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1.  catena-Poly[[[bis­(3-amino­pyrazine-2-carboxyl­ato)triaqua­praseodymium(III)]-μ-3-amino­pyrazine-2-carboxyl­ato-[(3-amino­pyrazine-2-carboxyl­ato)diaqua­formatopraseodymium(III)]-μ-3-amino­pyrazine-2-carboxyl­ato] hexa­hydrate] 
The asymmetric unit of the polymeric title compound, {[Pr2(C5H4N3O2)5(CHO2)(H2O)5]·6H2O}n, has two independent PrIII atoms; one is coordinated by two water mol­ecules and the other by three water mol­ecules. The first is N,O-chelated by three 3-amino­pyrazine-2-carboxyl­ate ions, whereas the second is chelated by two carboxyl­ate ions; both exist in a monocapped square-anti­prismatic geometry. The polymeric chains that run along the a axis inter­act with the lattice water mol­ecules, generating a three-dimensional hydrogen-bonded network. The formate ion is disordered over two positions with respect to the non-coordinated atoms in a 1:1 ratio.
doi:10.1107/S1600536811031308
PMCID: PMC3200950  PMID: 22065704
2.  Bis­(μ-pyridine-2,3-dicarboxyl­ato)bis­[aqua­(3-carb­oxy­pyridine-2-carboxyl­ato)indium(III)] tetra­hydrate 
In the binuclear centrosymmetric title compound, [In2(C7H3NO4)2(C7H4NO4)2(H2O)2]·4H2O, which contains both pyridine-2,3-dicarboxyl­ate and 3-carb­oxy­pyridine-2-carboxyl­ate ligands, the InIII atom is six-coordinated in a distorted octa­hedral geometry. One pyridine ligand is N,O-chelated while the other is N,O-chelated and at the same time bridging to the other via the second carboxyl group. In the crystal, an extensive O—H⋯O hydrogen-bonding network, involving the coordinated and lattice water mol­ecules and the carboxyl groups of the ligands, together with C—H⋯O and π–π inter­actions [centroid–centroid distance = 3.793 (1) Å], leads to the formation of a three-dimensional structure.
doi:10.1107/S1600536811053566
PMCID: PMC3254334  PMID: 22259367
3.  Di-μ-aqua-bis­(μ-pyridazine-4-carboxyl­ato-κ2 N:N′)bis­[triaqua­(pyridazine-4-carboxyl­ato-κ2 O,O′)lead(II)] dihydrate 
The structure of the title compound, [Pb2(C5H3N2O2)4(H2O)6]·2H2O, is composed of dimeric mol­ecules in which two symmetry-related Pb2+ ions are bridged by a pair of two pyridazine-4-carboxyl­ate ligand mol­ecules via both heterocyclic N atoms and two water O atoms. Each Pb2+ ion is also coordinated by two carboxyl­ate O atoms and three water O atoms, leading to a highly irregular coordination polyhedron around Pb2+. The dimers are inter­connected by hydrogen bonds between coordinated and uncoordinated water mol­ecules and the carboxyl­ate O atoms. O—H⋯N inter­actions are also present.
doi:10.1107/S1600536809039658
PMCID: PMC2971413  PMID: 21578059
4.  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.
doi:10.1107/S1600536811046198
PMCID: PMC3238630  PMID: 22199521
5.  catena-Poly[[(3,5-dicarb­oxy­pyrazine-2,6-dicarboxyl­ato-κ3 O 2,N 1,O 6)lithium(I)]-μ-aqua-[triaqua­lithium(I)]-μ-aqua] 
The title coordination polymer, [Li2(C8H2N2O8)(H2O)5]n contains two symmetry-independent Li+ ions; one is coordin­ated by five water O atoms, the other by an O,N,O′-tridentate doubly deprotonated pyrazine-2,3,5,6-tetra­carboxyl­ate ligand and two water O atoms. Water mol­ecules bridge adjacent Li+ ions into ribbons propagating in [100]; an alternative analysis of the structure considers it to contain alternating [Li(C8H2N2O8)(H2O)2]− anions and [Li(H2O)3]+ cations. In the polymeric model, both lithium ions show distorted trigonal–bipyramidal coordination geometries. Within the ligand, the carboxyl H atoms participate in short, almost symmetric O⋯H⋯O hydrogen bonds in which the non-coordinated carboxyl­ate O atoms are donors and acceptors. In the crystal, the ribbons inter­act via a network of O—H⋯O hydrogen bonds in which the coordinated water mol­ecules act as donors and ligand carboxyl­ate O atoms as acceptors.
