O-atom Acceptors Research Articles

Ethyl 3-amino-5-bromo-1-benzofuran-2-carboxylate

The title compound, C11H10BrNO3, is close to planar with the benzo­furan unit and the ester group subtending a dihedral angle of 5.25 (2)°. The mol­ecular structure features an intra­molecular N—H⋯O inter­action. In the crystal, N—H⋯O hydrogen bonds involving carboxyl O-atom acceptors generate a chain extending along [201].

Proton-transfer compounds with 4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (sulfamethazine): the structures and hydrogen bonding in the salts with 5-nitrosalicylic acid and picric acid

The structures of the anhydrous proton-transfer compounds of the sulfa drug sulfamethazine with 5-nitrosalicylic acid and picric acid, namely 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2-hydroxy-5-nitrobenzoate, C12H15N4O2S(+)·C7H4NO4(-), (I), and 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2,4,6-trinitrophenolate, C12H15N4O2S(+)·C6H2N3O7(-), (II), respectively, have been determined. In the asymmetric unit of (I), there are two independent but conformationally similar cation-anion heterodimer pairs which are formed through duplex intermolecular N(+)-H···O(carboxylate) and N-H···O(carboxylate) hydrogen-bond pairs, giving a cyclic motif [graph set R2(2)(8)]. These heterodimers form separate and different non-associated substructures through aniline N-H···O hydrogen bonds, one one-dimensional, involving carboxylate O-atom acceptors, the other two-dimensional, involving both carboxylate and hydroxy O-atom acceptors. The overall two-dimensional structure is stabilized by π-π interactions between the pyrimidinium ring and the 5-nitrosalicylate ring in both heterodimers [minimum ring-centroid separation = 3.4580 (8) Å]. For picrate (II), the cation-anion interaction involves a slightly asymmetric chelating N-H···O R2(1)(6) hydrogen-bonding association with the phenolate O atom, together with peripheral conjoint R1(2)(6) interactions between the same N-H groups and O atoms of the ortho-related nitro groups. An inter-unit amine N-H···O(sulfone) hydrogen bond gives one-dimensional chains which extend along a and inter-associate through π-π interactions between the pyrimidinium rings [centroid-centroid separation = 3.4752 (9) Å]. The two structures reported here now bring to a total of four the crystallographically characterized examples of proton-transfer salts of sulfamethazine with strong organic acids.

Hydrogen bonding in two ammonium salts of 5-sulfosalicylic acid: ammonium 3-carboxy-4-hydroxybenzenesulfonate monohydrate and triammonium 3-carboxy-4-hydroxybenzenesulfonate 3-carboxylato-4-hydroxybenzenesulfonate

The structures of two ammonium salts of 3-carboxy-4-hydroxybenzenesulfonic acid (5-sulfosalicylic acid, 5-SSA) have been determined at 200 K. In the 1:1 hydrated salt, ammonium 3-carboxy-4-hydroxybenzenesulfonate monohydrate, NH4(+)·C7H5O6S(-)·H2O, (I), the 5-SSA(-) monoanions give two types of head-to-tail laterally linked cyclic hydrogen-bonding associations, both with graph-set R4(4)(20). The first involves both carboxylic acid O-H···O(water) and water O-H···O(sulfonate) hydrogen bonds at one end, and ammonium N-H···O(sulfonate) and N-H···O(carboxy) hydrogen bonds at the other. The second association is centrosymmetric, with end linkages through water O-H···O(sulfonate) hydrogen bonds. These conjoined units form stacks down c and are extended into a three-dimensional framework structure through N-H···O and water O-H···O hydrogen bonds to sulfonate O-atom acceptors. Anhydrous triammonium 3-carboxy-4-hydroxybenzenesulfonate 3-carboxylato-4-hydroxybenzenesulfonate, 3NH4(+)·C7H4O6S(2-)·C7H5O6S(-), (II), is unusual, having both dianionic 5-SSA(2-) and monoanionic 5-SSA(-) species. These are linked by a carboxylic acid O-H···O hydrogen bond and, together with the three ammonium cations (two on general sites and the third comprising two independent half-cations lying on crystallographic twofold rotation axes), give a pseudo-centrosymmetric asymmetric unit. Cation-anion hydrogen bonding within this layered unit involves a cyclic R3(3)(8) association which, together with extensive peripheral N-H···O hydrogen bonding involving both sulfonate and carboxy/carboxylate acceptors, gives a three-dimensional framework structure. This work further demonstrates the utility of the 5-SSA(-) monoanion for the generation of stable hydrogen-bonded crystalline materials, and provides the structure of a dianionic 5-SSA(2-) species of which there are only a few examples in the crystallographic literature.

