H(4)NO(4))(2), a single six-coordinate Mg(2+) cation (site symmetry 2/m) is bonded to six water mol-ecules in a distorted octa-hedral geometry. The crystal packing between the complex cation and the zwitterionic organic cation (m symmetry) is stabilized by inter-molecular O-H⋯O hydrogen bonds and weak inter-molecular C-H⋯O inter-actions.