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.     

Zwitterionic 4‐piperidine­carboxyl­ic acid monohydrate

The title compound, 4‐piperidinio­carboxyl­ate (isonipecotic acid), crystallizes as a zwitterion and incorporates one water mol­ecule, i.e. C₆H₁₁NO₂·H₂O. The piperidine ring adopts a chair conformation and the α‐carboxyl­ate group is oriented in the equatorial position. The combination of the interactions between the α‐amino and α‐carboxyl­ate groups and the water mol­ecules builds a three‐dimensional assembly of hydrogen bonds.     

Bis(μ‐3‐nitrobenzene‐1,2‐dicarboxyl­ato)‐κ8O1,O2:O2,O3;O3,O2:O2,O1‐bis­[triaqua­(2‐carboxy‐3‐nitro­benzoato‐κ2O,O′)lanthanum(III)] dihydrate

The title compound, [La₂(C₈H₃NO₆)₂(C₈H₄NO₆)₂(H₂O)₆]·2H₂O, consists of dimeric units related by an inversion center. The two La^III atoms are linked by two bridging bidentate carboxyl­ate groups and two monodentate carboxyl­ate groups. Each La^III atom is nine‐coordinated by six O atoms from five different carboxyl­ate groups and three from water mol­ecules. Hydrogen bonds between the water mol­ecules and between the solvent water and a carboxyl­ate O atom are observed in the structure. In the crystal packing, there are slipped π–π stacking inter­actions between the parallel benzene rings. Both hydrogen‐bonding and π–π inter­actions combine to stabilize the three‐dimensional supra­molecular network.     

Tetrakis(2,2′‐bipyridine‐κ2N,N′)­tetrakis(μ‐salicyl­ato‐κ3O,O′:O′′)‐quadro‐tetrazinc(II) decahydrate

The title compound, [Zn₄(C₇H₄O₃)₄(C₁₀H₈N₂)₄]·10H₂O, crystallizes as a centrosymmetric tetranuclear cyclic complex containing four Zn^II atoms bridged by four carboxyl­ate groups from salicyl­ate ligands, with a syn–anti configuration. Each Zn^II atom has a distorted trigonal–bipyramidal coordination geometry, formed by two N atoms of a 2,2′‐bipyridine ligand and three O atoms from two salicyl­ate ligands. The complex is stabilized by intramolecular π–π interactions between pairs of bi­pyridine rings and a 16‐membered gear‐wheel‐shaped cyclic framework. The hydrogen‐bonding network is formed via the water mol­ecules.     

Crystal engineering with heteroboranes. II. 1,2‐Di­carboxy‐1,2‐dicarba‐closo‐dodecaborane(12) ethanol hemisolvate

The title compound, 1,2‐(COOH)₂‐1,2‐closo‐C₂B₁₀H₁₀·0.5C₂H₆O or C₄H₁₂B₁₀O₄·0.5C₂H₆O, forms a tetramer by incorporating ethanol (solvent) mol­ecules through hydrogen bonding. Two eight‐membered rings [graph set R(8)] are formed by hydrogen bonding between two carboxyl­ic acid groups, whereas two ten‐membered rings [R(10)] are formed by hydrogen bonding between two carboxyl­ic acid groups and the OH group of an ethanol mol­ecule (solvent). Two crystallographically independent tetramers are present in the crystal structure.     

2‐Amino‐5‐chloro‐1,3‐benzoxazol‐3‐ium 2‐(3,4‐di­chloro­phenoxy)­acetate

The 1:1 organic salt of the title compound, C₇H₆ClN₂O⁺·C₈H₅Cl₂O₃^? or [(2‐ABOX)(3,4‐D)], comprises the two constituent mol­ecules associated by an R₂²(8) graph‐set interaction through the carboxyl­ate group of 3,4‐D across the protonated N/N sites of 2‐ABOX [N?O 2.546 (3) and 2.795 (3) Å]. Cation/anion pairs associate across an inversion centre forming discrete tetramers via an additional three‐centre hydrogen‐bonding association from the latter N amino proton to a phenoxy O atom [N?O 3.176 (3) Å] and a carboxyl­ate O atom [N?O 2.841 (3) Å]. This formation differs from the polymeric hydrogen‐bonded chains previously observed for adduct structures of 2‐ABOX with carboxyl­ic acids.     

