Three methoxy‐substituted diethyl 4‐­phenyl‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate compounds

Diethyl 4‐(2,5‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₁H₂₇NO₆, (I), diethyl 4‐(3,4‐di­methoxy­phenyl)‐2,6‐di­methyl‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₁H₂₇NO₆, (II), and diethyl 2,6‐di­methyl‐4‐(3,4,5‐tri­methoxy­phenyl)‐1,4‐di­hydro­pyridine‐3,5‐di­carboxyl­ate, C₂₂H₂₉NO₇, (III), crystallize with hydrogen‐bonding networks involving the H atom bonded to the N atom of the 1,4‐di­hydro­pyridine ring and carbonyl O atoms in (I) and (II). Unusually, (III) shows O atoms of methoxy groups serving as hydrogen‐bond acceptors.     

An indium(III)–water chain based on an unusual acyclic water pentamer

An in situ reaction under hydro­thermal conditions leads to the formation of the title compound, diaqua­(pyridine‐2‐carboxyl­ato)­(pyridine‐2,6‐dicarboxyl­ato)indium(II) trihydrate, [In(C₆H₄NO₂)(C₇H₃NO₄)(H₂O)₂]·3H₂O, in which the central In^III atom is seven‐coordinated by one pyridine‐2,6‐di­carboxyl­ate ligand, one pyridine‐2‐carboxyl­ate ligand and two water mol­ecules in a penta­gonal–bipyramidal coordination environment. An indium(III)–water chain based on an unusual water pentamer is observed.     

Bis(μ‐pyridine‐2,6‐carboxyl­ato‐O,N,O′:O)­bis­[tri­aqua­manganese(II)]–pyridine‐2,6‐di­carboxylic acid (1/2)

In the structure of the title compound, [Mn₂(C₇H₃NO₄)₂(H₂O)₆]·2C₇H₅NO₄, a centrosymmetric dinuclear complex, hexaa­aqua­bis­(pyri­dine‐2,6‐di­carboxyl­ato)­dimanganese(II) and free pyri­dine‐2,6‐di­carboxyl­ic acid are present in a 1:2 ratio. In the complex, each Mn²⁺ ion is coordinated by three O atoms and one N atom from the pyridine‐2,6‐di­carboxyl­ate ligands and by three water O atoms, resulting in a distorted pentagonal bipyramidal coordination. Within the centrosymmetric dinuclear complex, two Mn²⁺ ions are bridged by two carboxyl­ate O atoms. The crystal structure is stabilized by hydrogen bonds involving all the H atoms of the water ligands.     

Chelidamic acid monohydrate: the proton complex of a multidentate ligand

Chelidamic acid, 4‐hydroxy­pyridine‐2,6‐di­carboxyl­ic acid, is found to be zwitterionic in its solid monohydrate form, C₇H₅NO₅·H₂O, with the aryl­oxide and one carboxyl­ate group remaining protonated, but the other carboxyl­ate group losing its proton to the pyridine N atom. In this, it is unlike its parent, dipicolinic acid (pyridine‐2,6‐di­carboxyl­ic acid), which also crystallizes as a monohydrate, but one in which the acidic H atoms remain bound to the carboxyl­ate groups. In both structures, the water mol­ecule is a component of an extended hydrogen‐bonded network.     

catena‐Poly­[[(di‐2‐pyridyl­amine)­silver(I)]‐μ‐nicotinato] and catena‐poly­[[(di‐2‐pyridyl­amine)silver(I)]‐μ‐2,6‐di­hydroxy­benzoato]