doi:10.1107/S1600536810045903
PMCID: PMC3011810  PMID: 21589251
6.  catena-Poly[[(5-carb­oxy-2H-1,2,3-triazole-4-carboxyl­ato-κ2 N 3,O 4)sodium]-di-μ-aqua-κ4 O:O] 
In the title coordination polymer, [Na(C4H2N3O4)(H2O)2]n, the NaI atom is six-coordinated by one O atom and one N atom from a 2H-1,2,3-triazole-4-carb­oxy-5-carboxyl­ate ligand and four O atoms from four water mol­ecules, forming a distorted octa­hedal geometry. The NaI atoms are bridged by water mol­ecules into a chain structure along [100]. Inter­molecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds connect the chains. An intra­molecular O—H⋯O hydrogen bond between the carboxyl­ate groups is observed.
doi:10.1107/S1600536810037384
PMCID: PMC2983283  PMID: 21587466
7.  catena-Poly[[di­aqua­bis­(μ3-5-carboxyl­ato-1H-pyrazole-3-carb­oxy­lic acid-κ3 O 3:O 3;O 5)dilithium(I)] monohydrate] 
The basic structural unit of the title polymeric ribbon, {[Li2(C5H3N2O2)2(H2O)2]·H2O}n, is a centrosymmetric dinuclear complex in which the two LiI ions are bridged by two carboxyl­ato O atoms, to generate a centrosymmetric Li2O2 core. These are connected into a chain along [01-1] by carboxylic acid–carbonyl-O bonds. The tetra­hedral coordination of the LiI cation is completed by an aqua ligand. The carboxylic acid is involved in an intra-ribbon hydrogen bond. A solvate water molecule showing positional (50:50) disorder is observed. Polymeric ribbons along [01-1] are connected by O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds into a three-dimensional architecture.
doi:10.1107/S1600536813026408
PMCID: PMC3884253  PMID: 24454029
8.  catena-Poly[[[aqua­(5-carb­oxy­pyridine-3-carboxyl­ato-κN)copper(I)]-μ-4,4′-bipyridine-κ2 N:N′] monohydrate] 
In the title compound, {[Cu(C7H4NO4)(C10H8N2)(H2O)]·H2O}n, the CuI ion is coordinated by the N atom from a 5-carb­oxy­pyridine-3-carboxyl­ate anion, two N atoms from two 4,4′-bipyridine (4,4′-bipy) ligands and one water mol­ecule in a distorted tetra­hedral geometry. The 4,4′-bipy ligands bridge the CuI ions into polymeric chains propagating in [201]. The latticeand the coordinating water mol­ecules as well as the carboxy OH function are involved in the formation of inter­molecular O—H⋯O hydrogen bonds, which consolidate the crystal packing.
doi:10.1107/S1600536811055656
PMCID: PMC3274861  PMID: 22346808
9.  catena-Poly[[aqua­lithium(I)]-μ-3-carb­oxy-5,6-di­methyl­pyrazine-2-carboxyl­ato-κ4 O 2,N 1:O 3,N 4] 
The asymmetric unit of the title compound, [Li(C8H6N2O4)(H2O)]n, comprises three Li cations, two of which are located on a twofold rotation axis, two carboxylate anions and three water mol­ecules, of which two are situated on the twofold rotation axis being aqua ligands. Both carboxylate anions are in μ2-bridging mode. All Li ions show a trigonal–bipyramidal coordination mode; the two located in special positions are bridged through N,O-bonding sites generating a polymeric ribbon along the c-axis direction. The Li cation in a general position creates an independent polymeric ribbon through N,O-bonding sites of the two symmetry-related ligands; the trigonal–bipyramidal coordination is completed by an aqua ligand. In both carboxylate anions, a carboxyl­ate and a carb­oxy­lic acid group form an intra­molecular hydrogen bond. The polymeric ribbons running along [001] are inter­connected by hydrogen bonds in which the water mol­ecules act as donors and carboxyl­ate O atoms act as acceptors, giving rise to a three-dimensional architecture.
