Nitro O-atom Research Articles

Catena-Poly[[bis-(di-aqua-lithium)]-μ4-3,3',5,5'-tetra-nitro-4,4'-bi-pyrazole-1,1'-diido]: a new moisture-insensitive alkali-metal energetic salt with a well-defined network structure.

In the structure of the title salt, [Li2(C6N8O8)(H2O)4]n, the 3,3',5,5'-tetra-nitro-4,4'-bi-pyrazole-1,1'-diide dianion [{TNBPz}2-] is situated across the twofold axis. The distorted coordination octa-hedra around Li+ involve four short bonds with two pyrazolate N atoms and two aqua ligands [Li-N(O) = 1.999 (3)-2.090 (2) Å] and two longer contacts with nitro-O atoms [2.550 (2), 2.636 (2) Å]. When combined with μ4-{TNBPz}2-, this generates a mono-periodic polymeric structure incorporating discrete centrosymmeric [(H2O)2Li-(di-nitro-pyrazolato)2-Li(H2O)2] units. The three-dimensional stack of mutually orthogonal coordination chains is reminiscent of a Lincoln log pattern. It is influenced by conventional hydrogen bonding [O⋯O = 2.8555 (17)-3.0010 (15) Å] and multiple lone pair-π hole inter-actions of the nitro groups [N⋯O = 3.0349 (15) and 3.0887 (15) Å]. The Hirshfeld surface and two-dimensional fingerprint plots also support the significance of non-covalent bonding. Coordinative saturation and a favorable geometry at the Li+ ions, dense packing of the polymeric subconnectivities and particularly extensive inter-anion inter-actions may be involved in the stabilization of the structure. The title salt is a rare example of an energetic Li nitro-azolate, which nicely crystallizes from aqueous solution and is neither hygroscopic nor efflorescent. The TG/DTA data reveal total dehydration in the range of 330-430 K and stability of the anhydrous material up to 633-653 K.

Isostructural rubidium and caesium 4-(3,5-di-nitro-pyrazol-4-yl)-3,5-di-nitro-pyrazolates: crystal engineering with polynitro energetic species.

In the structures of the title salts, poly[[μ4-4-(3,5-di-nitro-pyrazol-4-yl)-3,5-di-nitro-pyrazol-1-ido]rubidium], [Rb(C6HN8O8)] n , (1), and its isostructural caesium analogue [Cs(C6HN8O8) n , (2), two independent cations M1 and M2 (M = Rb, Cs) are situated on a crystallographic twofold axis and on a center of inversion, respectively. Mutual inter-molecular hydrogen bonding between the conjugate 3,5-dinito-pyrazole NH-donor and 3,5-di-nitro-pyrazole N-acceptor sites of the anions [N⋯N = 2.785 (2) Å for (1) and 2.832 (3) Å for (2)] governs the self-assembly of the translation-related anions in a predictable fashion. Such one-component modular construction of the organic subtopology supports the utility of the crystal-engineering approach towards designing the structures of polynitro energetic materials. The anionic chains are further linked by multiple ion-dipole inter-actions involving the 12-coordinate cations bonded to two pyrazole N-atoms [Rb-N = 3.1285 (16), 3.2261 (16) Å; Cs-N = 3.369 (2), 3.401 (2) Å] and all of the eight nitro O-atoms [Rb-O = 2.8543 (15)-3.6985 (16) Å; Cs-O = 3.071 (2)-3.811 (2) Å]. The resulting ionic networks follow the CsCl topological archetype, with either metal or organic ions residing in an environment of eight counter-ions. Weak lone pair-π-hole inter-actions [pyrazole-N atoms to NO2 groups; N⋯N = 2.990 (3)-3.198 (3) Å] are also relevant to the packing. The Hirshfeld surfaces and percentage two-dimensional fingerprint plots for (1) and (2) are described.

2-Methyl-4-(4-nitro-phen-yl)but-3-yn-2-ol: crystal structure, Hirshfeld surface analysis and computational chemistry study.

The di-substituted acetyl-ene residue in the title compound, C11H11NO3, is capped at either end by di-methyl-hydroxy and 4-nitro-benzene groups; the nitro substituent is close to co-planar with the ring to which it is attached [dihedral angle = 9.4 (3)°]. The most prominent feature of the mol-ecular packing is the formation, via hy-droxy-O-H⋯O(hy-droxy) hydrogen bonds, of hexa-meric clusters about a site of symmetry . The aggregates are sustained by 12-membered {⋯OH}6 synthons and have the shape of a flattened chair. The clusters are connected into a three-dimensional architecture by benzene-C-H⋯O(nitro) inter-actions, involving both nitro-O atoms. The aforementioned inter-actions are readily identified in the calculated Hirshfeld surface. Computational chemistry indicates there is a significant energy, primarily electrostatic in nature, associated with the hy-droxy-O-H⋯O(hy-droxy) hydrogen bonds. Dispersion forces are more important in the other identified but, weaker inter-molecular contacts.