In catena‐poly­[[(di‐2‐pyridyl­amine‐κ²N,N′)silver(I)]‐μ‐nico­tinato‐κ²N:O], [Ag(C₆H₄NO₂)(C₁₀H₉N₃)]_n, the Ag^I atom is tetracoordinated by two N atoms from the di‐2‐pyridyl­amine (BPA) ligand [Ag—N = 2.3785 (18) and 2.3298 (18) Å] and by one N atom and one carboxyl­ate O atom from nicotinate ligands [Ag—N = 2.2827 (15) Å and Ag—O = 2.3636 (14) Å]. Bridging by nicotinate N and O atoms generates a polymeric chain structure, which extends along [100]. The carboxyl O atom not bonded to the Ag atom takes part in an intrachain C—H⋯O hydrogen bond, further stabilizing the chain. Pairs of chains are linked by N—H⋯O hydrogen bonds to generate ribbons. There are no π–π interactions in this complex. In catena‐poly­[[(di‐2‐pyridyl­amine‐κ²N,N′)silver(I)]‐μ‐2,6‐di­hydroxy­benzoato‐κ²O¹:O²], [Ag(C₇H₅O₄)(C₁₀H₉N₃)]_n, the Ag^I atom has a distorted tetrahedral coordination, with three strong bonds to two pyridine N atoms from the BPA ligand [Ag—N = 2.286 (5) and 2.320 (5) Å] and to one carboxyl­ate O atom from the 2,6‐di­hydroxy­benzoate ligand [Ag—O = 2.222 (4) Å]; the fourth, weaker, Ag‐atom coordination is to one of the phenol O atoms [Ag⋯O = 2.703 (4) Å] of an adjacent moiety, and this interaction generates a polymeric chain along [100]. Pairs of chains are linked about inversion centers by N—H⋯O hydrogen bonds to form ribbons, within which there are π–π interactions. The ribbons are linked about inversion centers by pairs of C—H⋯O hydrogen bonds and additional π–π interactions between inversion‐related pairs of 2,6‐di­hydroxy­benzoate ligands to generate a three‐dimensional network.     

Bis(μ‐ethyl pyridine‐2,6‐di­carboxyl­ato)­bis­[di­aqua­chloro­cadmium(II)] dihydrate

The reaction of cadmium chloride with pyridine‐2,6‐di­carboxylic acid (PDA) and 98% H₂SO₄ in ethanol led to the formation of the title compound, bis­[μ‐6‐(ethoxy­carbonyl)­pyridine‐2‐carboxyl­ato]‐1:2κ⁴O⁶,N,O²:O²;1:2κ⁴O²:O²,N,O⁶‐bis­[di­aqua­chloro­cadmium(II)] dihydrate, [Cd₂(C₉H₈NO₄)₂Cl₂(H₂O)₄]·2H₂O. PDA is esterified to monoethyl ­pyridine‐2,6‐di­carboxyl­ate (MEPD) by the catalysis of H₂SO₄ during the reaction. The dinuclear Cd^II complex lies about an inversion centre and the unique Cd atom has a pentagonal–bipyramidal geometry. The two Cd atoms are bridged by two carboxyl­ate O atoms, forming a planar Cd₂O₂ unit. Stair‐like chains are formed via O—H⋯Cl hydrogen bonds and these are further arranged into two‐dimensional layers via hydrogen bonds involving solvate water mol­ecules.     

Linear chains in polymeric di­cyclo­hexyl­ammonium tri­butyl­(4‐oxo‐4H‐pyran‐2,6‐di­carboxyl­ato)­stannate and methyl­phenyl­ammonium tri­butyl(pyridine‐2,6‐di­carboxyl­ato)­stannate containing trigonal bipyramidal tin

catena‐Poly­[di­cyclo­hexyl­ammonium [tri­butyl­tin‐μ‐(4‐oxo‐4H‐pyran‐2,6‐di­carboxyl­ato‐O²:O⁶)]], (C₁₂­H₂₄N)­[Sn(C₇­H₂­O₆)(C₄H₉)₃], consists of 4‐oxo‐4H‐pyran‐2,6‐di­carboxyl­ato groups that axially link adjacent tri­butyl­tin units into a linear polyanionic chain. The ammonium counter‐ions surround the chain, and each cation forms a pair of hydrogen bonds to the double‐bond carbonyl O atoms of the same dianionic group. The chain propagates in a zigzag manner along the c axis of the monoclinic cell. In catena‐poly­[methyl­(phenyl)­ammonium [tri­butyl­tin‐μ‐(pyridine‐2,6‐di­carboxyl­ato‐O²:O⁶)]], (C₇H₁₀N)­[Sn(C₇H₃NO₄)­(C₄H₉)₃], the pyridine‐2,6‐di­carboxyl­ato groups also link the tri­butyl­tin groups into a chain, but the hydrogen‐bonded chain propagates linearly on the ac face of the monoclinic cell.     