Tetraaquabis(3,5-dinitrobenzoato-κO1)magnesium tetrahydrate

In the structure of the title compound, [Mg(C7H3N2O6)2(H2O)4]·4H2O, the slightly distorted octa­hedral MgO6 coord­in­ation polyhedron comprises two trans-related carboxyl­ate O-atom donors from mononodentate 3,5-dinitro­benzoate ligands, and four water mol­ecules. The coordinating water mol­ecules and the four water mol­ecules of solvation give both intra- and inter-unit O—H⋯O hydrogen-bonding inter­actions with carboxyl­ate, water and nitro O-atom acceptors, forming a three-dimensional structure.

2-(4-Aminobenzenesulfonamido)-4,6-dimethylpyrimidin-1-ium 2-carboxy-4,6-dinitrophenolate

In the structure of the phenolate salt of the sulfa drug sulfamethazine with 3,5-dinitro­salicylic acid, C12H15N4O2S+·C7H3N2O7 −, the dihedral angle between the pyrimidine and benzene rings of the cation is 59.70 (17)°. In the crystal, cation–anion hydrogen-bonding inter­actions involving pyrim­idine–carb­oxy N+—H⋯O and amine–carb­oxy N—H⋯O pairs give a cyclic R 2 2(8) motif while secondary N—H⋯O hydrogen bonds between the aniline group and both sulfone and nitro O-atom acceptors give a two-dimensional structure extending in (001).

Glabridin

In the title compound, C20H20O4 {systematic name: 4-[(3R)-8,8-dimethyl-3,4-dihydro-2H-pyrano[2,3-f]chromen-3-yl]benz­ene-1,3-diol}, the hydro­pyran ring linked to the pendant benzene ring adopts an envelope conformation, with the methyne C atom forming the flap. In the crystal, the –OH group at the 3-position of the benzene ring forms an O—H⋯O hydrogen bond to a chromene O-atom acceptor, whereas the –OH group at the 1-position forms an O—H⋯π inter­action with a neighboring benzene ring. The O—H⋯O hydrogen bonds form [001] chains and the O—H⋯π bonds cross-link the chains into (101) sheets. The absolute structure was assumed to be the same as that deduced from previous studies for the natural product.

(Z)-Ethyl 2-chloro-2-[2-(4-methylphenyl)hydrazinylidene]acetate

The mol­ecule of the title compound, C11H13ClN2O2, is approximately planar (r.m.s. deviation = 0.099 Å for non-H atoms) and adopts a Z conformation about the C=N double bond. In the crystal, mol­ecules are linked by N—H⋯O and C—H⋯O hydrogen bonds to the same O-atom acceptor, forming zigzag chains propagating along [010]. These inter­actions give rise to R 2 1(6) loops.

Quinolinium 8-hy-droxy-7-iodo-quinoline-5-sulfonate 0.8-hydrate.

In the crystal structure of the title hydrated quinolinium salt of ferron (8-hy­droxy-7-iodo­quinoline-5-sulfonic acid), C9H7N+·C9H5INO4S−·0.8H2O, the quinolinium cation is fully disordered over two sites (occupancy factors fixed at 0.63 and 0.37) lying essentially within a common plane and with the ferron anions forming π–π-associated stacks down the b axis [minimum ring centroid separation = 3.462 (6) Å]. The cations and anions are linked into chains extending along c through hy­droxy O—H⋯O and quinolinium N—H⋯O hydrogen bonds to sulfonate O-atom acceptors which are also involved in water O—H⋯O hydrogen-bonding inter­actions along b, giving a two-dimensional network.

Isopropyl 2,2-bis(4-bromophenyl)-2-hydroxyacetate

The title compound, C17H16Br2O3, which is a restricted commercial acaricide (common name bromo­propyl­ate), has two independent and conformationally similar mol­ecules in the asymmetric unit [dihedral angles between the planes of the two phenyl rings = 68.7 (4) and 77.4 (5)°]. The C atoms of the isopropyl group of one of the mol­ecules are disordered over two sites with occupancies of 0.638 (16) and 0.362 (16). Minor non-merohedral twinning was also present in the crystal. Inter­molecular O—H⋯O hydrogen-bonding inter­actions involving the hy­droxy groups and carboxyl O-atom acceptors give separate centrosymmetric homodimers through cyclic hydrogen-bonding motifs [graph set R 2 2(10)].