doi:10.1107/S1600536813030493
PMCID: PMC3884992  PMID: 24454167
10.  catena-Poly[[[tetra­aqua­erbium(III)]-μ-oxalato-κ4 O 1,O 2:O 1′,O 2′] [bromidobis(pyrazine-2-carboxyl­ato-κ2 N 1,O)cuprate(II)] tetra­hydrate] 
In the title heterometallic complex, {[Er(C2O4)(H2O)4][CuBr(C5H3N2O2)2]·4H2O}n, the ErIII atom is eight-coordin­ated by four O atoms from two centrosymmetric oxalate ligands and four water mol­ecules, displaying a bicapped trigonal-prismatic geometry. The oxalate ligands bridge the Er atoms into a polymeric cationic chain along [110]. The CuII atom is five-coordinated in a square-pyramidal geometry by two pyrazine-2-carboxyl­ate ligands and a Br atom, forming a discrete anion. The polymeric cations, complex anions and uncoordinated water mol­ecules are self-assembled into a three-dimensional supra­molecular network through O—H⋯N, O—H⋯O and O—H⋯Br hydrogen bonds.
doi:10.1107/S1600536810025274
PMCID: PMC3007546  PMID: 21588122
11.  catena-Poly[[[(1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydro­quinoline-3-carboxyl­ato-κ2 O 3,O 4)copper(II)]-μ-1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydro­quinoline-3-carboxyl­ato-κ3 N 7′:O 3,O 4] tetra­hydrate] 
In the title compound, {[Cu(C16H17FN3O3)2]·4H2O}n, the CuII atom is bonded to two O,O′-bidentate 1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydro­quinoline-3-carboxyl­ate (norf) monoanions and a symmetry-generated N-bonded norf anion, resulting in a distorted square-pyramidal coordination environ­ment with the N atom occupying the apical site. The bridging norf anion results in one-dimensional chains propogating along [010]. A network of O—H⋯O and N—H⋯O hydrogen bonds helps to establish the crystal structure.
doi:10.1107/S1600536808026469
PMCID: PMC2960715  PMID: 21201639
12.  Penta­aqua­(5-carb­oxy­pyridine-2-carboxyl­ato-κ2 N,O 2)(pyridine-2,5-dicarboxyl­ato-κ2 N,O 2)cerium(III) tetra­hydrate 
In the title compound, [Ce(C7H3NO4)(C7H4NO4)(H2O)5]·4H2O, the Ce3+ ion is nine-coordinated by two O atoms and two N atoms from one single and from one double deprotonated pyridine-2,5-dicarboxyl­ate ligand and five water mol­ecules in a distorted monocapped square-anti­prismatic geometry. In the crystal, extensive O—H⋯O hydrogen-bonding inter­actions result in a three-dimensional supra­molecular architecture.
doi:10.1107/S1600536811052688
PMCID: PMC3254311  PMID: 22259342
13.  cis-Tri­aqua­[1,1′-(propane-1,3-di­yl)bis­(pyridin-1-ium-4-carboxyl­ato)-κO]bis­(thio­cyanato-κN)manganese(II) dihydrate 
In the title compound, [Mn(NCS)2(C15H14N2O4)(H2O)3]·2H2O, the metal ion is octa­hedrally coordinated by three water mol­ecules, one carboxyl­ate O atom from a 1,1′-(propane-1,3-di­yl)bis­(pyridinium-4-carboxyl­ate) ligand and two N atoms from two thio­cyanate anions in cis positions, forming a mononuclear complex mol­ecule. In the crystal, mol­ecules are connected into a three-dimensional architecture through O—H⋯O hydrogen bonds involving water mol­ecules and carboxyl­ate groups.
doi:10.1107/S1600536814000701
PMCID: PMC3998253  PMID: 24764814
14.  catena-Poly[[[triaqua­(nitrato-κ2 O,O′)neodymium(III)]-bis­(μ2-pyridinium-4-carboxyl­ato-κ2 O:O′)] bis­(perchlorate) monohydrate] 
In the title compound, {[Nd(NO3)(C6H5NO2)2(H2O)3](ClO4)2·H2O}n, the NdIII atom is nine-coordinated by four O atoms from four pyridinium-4-carboxyl­ate ligands, two O atoms from a chelating nitrate anion and three water mol­ecules in a distorted tricapped trigonal–prismatic coordination geometry. Adjacent Nd atoms are linked by the bidentate pyridinium-4-carboxyl­ate ligands into a chain running along the b axis. The chains are further connected by O—H⋯O and N—H⋯O hydrogen bonds into a three-dimensional network.
doi:10.1107/S1600536808043997
PMCID: PMC2968357  PMID: 21581760
15.  Tri­aqua­(pyrazole-4-carboxyl­ato-κN 1)lithium 
In the monomeric title complex, [Li(C4H3N2O2)(H2O)3], the Li+ cation is coordinated by a pyrazole N atom and three water mol­ecules in a distorted tetra­hedral geometry. The carboxyl­ate group is deprotonated. The complex mol­ecules are involved in O—H⋯O and N—H⋯O hydrogen bonding, forming layers stacked along the b axis.