Tetrakis[(4‐aminopyridinio)acetato‐κO]diaquamanganese(II) diper­chlorate

In the centrosymmetric title complex, [Mn(C₇H₈N₂O₂)₄(H₂O)₂](ClO₄)₂, the Mn^II ion is in an octahedral environment, with the equatorial plane being defined by the O atoms of four monodentate carboxyl­ate groups, and the octahedron being completed by two trans‐coordinated water mol­ecules. There are intramolecular hydrogen bonds between the coordinated water mol­ecules and the non‐coordinated O atoms of the carboxyl­ate groups. Hydrogen bonds between the amino groups and the carboxyl­ate groups of neighbouring mol­ecules generate a layered hydrogen‐bonded network.     

Cobalt(II) and nickel(II) complexes of quinoline‐2‐carboxyl­ate

The title complexes, trans‐di­aqua­bis­(quinoline‐2‐carboxyl­ato‐κ²N,O)­cobalt(II)–water–methanol (1/2/2), [Co(C₁₀H₆NO₂)₂(H₂O)₂]·2CH₄O·2H₂O, and trans‐di­aqua­bis­(quinoline‐2‐car­box­yl­ato‐κ²N,O)­nickel(II)–water–methanol (1/2/2), [Ni(C₁₀H₆NO₂)₂(H₂O)₂]·2CH₄O·2H₂O, are isomorphous and contain Co^II and Ni^II ions at centers of inversion. Both complexes have the same distorted octahedral coordination geometry, and each metal ion is coordinated by two quinoline N atoms, two carboxyl­ate O atoms and two water O atoms. The quinoline‐2‐carboxyl­ate ligands lie in trans positions with respect to one another, forming the equatorial plane, with the two water ligands occupying the axial positions. The complex mol­ecules are linked together by hydrogen bonding involving a series of ring patterns which include the uncoordinated water and methanol mol­ecules.     

Methyl 4‐amino‐2,3‐dihydro‐6‐methoxy‐1,3‐dioxo‐1H‐pyrrolo[3,4‐c]pyridine‐7‐carboxylate forms hydrogen‐bonded sheets built from R22(8) and R66(42) rings

In the title compound, C₁₀H₉N₃O₅, which was formed by the reaction of 6‐amino‐2‐methoxy‐4(3H)‐pyrimidinone with di­methyl acetyl­enedi­carboxyl­ate, the mol­ecules are linked by N—H?O hydrogen bonds [N?O 2.8974 (15) and 3.0300 (15) Å, and N—H?O 165 and 174°] into planar sheets built from alternating R₂²(8) and R₆⁶(42) rings.     

Sodium pyridine‐3‐carboxyl­ate

The title compound, also known as sodium nicotinate, Na⁺·C₆H₄NO₂⁻, consists of two unique Na atoms coordinated to two unique pyridine‐3‐­carboxyl­ate ligands through the N atoms and carboxylate groups. One Na atom and one pyridine‐3‐­carboxyl­ate ligand lie on a twofold axis. Extensive Na coordination results in a three‐dimensional array comprising infinite NaO₂CR chains linked by intrachain Na—N bonds.     

catena‐Poly[[bis[pentaaquaerbium(III)]‐μ‐benzenehexacarboxylato] tetrahydrate]

The title compound is composed of one‐dimensional polymeric {[Er₂(C₁₂O₁₂)(H₂O)₁₀]·4H₂O}_n chains containing Er in a slightly distorted antiprismatic eightfold coordination. The benzene­hexa­carboxyl­ate ion is located about an inversion centre. Water mol­ecules of crystallization, linked by hydrogen bonding to water mol­ecules of the rare earth coordination spheres or the carboxyl­ate groups of the organic ligands, fill the space generated by the packing of the separated chains.     

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.     

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.     

catena‐Poly­[[di­aqua­(isonicotinato‐O,O′)­europium(III)]‐di‐μ‐isonicotin­ato‐O:O′]

The title complex, [Eu(C₆H₄O₂)₃(H₂O)₂], has a double carboxyl­ate‐bridged infinite‐chain structure, with one chelating carboxyl­ate group on each Eu ion centre, which also binds to two water mol­ecules to yield an eight‐coordinate square‐antiprismatic geometry, with Eu—O bond lengths in the range 2.338 (3)–2.594 (3) Å. The pyridine N atoms of the isonicotinate groups do not coordinate to the Eu ions; instead, they direct the formation of Eu^III coordination polymers via hydrogen bonding with coordinated water mol­ecules.     