N,N′-(4,5-Dimethyl-1,2-phenylene)bis(pyridine-2-carboxamide)

In the title compound, C20H18N4O2, the dihedral angles between the central benzene ring and the pyridine rings are 57.55 (6) and 22.05 (8)°. The mol­ecular conformation is stabilized by intra­molecular N—H⋯N inter­actions and in the crystal structure an inter­molecular asymmetric cyclic hydrogen-bonding association involving both amide N—H donors and a common amide O-atom acceptor gives a chain extending along the c axis.

Ligand-Based Reduction of CO2 and Release of CO on Iron(II)

A synthetic cycle for the CO(2)-to-CO conversion (with subsequent release of CO) based on iron(II), a redox-active pydridinediimine ligand (PDI), and an O-atom acceptor is reported. This conversion is a passive-type ligand-based reduction, where the electrons for the CO(2) conversion are supplied by the reduced PDI ligand and the ferrous state of the iron is conserved.

Poly[[diaquabis[μ-2-(4-fluorophenoxy)acetato-κ2O1:O1′]magnesium] 0.4-hydrate

In the title compound, {[Mg(C8H6FO3)2(H2O)2]·0.4H2O}n, slightly distorted octa­hedral MgO6 complex units have crystallographic inversion symmetry, the coordination polyhedron comprising two trans-related water mol­ecules and four carboxyl O-atom donors, two of which are bridging. Within the two-dimensional complex polymer which is parallel to (100), coordinating water mol­ecules form inter­molecular O—H⋯O hydrogen bonds with carboxyl­ate and phen­oxy O-atom acceptors, as well as with the partial-occupancy solvent water mol­ecules.

Hydrogen bonding in cyclic imides and amide carboxylic acid derivatives from the facile reaction ofcis-cyclohexane-1,2-carboxylic anhydride witho- andp-anisidine andm- andp-aminobenzoic acids

The structures of the open-chain amide carboxylic acid rac-cis-2-[(2-methoxyphenyl)carbamoyl]cyclohexane-1-carboxylic acid, C(15)H(19)NO(4), (I), and the cyclic imides rac-cis-2-(4-methoxyphenyl)-3a,4,5,6,7,7a-hexahydroisoindole-1,3-dione, C(15)H(17)NO(3), (II), chiral cis-3-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)benzoic acid, C(15)H(15)NO(4), (III), and rac-cis-4-(1,3-dioxo-3a,4,5,6,7,7a-hexahydroisoindol-2-yl)benzoic acid monohydrate, C(15)H(15)NO(4)·H(2)O, (IV), are reported. In the amide acid (I), the phenylcarbamoyl group is essentially planar [maximum deviation from the least-squares plane = 0.060 (1) Å for the amide O atom] and the molecules form discrete centrosymmetric dimers through intermolecular cyclic carboxy-carboxy O-H···O hydrogen-bonding interactions [graph-set notation R(2)(2)(8)]. The cyclic imides (II)-(IV) are conformationally similar, with comparable benzene ring rotations about the imide N-C(ar) bond [dihedral angles between the benzene and isoindole rings = 51.55 (7)° in (II), 59.22 (12)° in (III) and 51.99 (14)° in (IV)]. Unlike (II), in which only weak intermolecular C-H···O(imide) hydrogen bonding is present, the crystal packing of imides (III) and (IV) shows strong intermolecular carboxylic acid O-H···O hydrogen-bonding associations. With (III), these involve imide O-atom acceptors, giving one-dimensional zigzag chains [graph-set C(9)], while with the monohydrate (IV), the hydrogen bond involves the partially disordered water molecule which also bridges molecules through both imide and carboxy O-atom acceptors in a cyclic R(4)(4)(12) association, giving a two-dimensional sheet structure. The structures reported here expand the structural database for compounds of this series formed from the facile reaction of cis-cyclohexane-1,2-dicarboxylic anhydride with substituted anilines, in which there is a much larger incidence of cyclic imides compared to amide carboxylic acids.

4-{[4-(Hy-droxy-meth-yl)piperidin-1-yl]meth-yl}phenol.