doi:10.1107/S160053681301831X
PMCID: PMC3793681  PMID: 24109268
16.  Bis(6′-carb­oxy-2,2′-bipyridine-6-carboxyl­ato-κ3 N,N′,O 6)nickel(II) tetra­hydrate 
In the title compound, [Ni(C12H7N2O4)2]·4H2O, the Ni atom is located at the centre of a distorted octa­hedron, formed by four N atoms and two O atoms from the same two tridentating chelated 6-carb­oxy-2,2′-bipyridine-6′-carboxyl­ate (L) ligands. Face-to-face π-stacking inter­actions between inversion-related pyridine rings with centroid–centroid distances of 3.548 (3) and 3.662 (3) Å (perpendicular distances between the respective rings are 3.314 and 3.438 Å) are found. Inter­molecular O—H⋯O hydrogen bonds between water mol­ecules and L ligands form R 5 3(10), R 6 5(14) and R 5 5(12) rings and also a centrosymmetric cage-like unit of water mol­ecules, which link eight adjacent NiII centers, forming a three-dimensional framework.
doi:10.1107/S1600536809006515
PMCID: PMC2968579  PMID: 21582115
17.  Diaqua­bis­(5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ato-κ2 N 3,O 4)nickel(II) tetra­hydrate 
In the title complex, [Ni(C8H9N2O4)2(H2O)2]·4H2O, the NiII ion is coordinated in a slightly distorted octa­hedral environment formed by two bis-chelating H2pimda (H3pimda is 2-propyl-1H-4,5-dicarb­oxy­lic acid) ligands and two coordinated water mol­ecules. In the crystal structure, a three-dimensional framework is formed by inter­molecular O—H⋯O and N—H⋯O hydrogen bonds involving the solvent water mol­ecules, coordinated water mol­ecules, carboxyl­ate O atoms and the protonated N atoms of the H2pimda ligands. The propyl groups of each H2pimda ligand are disordered over two sets of sites with refined occupancies of 0.50 (2):0.50 (2) and 0.762 (11):0.238 (11). In one water solvent mol­ecule, one of the H atoms was refined as disordered over two sites of equal occupancy.
doi:10.1107/S1600536810025237
PMCID: PMC3007488  PMID: 21588141
18.  Di-μ-aqua-bis­[aqua­(5-carboxyl­ato-1H-1,2,3-triazole-4-carb­oxy­lic acid-κ2 N 3,O 4)lithium] 
The crystal structure of the title compound, [Li2(C4H2N3O4)2(H2O)4], contains centrosymmetric dinuclear mol­ecules in which two LiI ions are bridged by two water O atoms. The metal ion is coordinated by one N,O-bidentate ligand and three water O atoms (one of them is symmetry generated), with one of the bridging water O atoms in the apical position of a distorted square pyramid. The carboxyl­ate group that participates in coordination to the metal ion remains protonated; the other is deprotonated and coordination inactive. An intra­molecular O—H⋯O hydrogen bond between carboxyl­ate groups is observed. In the crystal, dimers are linked by O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds, generating a three-dimensional network.
doi:10.1107/S1600536813023167
PMCID: PMC3884415  PMID: 24427005
19.  catena-Poly[[diaqua­lithium]-μ-[rac-cis-(2-carb­oxy­cyclo­hexane-1-carboxyl­ato-κ2 O 1:O 2]] 
In the structure of the title compound, [Li(C8H11O4)(H2O)2]n, the distorted tetra­hadral LiO4 coordination sphere comprises two water mol­ecules and two carboxyl O-atom donors from separate bridging cis-2-carb­oxy­cyclo­hexane-1-carboxyl­ate monoanions [Li—O = 1.887 (4)–1.946 (3) Å], giving chain substructures which extend along [010]. Water–water and water–carboxyl O—H⋯O hydrogen bonds stabilize these chain structures and provide inter­chain links, resulting in a two-dimensional layered structure extending parallel to (100).