Two new conformationally restricted 4,5‐dihydroxynorvaline analogues with a norbornane skeleton

The structures of two conformationally restricted 4,5‐di­hydroxy­norvaline analogues with a norbornane skeleton, namely methyl (1S,2S,3R,4R)‐2‐benz­amido‐3‐(1,2‐di­hydroxy­ethyl)­bi­cyclo[2.2.1]­heptane‐2‐carboxyl­ate, C₁₈H₂₃NO₅, and methyl (1R,2S,3R,4S)‐2‐benz­amido‐3‐(1,2‐di­hydroxy­ethyl)­bi­cyclo[2.2.1]­heptane‐2‐carboxyl­ate, C₁₈H₂₃NO₅, exhibit a conformation in the helical region of the ?,ψ map but their handedness is opposite. In both cases, the torsion angles (χ^1,1) giving the relative orientation of the 1,2‐di­hydroxy­ethyl group of the amino acid side chain and the benz­amide group of the peptide chain indicate that these groups adopt a nearly eclipsed conformation. Both compounds show a complex hydrogen‐bonding pattern.     

Polymeric aqua­(nitrato‐κ2O,O′)(1,10‐phenanthroline‐κ2N,N′)(2,3‐pyrazine­di­carboxyl­ato‐κ2N,O)­europium(III) monohydrate

In polymeric {[Eu(pzdc)(NO₃)(phen)(H₂O)]·H₂O}_n [pzdc is 2,3‐pyrazine­di­carboxyl­ate (C₆H₂O₄) and phen is 1,10‐phenanthroline (C₁₂H₈N₂)], each europium(III) ion is coordinated by seven O atoms (from three pzdc anions, a nitrate anion and a water mol­ecule) and the two N atoms of the phen ligand, resulting in a nine‐coordinated europium(III) center with a distorted monocapped square‐antiprismatic coordination polyhedron. Four pzdc anions bridge four europium(III) ions, forming a parallelogram unit, the four vertices of which are occupied by the four pzdc anions. Moreover, each parallelogram unit links six other adjacent parallelogram units, forming a two‐dimensional network with disordered lattice water mol­ecules.     

Di­aqua(2,2′‐bi­pyridine)­malonato­manganese(II)

In the crystal structure of the title compound, [Mn(C₃H₂O₄)(C₁₀H₈N₂)(H₂O)₂], the Mn^II atom demonstrates a distorted octahedral geometry, being coordinated by two N atoms of a 2,2′‐bi­pyridine ligand, two O atoms from the carboxyl­ate groups of the chelating malonate dianion and two O atoms of two cis water mol­ecules. The complex mol­ecules are linked to form a three‐dimensional supramolecular array by both hydrogen‐bonding interactions between coordinated water and the carboxyl­ate groups of neighboring mol­ecules and aromatic π–π‐stacking interactions of the bi­pyridine rings.     

Copper(II) and zinc(II) complexes of pyridine‐2,6‐di­carboxyl­ic acid

The title compounds, bis­(pyridine‐2,6‐di­carboxyl­ato‐N,O,O′)copper(II) monohydrate, [Cu(C₇H₄NO₄)₂]·H₂O, andbis(pyridine‐2,6‐dicarboxylato‐N,O,O′)zinc(II) trihydrate, [Zn(C₇H₄NO₄)₂]·3H₂O, have distorted octahedral geometries about the metal centres. Both metal ions are bonded to four O atoms and two pyridyl‐N atoms from the two terdentate ligand mol­ecules, which are nearly perpendicular to each other. The copper(II) complex has twofold crystallographic symmetry and contains two different ligand mol­ecules, one of which is neutral and another doubly ionized. In contrast, the zinc(II) complex contains two identical singly ionized ligand mol­ecules. Both crystal structures are stabilized by O—H?O intermolecular hydrogen bonds between the complex and the water mol­ecules.     