Tetra­ammonium benzene‐1,2,4,5‐tetra­carboxyl­ate tetrahydrate

The anions in the title compound, 4NH₄⁺·C₁₀H₂O₈^4?·4H₂O, are held together by regular hydrogen bonds from the carboxyl­ate O atoms to the ammonium cations and water mol­ecules, forming a three‐dimensional network.     

Bis­(di­cyclo­hexyl­ammonium) adipate monohydrate

In the asymmetric unit of the title compound, 2C₁₂H₂₄N⁺·C₆H₈O₄^2?·H₂O, the carboxyl­ate ion lies about an inversion center, the water mol­ecule is on a twofold axis and the sec‐ammonium cation is in a general position. Cations link the oxy­gen ends of two adjacent carboxyl­ate anions to form an eight‐membered ring [N?O 2.683 (3) and 2.711 (3) Å]. The ion pair propagates as a linear chain and adjacent chains are linked through the water mol­ecules [O?O 2.966 (3) Å] into layers.     

Proton‐transfer and non‐transfer in compounds of quinoline and quinaldic acid with l‐tartaric acid

The structures of two compounds of l ‐tartaric acid with quinoline, viz. the proton‐transfer compound quinolinium hydrogen (2R,3R)‐tartrate monohydrate, C₉H₈N⁺·C₄H₅O₆⁻·H₂O, (I), and the anhydrous non‐proton‐transfer adduct with quinaldic acid, bis­(quinolinium‐2‐carboxyl­ate) (2R,3R)‐tar­taric acid, 2C₁₀H₇NO₂·C₄H₆O₆, (II), have been determined at 130 K. Compound (I) has a three‐dimensional honeycomb substructure formed from head‐to‐tail hydrogen‐bonded hydrogen tartrate anions and water mol­ecules. The stacks of π‐bonded quinolinium cations are accommodated within the channels and are hydrogen bonded to it peripherally. Compound (II) has a two‐dimensional network structure based on pseudo‐centrosymmetric head‐to‐tail hydrogen‐bonded cyclic dimers comprising zwitterionic quinaldic acid species which are inter­linked by tartaric acid mol­ecules.     

catena‐Poly­[[tetra­aqua­iron(II)]‐μ‐succinato‐κ2O:O′]

The title complex, {[Fe(C₄H₄O₄)(H₂O)₄]}_n, is an infinite poly­meric compound bridged by the succinate dianion. Two carboxyl­ate groups coordinate in a monodentate manner to the Fe^II atom, in a trans fashion, with an O—Fe—O bond angle of 175.72 (6)° and Fe—O distances of 2.0886 (14) and 2.1008 (15) Å. One of the uncoordinated carboxyl­ate O atom forms an intramolecular hydrogen bond with a coordinated water mol­ecule. Extensive hydrogen bonding between parallel poly­meric complex chains results in a three‐dimensional supramolecular structure.     

Bis(μ‐2‐sulfonatobenzoato)bis[(1,10‐phenanthroline)­lead(II)] dihydrate

In the title centrosymmetric dimer, [Pb₂(sbc)₂(phen)₂]·2H₂O [sbc is the 2‐sulfonatobenzoate dianion (C₇H₄O₅S) and phen is 1,10‐phenanthroline (C₁₂H₈N₂)], each Pb^II ion is six‐coordinated by four O atoms, viz. carboxyl­ate and sulfonate O atoms from two sbc anions, and two N atoms from a 1,10‐phenanthroline ligand. One 1,10‐phenanthroline ligand and the carboxyl­ate group of one sbc ligand are chelated to each Pb^II cation, and the sulfonate group of the other sbc unit is monodentate. One O atom of the chelated carboxyl­ate group also bridges to the other Pb^II cation, so that each pair of Pb^II ions is bridged by two sbc anions and has the same coordination environment, forming a dinuclear ring. Each pair of Pb^II ions is thus connected by two different kinds of bridges, namely a carboxyl­ate short bridge and a carboxyl­ate–sulfonate long bridge. There is also a special position of site symmetry at the centre of the two Pb^II cations.     

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).