doi:10.1107/S1600536811045077
PMCID: PMC3238593  PMID: 22199484
20.  Poly[[μ2-aqua-μ3-(4-carb­oxy-2-propyl-1H-imidazole-5-carboxyl­ato-κ4 N 3,O 4:O 4:O 5)-sodium] hemihydrate] 
In the title compound, {[Na(C8H9N2O4)(H2O)]·0.5H2O}n, the Na+ ion is coordinated by two bridging water mol­ecules, one N atom and three O atoms from three 4-carb­oxy-2-propyl-1H-imidazole-5-carboxyl­ate (H2pimdc) ligands. Adjacent Na+ ions are linked alternately by two water O atoms and two carb­oxy O atoms into a chain along [001]. These chains are connected through the coordination of the carboxyl­ate O atoms to the Na+ ions, forming a three-dimensional structure. An intra­molecular O—H⋯O hydrogen bond and inter­molecular N—H⋯O and O—H⋯O hydrogen bonds are present in the crystal structure.
doi:10.1107/S1600536811007732
PMCID: PMC3099890  PMID: 21753940
21.  catena-Poly[[[bis­(3-hy­droxy­adamantane-1-carboxyl­ato-κO 1)(3-hy­droxy­adamantane-1-carb­oxy­lic acid-κO 1)zinc(II)]-μ2-4,4′-bipyridine] monohydrate] 
In the title coordination polymer, {[Zn(C11H15O3)2(C10H8N2)(C11H16O3)]·H2O}n, the ZnII ion is five coordinated by two N atoms from two 4,4′-bipyridine (4,4′-bpy) mol­ecules and three O atoms from two 3-hy­droxy­adamantane-1-carboxyl­ate anions (L) and one 3-hy­droxy­adamantane-1-carb­oxy­lic acid (HL) mol­ecule. The resulting coordination polyhedron is a near regular ZnN2O3 trigonal bipyramid, with the N atoms in axial sites. The 4,4′-bpy mol­ecules [dihedral angle between the aromatic rings = 17.2 (2)°] act as bridges, connecting the metal ions into an infinite polymeric chain propagating in [01]. O—H⋯O hydrogen bonds help to consolidate the packing.
doi:10.1107/S1600536811016424
PMCID: PMC3120402  PMID: 21754615
22.  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.
doi:10.1107/S1600536811054031
PMCID: PMC3254337  PMID: 22259370
23.  Tetra­aqua­bis­(6-chloro­pyridine-3-carboxyl­ato-κO)nickel(II) tetra­hydrate 
In the title compound, [Ni(C6H3ClNO2)2(H2O)4]·4H2O, the NiII ion is located on an inversion centre and is octa­hedrally coordinated by four O atoms from four water mol­ecules in the equatorial plane and two O atoms of two 6-chloro-3-carboxyl­ate ligands in axial positions. There are also four lattice water molecules present. The organic ligands are bound to the NiII ion in a monodentate manner through a carboxyl­ate O atom. There is one strong intra­molecular O—H⋯O hydrogen bond and six inter­molecular O—H⋯O and O—H⋯N hydrogen-bonding inter­actions in the packing, resulting in a complex three-dimensional network structure.
doi:10.1107/S160053681204322X
PMCID: PMC3515138  PMID: 23284365
24.  Guanidinium hexa­aqua­zinc(II) bis[tris­(3-carb­oxy­pyridine-2-carboxyl­ato)zincate] 
In the title mol­ecular salt, (CH6N3)1.30[Zn(H2O)6]0.35[Zn(C7H4NO4)3]2, the ZnII atom (site symmetry 3) in the anion is coordinated by three N,O-bidentate 3-carb­oxy­pyridine-2-carboxyl­ate monoanions to generate a fac-ZnN3O3 octa­hedral coordination geometry. The guanidinium cation (the C atom has site symmetry 3) and the octa­hedral hexa­aqua­zinc(II) dication (the Zn2+ cation has site symmetry -3) are occupationally disordered in a 1.30:0.35 ratio. In the crystal, the components are linked by O—H⋯O and N—H⋯O hydrogen bonds to generate infinite (001) sheets. Weak aromatic π–π stacking [centroid–centroid distance = 3.797 (8) Å] is also observed in the crystal.
doi:10.1107/S160053681202987X
PMCID: PMC3414107  PMID: 22904714
25.  Tetra­aqua­bis­(6-chloro­pyridine-3-carboxyl­ato-κO)cobalt(II) tetra­hydrate 
In the title compound, [Co(C6H3ClNO2)2(H2O)4]·4H2O, the CoII cation is located on an inversion center and is coordinated by four water mol­ecules and two 6-chloro­pyridine-3-carboxyl­ate anions in a slightly distorted octa­hedral geometry. In the crystal, complex mol­ecules and lattice water mol­ecules are linked by O—H⋯O and O—H⋯N hydrogen bonds into a three-dimensional network.
doi:10.1107/S160053681204319X
PMCID: PMC3515139  PMID: 23284366

Results 1-25 (36755)