5‐n‐Butylpyridine‐2‐carboxylate–copper(II) and –iron(III) complexes

In trans‐bis(5‐n‐butyl­pyridine‐2‐carboxyl­ato‐κ²N,O)­bis­(methanol‐κO)copper(II), [Cu(C₁₀H₁₂NO₂)₂(CH₄O)₂], the Cu atom lies on a centre of symmetry and has a distorted octahedral coordination. The Cu—O(methanol) bond length in the axial direction is 2.596 (3) Å, which is much longer than the Cu—­O(carboxylate) and Cu—N distances in the equatorial plane [1.952 (2) and 1.977 (2) Å, respectively]. In mer‐tris(5‐n‐bu­tyl­pyridine‐2‐carboxyl­ato‐κ²N,O)­iron(III), [Fe(C₁₀H₁₂NO₂)₃], the Fe atom also has a distorted octahedral geometry, with Fe—O and Fe—N bond‐length ranges of 1.949 (4)–1.970 (4) and 2.116 (5)–2.161 (5) Å, respectively. Both crystals are stabilized by stacking interactions of the 5‐n‐butyl­pyridine‐2‐carboxyl­ate ligand, although hydrogen bonds also contribute to the stabilization of the copper(II) complex.     

catena‐Poly­[[di­aqua­(nicotinato‐κ2O,O′)­cadmium(II)]‐μ‐nicotinato‐κ3N:O,O′]

The title compound, [Cd(C₆H₄NO₂)₂(H₂O)₂]_n, forms a one‐dimensional chain structure based on a Cd atom with approximate pentagonal bipyramidal coordination geometry and two nicotinate ligands in different coordination modes. One acts as a tridentate ligand, chelating one Cd atom through the carboxyl­ate group while simultaneously binding to a second symmetry‐related Cd atom through the pyridine N atom; the other acts only as a bidentate ligand through its carboxyl­ate group. Hydro­gen bonds utilizing the coordinated water mol­ecules, uncoordinated nitro­gen and carboxyl­ate O atoms as acceptors link the chains.     

A one‐dimensional zigzag coordination polymer of di­aqua­(pyridine‐2,3‐di­carboxyl­ato)­cobalt(II)

The asymmetric unit of the title one‐dimensional coordination polymer, catena‐poly­[[μ‐pyridine‐2,3‐di­carb­oxyl­ato‐1κO:2κ²N,O′‐bis­[di­aqua­cobalt(II)]]‐μ‐pyridine‐2,3‐di­carboxyl­ato‐1κ²N,O:2κO′:1′κO′], [Co(C₇H₃NO₄)(H₂O)₂]_n, is composed of a cobalt(II) ion, a pyridine‐2,3‐di­carboxyl­ate dianion and two water mol­ecules. The polymer has a zigzag structure consisting of a chain of edge‐fused rings, and the polymer chains are linked by O—H⃛O hydrogen bonds into a three‐dimensional framework.     

Tetrakis(μ‐2,3‐dimethoxybenzoato)bis[(2,2′‐bipyridine)(2,3‐dimethoxybenzoato)lanthanum(III)]

The title compound, tetrakis(μ‐2,3‐di­methoxy­benzoato)‐κ⁴O:O′;κ⁶O,O′:O′‐bis[(2,2′‐bi­pyridine‐N,N′)(2,3‐di­methoxy­benzoato‐O,O′)lanthanum(III)], [La₂(2,3‐DMOBA)₆(2,2′‐bpy)₂], where 2,3‐DMOBA is 2,3‐di­methoxy­benzoate (C₉H₉O₄) and 2,2′‐bpy is 2,2′‐bi­pyridine (C₁₀H₈N₂), is a dimer with a centre of inversion between the La atoms bridged by four carboxyl­ate ligands. The central La atom is ennea‐coordinated and has a distorted monocapped square‐antiprism geometry.     

