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1.  N-(2-Carb­oxy­eth­yl)-2,5-dide­oxy-2,5-imino-d-mannonic acid [(3R,4R,5R)-1-(2-carb­oxy­eth­yl)-3,4-dihy­droxy-5-hy­droxy­methyl-l-proline] 
The absolute stereochemistry of the title compound, C9H15NO7, was determined from the use of d-glucuronolactone as the starting material. The compound crystallizes as the zwitterion. The five-membered ring adopts an envelope conformation with the –CH2OH-substituted C atom forming the flap. An intramolecular N—H⋯O hydrogen-bond occurs. In the crystal, the compound exists as a three-dimensional O—H⋯O intermolecular hydrogen-bonded network with each mol­ecule acting as a donor and acceptor for four hydrogen bonds.
doi:10.1107/S1600536812037488
PMCID: PMC3470222  PMID: 23125666
2.  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
3.  2,9-Dimethyl-1,10-phenanthrolin-1-ium (6-carb­oxy-4-hy­droxy­pyridine-2-carboxyl­ato-κ3 O 2,N,O 6)(4-hy­droxy­pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)zincate(II) 2.35-hydrate: a proton-transfer compound 
In the title compound, (C14H13N2)[Zn(C7H3NO5)(C7H4NO5)]·2.35H2O, the ZnII atom is coordinated by two N atoms and four O atoms from the carboxyl­ate groups of the 4-hy­droxy­pyridine-2,6-dicarboxyl­ate and 6-carb­oxy-4-hy­droxy­pyridine-2-carboxyl­ate ligands, forming a distored octa­hedral geometry. In the anion, the two pyridine rings are inclined to one another by 87.75 (13)°. Two types of robust O—H⋯O hydrogen bond synthons, viz. R 2 2(16) and R 6 6(42), link the anions to form a two-dimensional network parallel to the bc plane. Furthermore, O—H⋯O, N—H⋯O, N—H⋯N and weak C—H⋯O hydrogen bonds connect the two dimensional networks, forming a three-dimensional structure. In the crystal, there are also C—H⋯π and π–π inter­actions [centroid–centroid distances of 3.5554 (18) and 3.7681 (18) Å], and C=O⋯π inter­actions [O⋯centroid distance = 3.117 (2) Å] present. One of the three crystal water molecules shows an occupancy of 0.35.
doi:10.1107/S1600536811052445
PMCID: PMC3254305  PMID: 22259335
4.  Diaqua­(5-carb­oxy­benzene-1,3-dicarboxyl­ato-κO 1)[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ato-κ2 O 5,O 6]zinc monohydrate 
In the title compound, [Zn(C14H17N5O3)(C9H4O6)(H2O)2]·H2O, the complex mol­ecule exists in a zwitterionic form. The ZnII ion exhibits a distorted tetra­gonal-pyramidal geometry, being coordinated by two O atoms from the zwitterionic 8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ate (L) ligand, one O atom from the 5-carb­oxy­benzene-1,3-dicarboxyl­ate dianion, [Hbtc]2−, and two O atoms from two aqua ligands. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the components into a three-dimensional structure. The crystal packing exhibits π–π inter­actions between the aromatic rings, with centroid–centroid distances in the range 3.466 (3)–3.667 (3) Å.
doi:10.1107/S1600536813002122
PMCID: PMC3569215  PMID: 23424417
5.  2,9-Dimethyl-1,10-phenanthrolin-1-ium (6-carb­oxy-4-hy­droxy­pyridine-2-carboxyl­ato-κ3 O 2,N,O 6)(4-hy­droxy­pyridine-2,6-dicarboxyl­ato-κ3 O 2,N,O 6)nickelate(II) 2.35-hydrate: a proton-transfer compound 
The title proton-transfer compound, (C14H13N2)[Ni(C7H3NO5)(C7H4NO5)]·2.35H2O, consists of an [Ni(hypydc)(hypydcH)]− anion, a dmpH+ cation and 2.35 uncoordinated water mol­ecules (where hypydcH2 = 4-hy­droxy­pyridine-2,6-dicarb­oxy­lic acid and dmp = 2,9-dimethyl-1,10-phenanthroline). The NiII atom is coordinated by two N atoms and four O atoms from the carboxyl­ate groups of the (hypydc)2− and (hypydcH)− ligands, forming a distorted octa­hedral environment. In the anion, the two pyridine rings are inclined to one another by 89.24 (10)°. In the crystal, cations are linked via O—H⋯O hydrogen bonds forming dimers, graph-set [R 2 2(16)], centered about inversion centers. These dimers are further linked by other cation O—H⋯O hydrogen bonds, graph-set [R 6 6(42)], forming a two-dimensional network in (011). Additional inter­molecular O—H⋯O, N—H⋯O, N—H⋯N, and weak C—H⋯O hydrogen bonds, and π–π inter­actions [shortest centroid–centroid distance = 3.5442 (14) Å], connect the two dimensional networks, forming a three-dimensional arrangement. The H atoms of one of the methyl groups are disordered over two sites with equal occupancy.