In the title compound, C13H19NO2, the piperidine ring has a chair conformation with the exocyclic N—C bond in an equatorial position. In the crystal, mol­ecules are linked head-to-tail by phenol O—H⋯O hydrogen bonds to hy­droxy­methyl­ene O-atom acceptors, forming chains which extend along [100]. These chains form two-dimensional networks lying parallel to (101) through cyclic hydrogen-bonding associations [graph set R 4 4(30)], involving hy­droxy O—H donors and piperidine N-atom acceptors.

2-Amino-5-methylpyridinium nitrate

In the title salt, C6H9N2 +·NO3 −, the 2-amino-5-methyl­pyridinium cation and the nitrate anion are cyclically linked through pyridinium and amine N—H⋯O hydrogen bonds [graph set R 4 3(12)]. These units are extended into a zigzag chain structure lying parallel to the a axis, through a second cyclic R 2 2(8) association involving amine N—H⋯O and aromatic C—H⋯O hydrogen bonds to nitrate O-atom acceptors.

Bis(benzylaminium) 4,5-dichlorobenzene-1,2-dicarboxylate monohydrate

In the structure of the title salt, 2C7H10N+·C8H2Cl2O4 2−·H2O, the two benzyl­aminium anions have different conformations, one being essentially planar and the other having the side chain rotated out of the benzene plane [minimum ring to side-chain C—C—C—N torsion angles = −3.6 (6) and 50.1 (5)°, respectively]. In the 4,5-dichloro­phthalate dianion, the carboxyl­ate groups make dihedral angles of 23.0 (2) and 76.5 (2)° with the benzene ring. In the crystal, aminium N—H⋯O and water O—H⋯O hydrogen-bonding associations with carboxyl­ate O-atom acceptors give a two-dimensional duplex sheet structure which extends along the (011) plane. Weak π–π inter­actions are also present between the benzene ring of the dianion and one of the cation rings [minimum ring centroid separation = 2.749 (3) Å].

Diaquabis{4-[(pyridin-2-yl)methylideneamino]benzenesulfonato-κ2 N,N′}nickel(II) tetrahydrate

In the title complex, [Ni(C12H9N2O3S)2(H2O)2]·4H2O, the NiII ion is coordinated by four N atoms from two bidentate chelating 4-[(pyridin-2-yl)methyl­idene­amino]­benzene­sulfonate ligands and two O atoms from cis-related water mol­ecules in a slightly distorted octa­hedral environment [Ni—N = 2.071 (3)–2.121 (3) Å and Ni—O = 2.071 (2) and 2.073 (3) Å]. In the crystal, the coordinated water mol­ecules and the four water mol­ecules of solvation are involved in inter­molecular O—H⋯O hydrogen-bonding inter­actions with water and sulfon­ate O-atom acceptors, giving a three-dimensional framework structure.

1H-Pyrazol-2-ium hydrogen oxalate

In the title compound, C3H5N2 +·C2HO4 −, the anions form centrosymmetric dimers through cyclic O—H⋯O hydrogen-bonding associations [graph set R 2 2(10)]. These dimers are then linked through a cyclic R 4 2(10) N—H⋯O hydrogen-bonding association involving two cations and the carboxyl O-atom acceptors of separate anions, giving chain structures extending across the (111) plane.

Rac-3-exo-Ammonio-7-anti-carboxytricyclo[2.2.1.0.2,6]heptane-3-endo-carboxylate monohydrate

The racemic title compound, C9H11NO4·H2O, a tricyclic rearranged amino­norbornane dicarb­oxy­lic acid, is a conformationally rigid analogue of glutamic acid and exists as an ammonium-carboxyl­ate zwitterion, with the bridghead carb­oxy­lic acid group anti-related. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds involving the ammonium, carb­oxy­lic acid and water donor groups with both water and carboxyl O-atom acceptors give a three-dimensional framework structure.

Dimethyl 5,5′-methylenebis(2-hydroxybenzoate)

In the title compound, C17H16O6, the two methyl salicylate moieties are related by crystallographic twofold rotational symmetry with the two benzene rings close to being perpendicular [inter-ring dihedral angle = 86.6 (8)°]. Intra­molecular phenolic O—H⋯O hydrogen bonds with carboxyl O-atom acceptors are present, with these groups also involved in centrosymmetric cyclic inter­molecular O—H⋯O hydrogen-bonding associations [graph set R 2 2(4)], giving infinite chains extending across (101).