Polymeric hexa­aqua­hexakis(μ3‐2,2′‐oxy­diacetato)­trizinc(II)­digadolinium(III) dodecahydrate

A polymeric heterometallic compound, {[Gd₂Zn₃(C₄H₄O₅)₆(H₂O)₆]·12H₂O}_n, comprising zinc(II) and gadolinium(III) cations bridged by carboxyl­ate groups from oxy­di­acetate ligands, is presented. The Gd^III cations lie at sites with crystallographic 32 symmetry and display a tricapped trigonal‐prism arrangement, which is defined by six carboxyl and three ether O atoms. The Zn^II cations lie at sites with imposed 2/m symmetry and are octahedrally coordinated by four carboxyl O atoms and two apical water ligands, which form strong intramolecular hydrogen bonds. Comparison is made with the previously reported isostructural homologous copper–gadolinium complex.     

A single‐strand helical coordination polymer: catena‐poly­[[[tri­aqua­nickel(II)]‐μ‐2,2′‐bi­pyridine‐3,3′‐di­carboxyl­ato‐κ3N,N′:O] monohydrate]

The asymmetric unit of the title compound, {[Ni(C₁₂H₆N₂O₄)(H₂O)₃]·H₂O}_n, is composed of a lattice water mol­ecule and a nickel(II) ion that is coordinated by three water mol­ecules and the two N atoms of a 2,2′‐bi­pyridine‐3,3′‐di­carboxyl­ate ligand. The twist of the 2,2′‐bi­pyridine‐3,3′‐di­carboxyl­ate unit and the coordination of one carboxyl­ate group to a symmetry‐related Ni^II atom generate a helical chain that runs along the b axis. Intrahelical hydrogen bonds participate in controlling the orientation of the helices, and both right‐handed and left‐handed helices are connected by interhelical hydrogen bonds into two‐dimensional sheets.     

8‐Hydroxyquinaldinic acid and its nickel(II) complex

The molecules of 8‐hydroxy­quinolinium‐2‐carboxyl­ate, C₁₀H₇NO₃, have a planar structure, in which the carboxyl group is ionized and the ring N atom is protonated. The derived nickel(II) complex, bis(8‐hydroxy­quinoline‐2‐carboxyl­ato‐κ³O²,N,O⁸)­nickel(II) trihydrate, [Ni(C₁₀H₆NO₃)₂]·3H₂O, contains an octahedral central Ni^II ion coordinated by the hydroxyl O atom, the ring N atom and the carboxyl­ate O atom of each of the two tridentate ligands, with a perpendicular orientation of the quinoline rings.     

2‐Pyridone–tartronic acid (1/1), 3‐hydroxy­pyridinium hydrogen tartronate and 4‐hydroxy­pyridinium hydrogen tartronate

Tartronic acid forms a hydrogen‐bonded complex, C₅H₅NO·C₃H₄O₅, (I), with 2‐pyridone, while it forms acid salts, namely 3‐hydroxy­pyridinium hydrogen tartronate, (II), and 4‐hy­droxy­pyridinium hydrogen tartronate, (III), both C₅H₆NO⁺·C₃H₃O₅⁻, with 3‐hydroxy­pyridine and 4‐hydroxy­pyridine, respectively. In (I), the pyridone mol­ecules and the acid mol­ecules form R(8) and R(10) hydrogen‐bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N—H⋯O and O—H⋯O hydrogen bonds to form a hydrogen‐bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxyl­ate groups in (II) and (III).     

A one‐dimensional ladder‐like coordination polymer derived from chains formed via hydrogen bonds: catena‐poly­[[aqua­di­pyridine­nickel(II)]‐μ‐2,2′‐di­thio­dibenzoato‐κ3O,O′:O′′]

The title one‐dimensional chain nickel(II)–di­sulfide complex, [Ni(C₁₄H₈O₄S₂)(C₅H₅N)₂(H₂O)]_n, has each Ni^II cation coordinated by two N atoms from two pyridine ligands, three carboxyl­ate O atoms from two different di­thio­dibenzoate ligands and one O atom from a coordinated water mol­ecule, in a distorted octahedral coordination geometry. Each di­thio­dibenzoate ion links two Ni^II cations through its carboxyl­ate O atoms, making the structure polymeric. Hydro­gen‐bond interactions between two shoulder‐to‐shoulder chains lead to the formation of a ladder‐like structure.