doi:10.1107/S1600536810031399
PMCID: PMC3008066  PMID: 21588502
6.  2-N-Benzyl-2,6-dide­oxy-2,6-imino-3,4-O-iso­propyl­idene-d-allono­nitrile 
X-ray crystallography firmly established the relative stereochemistry of the title compound, C16H20N2O3. The acetonide ring adopts an envelope conformation with one of the O atoms as the flap and the piperidine ring adopts a slightly twisted boat conformation. The absolute configuration was determined by use of d-ribose as the starting material. The compound exists as O—H⋯O hydrogen-bonded chains of mol­ecules running parallel to the b axis.
doi:10.1107/S1600536813030584
PMCID: PMC3885044  PMID: 24454220
7.  N-Benzyl-1,3-dide­oxy-1,3-imino-l-xylitol 
The structure determination confirms the stereochemistry of the title compound, C12H17NO3, which contains a four-membered azetidine ring system. The absolute configuration was determined by the use of d-glucose as the starting material. In the crystal, O—H⋯O and O—H⋯N hydrogen bonds link the mol­ecules into layers in the ab plane.
doi:10.1107/S160053681103399X
PMCID: PMC3200798  PMID: 22059020
8.  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
9.  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
10.  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
11.  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
12.  Bis(μ-pyridinium-2-carboxyl­ato-κ2 O:O′)bis­[triaqua­(sulfato-κO)manganese(II)] 
The asymmetric unit of the title compound, [Mn2(SO4)2(C6H5NO2)2(H2O)6], comprises half of a centrosymmetric dimer. The MnII atom is coordinated by two O atoms of the monodentate carboxyl­ate ligand, an O atom of the sulfate anion in axial position and three water mol­ecules in a distorted octa­hedral geometry. In the crystal, mol­ecules are connected through N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional network. The crystal structure is further stabilized by inter­molecular π–π inter­actions [centroid–centroid distance = 3.842 (2) Å].
doi:10.1107/S1600536811054596
PMCID: PMC3254347  PMID: 22259381
13.  Diaqua­bis­{5-carb­oxy-2-[(1H-1,2,4-triazol-1-yl)meth­yl]-1H-imidazole-4-carboxyl­ato}zinc 
In the title compound, [Zn(C8H6N5O4)2(H2O)2], the six-coordinate ZnII ion, which is located on an inversion center, has a distorted octa­hedral configuration. Each 5-carb­oxy-2-[(1H-1,2,4-triazol-1-yl)meth­yl]-1H-imidazole-4-carboxyl­ate ligand chelates to the ZnII ion through a triazole N atom and a carboxyl­ate O atom in the equatorial plane. The coordination sphere is completed by two water mol­ecules in axial positions. There is an intra­molecular O—H⋯O hydrogen bond in the ligand. In the crystal, mol­ecules are linked via inter­molecular O—H⋯O, O—H⋯N and N—H⋯N hydrogen bonds, forming a three-dimensional structure.
doi:10.1107/S160053681104387X
PMCID: PMC3238584  PMID: 22199475
14.  Diaqua­bis­(4-carb­oxy-2-propyl-1H-imidazole-5-carboxyl­ato-κ2 N 3,O 4)zinc(II) N,N-dimethyl­formamide disolvate 
In the crystal structure of the title compound, [Zn(C8H9N2O4)2(H2O)2]·2C3H7NO, the ZnII atom is coordinated by two N,O-bidentate 2-propyl-1H-imidazole-4,5-dicarboxyl­ate anions and two water mol­ecules in a distorted octa­hedral environment. The asymmetric unit consists of one ZnII atom located on a center of inversion as well as one anion, one water mol­ecule and one additional dimethyl­formamide mol­ecule that occupy general positions. Between the carboxyl and the carboxyl­ate group an intra­molecular hydrogen bond is found in which the hydroxy H atom is disordered. Disorder is also found for the H atoms of one of the three methyl groups. In the crystal structure, additional inter­molecular N—H⋯O and O—H⋯O hydrogen bonding is found.
doi:10.1107/S1600536810022282
PMCID: PMC3006990  PMID: 21587728
15.  Diaqua­bis­(4-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ato-κ2 N 3,O 4)cadmium dihydrate 
The asymmetric unit of the title compound, [Cd(C7H7N2O4)2(H2O)2]·2H2O, consists of one CdII ion, one 4-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ate anion, one coordinated water mol­ecule and one lattice water mol­ecule. The CdII ion lies on a twofold axis, and is hexa­coordinated by four O atoms from water mol­ecules and carboxyl­ate groups and two N atoms from two imidazole rings, in a distorted octa­hedral arrangement. An extensive framework of N—H⋯O and O—H⋯O hydrogen bonds with the participation of coordinated and free water mol­ecules is found in the crystal structure, which contributes to the formation of a three-dimensional structure.
doi:10.1107/S1600536811021428
PMCID: PMC3151988  PMID: 21836881
16.  Disorder in the anionic part of catena-poly[[(pyrazine-2-carboxyl­ato)copper(II)]-μ-pyrazine-2-carboxyl­ato] 
The title compound, [Cu(C5H3N2O2)0.88(C6H4NO2)1.12]n, is characterized by disorder of the anion, resulting from a statistical occupation in a 0.44 (3):0.56 (3) ratio of pyrazine-2-carboxylate and pyridine-2-carboxylate. The compound was isolated during attempts to synthesize a mixed-ligand coordination polymer by solvothermal reaction between copper(II) nitrate and equimolar mixtures of pyrazine-2-carboxylic acid and pyridine-2-carb­oxy­lic acid in a mixture of water and EtOH. The difference in the two components of the compound is due to substitutional disorder of a CH group for one of the N atoms of the pyrazine ring which share the same site in the structure. In the crystal structure, the CuII atom lies on an inversion centre and is six-coordinated in a distorted N2O4 geometry. The carboxyl­ate group carbonyl O atoms are weakly coordinated to an equivalent CuII atom that is translated one unit cell in the a-axis direction, thus forming a polymeric chain through carboxyl­ate bridges.
doi:10.1107/S1600536812012378
PMCID: PMC3343884  PMID: 22589852
17.  Diaqua­bis­(5-carb­oxy-2-ethyl-1H-imidazole-4-carboxyl­ato-κ2 N 3,O 4)cobalt(II) trihydrate 
In the title compound, [Co(C7H7N2O4)2(H2O)2]·3H2O, the CoII cation, located on an inversion center, is N,O-chelated by two 5-carboxy-2-ethyl-1H-imidazole-4-carboxylate anions and further coordinated by two water mol­ecules in a distorted octa­hedral geometry. Only one carboxy group of the anion is deprotonated, and the two carboxyl groups of the same anion are linked via an intra­molecular O—H⋯O hydrogen bond. One of the lattice water mol­ecules is located on an inversion center, its H atom equally disordered over two positions. One of H atoms of another lattice water mol­ecules is also equally disordered over two sites. Water H atoms and the amino H atom all are involved in an inter­molecular hydrogen-bonded network in the crystal.
doi:10.1107/S1600536812008902
PMCID: PMC3343793  PMID: 22589767
18.  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
19.  Diaqua­bis­(4-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ato-κ2 N 3,O 4)zinc N,N-dimethyl­formamide disolvate 
In the title compound, [Zn(C7H7N2O4)2(H2O)2]·2C3H7NO, the ZnII ion, which lies on a center of inversion, is coordinated by two O atoms and two N atoms from two 4-carboxy-2-ethyl-1H-imid­azole-5-carboxyl­ato anions and two water O atoms in an octa­hedral environment, Each 4-carboxy-2-ethyl-1H-imid­azole-5-carboxyl­ato ligand adopts a bidentate chelating mode to the ZnII ion, forming two five-membered metalla rings. In the crystal, a two-dimensional framework parallel to (010) is formed by N—H⋯O and O—H⋯O hydrogen bonds.
doi:10.1107/S1600536811012992
PMCID: PMC3089267  PMID: 21754307
20.  Diaqua­bis­(5-carb­oxy-1H-imidazole-4-carboxyl­ato-κ2 N 3,O 4)iron(II) 
In the title compound, [Fe(C5H3N2O4)2(H2O)2], the FeII ion lies on an inversion centre and is coordinated by two N and two O atoms from two 5-carb­oxy-1H-imidazole-4-carboxyl­ate ligands and two water mol­ecules in a distorted octa­hedral geometry. An intra­molecular O—H⋯O hydrogen bond occurs. In the crystal, inter­molecular N—H⋯O and O—H⋯O hydrogen bonds form a three-dimensional network, which consolidates the packing.
doi:10.1107/S1600536811024779
PMCID: PMC3151786  PMID: 21836968
21.  Bis(μ-2-phenyl­quinoline-4-carboxyl­ato)bis­[aqua­(1,10-phenanthroline)(2-phenyl­quinoline-4-carboxyl­ato)manganese(II)] dihydrate 
In the centrosymmetric dinuclear title complex, [Mn2(C16H10NO2)4(C12H8N2)2(H2O)2]·2H2O, the MnII cation is in a distorted octa­hedral coordination geometry defined by two N atoms from a 1,10-phenanthroline ligand, one water O atom and three O atoms from three 2-phenyl­quinoline-4-carboxyl­ate anions. A pair of 2-phenyl­quinoline-4-carboxyl­ate anions bridge two Mn cations, forming the dinuclear mol­ecule. An intra­moleculr O—H⋯O hydrogen bond occurs. Inter­molecular O—H⋯O and O—H⋯N hydrogen bonds are present in the crystal structure.
doi:10.1107/S1600536811039341
PMCID: PMC3201393  PMID: 22065024
22.  3-(4-Carb­oxy-5-carboxyl­ato-1H-imidazol-2-yl)pyridin-1-ium monohydrate 
In the zwitterionic mol­ecule of the title compound, C10H7N3O4·H2O, one carboxyl group is deprotonated and the pyridine N atom is protonated. The pyridinium and imidazole rings form a dihedral angle of 5.23 (1)°. An intramolecular O—H⋯O hydrogen bond occurs. In the crystal, inter­molecular N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the zwitterions and water mol­ecules into sheets parallel to (102).
doi:10.1107/S1600536811002248
PMCID: PMC3051609  PMID: 21523144
23.  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
24.  (2,2′-Bipyridine-6,6′-dicarboxyl­ato-κ3 N,N′,O 6)(6′-carb­oxy-2,2′-bipyridine-6-carboxyl­ato-κ3 N,N′,O 6)cobalt(III) 
The CoIII atom in the title compound, [Co(C12H6N2O4)(C12H7N2O4)], is six-coordinated in a distorted octa­hedral geometry by four N atoms and two O atoms of the chelating 2,2′-bipyridine-6,6′-dicarboxyl­ate and 6′-carb­oxy-2,2′-bipyridine-6-carboxyl­ate ligands. Intermolecular O—H⋯O hydrogen bonds and face-to-face π-stacking inter­actions [centroid–centroid distance = 3.6352 (16) Å] between inversion-related pyridine rings link adjacent mononuclear units into a two-dimensional supra­molecular structure, and several inter­molecular C—H⋯O inter­actions are also observed.
doi:10.1107/S1600536812009816
PMCID: PMC3343819  PMID: 22589793
25.  3,5-Diamino-4H-1,2,4-triazol-1-ium (6-carb­oxy­pyridine-2-carboxyl­ato)(pyridine-2,6-dicarboxyl­ato)cuprate(II) trihydrate 
In the complex anion of the title compound, (C2H6N5)[Cu(C7H4NO4)(C7H3NO4)]·3H2O, the CuII atom is coordinated by tridentate 6-carb­oxy­pyridine-2-carboxyl­ate and pyridine-2,6-dicarboxyl­ate ligands and is surrounded by four O atoms in the equatorial plane and two N atoms in axial positions in a distorted octa­hedral geometry. In the crystal, the components are linked into a three dimensional network by O—H⋯O, N—H⋯O, N—H⋯N and C—H⋯O hydrogen bonds and a π–π inter­action with a centroid–centroid distance of 3.6080 (8) Å.
doi:10.1107/S1600536811011147
PMCID: PMC3099907  PMID: 21754014

Results 1-25 (137350)