Proton-transfer compounds featuring the unusual 4-arsonoanilinium cation from the reaction of (4-aminophenyl)arsonic acid with strong organic acids

Abstract The crystal structures of the 1:1 proton-transfer compounds of (4-aminophenyl)arsonic acid (p-arsanilic acid) with the strong organic acids, 2,4,6-trinitrophenol (picric acid), 3,5-dinitrosalicylic acid, (3-carboxy-4-hydroxy)benzenesulfonic acid (5-sulfosalicylic acid) and toluene-4-sulfonic acid have been determined at 200 K and their hydrogen–bonding patterns examined. The compounds are, respectively, anhydrous 4-arsonoanilinium 2,4,6-trinitrophenolate (1), the hydrate 4-arsonoanilinium 2-carboxy-4,6-dinitrophenolate monohydrate (2), the hydrate 4-arsonoanilinium (3-carboxy-4-hydroxy)benzenesulfonate monohydrate (3) and the partial solvate 4-arsonoanilinium toluene-4-sulfonate 0.8 hydrate (4). The asymmetric unit of 2, a phenolate, comprises two independent but conformationally similar cation-anion pairs and two water molecules of solvation, and in all compounds, extensive inter-species hydrogen–bonding interactions involving arsono O–H···O and anilinium N–H···O hydrogen–bonds generate three-dimensional supramolecular structures. In the cases of 1 and 2, the acceptors include phenolate and nitro O-atom acceptors, with 3 and 4, additionally, sulfonate O-atom acceptors, and with the hydrates 2–4, the water molecules of solvation. A feature of the hydrogen–bonding in 3 is the presence of primary chains extending along (010) through centrosymmetric cyclic R 2 2(8) motifs together with conjoined cyclic R 3 4(12) motifs, which include the water molecule of solvation. The primary hydrogen–bonding in the substructure of 4 involves homomolecular cation–cation arsono O–H···O interactions forming columns down the crystallographic four-fold axis of the unit cell.

Hydrazinium 2-amino-4-nitro-benzoate dihydrate: crystal structure and Hirshfeld surface analysis.

In the anion of the title salt hydrate, H5N2+·C7H5N2O4-·2H2O, the carboxyl-ate and nitro groups lie out of the plane of the benzene ring to which they are bound [dihedral angles = 18.80 (10) and 8.04 (9)°, respectively], and as these groups are conrotatory, the dihedral angle between them is 26.73 (15)°. An intra-molecular amino-N-H⋯O(carboxyl-ate) hydrogen bond is noted. The main feature of the crystal packing is the formation of a supra-molecular chain along the b axis, with a zigzag topology, sustained by charge-assisted water-O-H⋯O(carboxyl-ate) hydrogen bonds and comprising alternating twelve-membered {⋯OCO⋯HOH}2 and eight-membered {⋯O⋯HOH}2 synthons. Each ammonium-N-H atom forms a charge-assisted hydrogen bond to a water mol-ecule and, in addition, one of these forms a hydrogen bond with a nitro-O atom. The amine-N-H atoms form hydrogen bonds to carboxyl-ate-O and water-O atoms, and the amine N atom accepts a hydrogen bond from an amino-H atom. The hydrogen bonds lead to a three-dimensional architecture. An analysis of the Hirshfeld surface highlights the major contribution of O⋯H/H⋯O hydrogen bonding to the overall surface, i.e. 46.8%, compared with H⋯H contacts (32.4%).

Cyclic heterotetrameric and low-dimensional hydrogen-bonded polymeric structures in the morpholinium salts of ring-substituted benzoic acid analogues.

The morpholinium (tetrahydro-2H-1,4-oxazin-4-ium) cation has been used as a counter-ion in both inorganic and organic salt formation and particularly in metal complex stabilization. To examine the influence of interactive substituent groups in the aromatic rings of benzoic acids upon secondary structure generation, the anhydrous salts of morpholine with salicylic acid, C4H10NO(+)·C7H5O3(-), (I), 3,5-dinitrosalicylic acid, C4H10NO(+)·C7H3N2O7(-), (II), 3,5-dinitrobenzoic acid, C4H10NO(+)·C7H3N2O6(-), (III), and 4-nitroanthranilic acid, C4H10NO(+)·C7H5N2O4(-), (IV), have been prepared and their hydrogen-bonded crystal structures are described. In the crystal structures of (I), (III) and (IV), the cations and anions are linked by moderately strong N-H...Ocarboxyl hydrogen bonds, but the secondary structure propagation differs among the three, viz. one-dimensional chains extending along [010] in (I), a discrete cyclic heterotetramer in (III), and in (IV), a heterotetramer with amine N-H...O hydrogen-bond extensions along b, giving a two-layered ribbon structure. With the heterotetramers in both (III) and (IV), the ion pairs are linked though inversion-related N-H...Ocarboxylate hydrogen bonds, giving cyclic R4(4)(12) motifs. With (II), in which the anion is a phenolate rather than a carboxylate, the stronger assocation is through a symmetric lateral three-centre cyclic R1(2)(6) N-H...(O,O') hydrogen-bonding linkage involving the phenolate and nitro O-atom acceptors of the anion, with extension through a weaker O-H...Ocarboxyl hydrogen bond. This results in a one-dimensional chain structure extending along [100]. In the structures of two of the salts [i.e. (II) and (IV)], there are also π-π ring interactions, with ring-centroid separations of 3.5516 (9) and 3.7700 (9) Å in (II), and 3.7340 (9) Å in (IV).

Crystal structure of 3-chloro-1-methyl-5-nitro-1H-indazole.

The mol­ecule of the title compound, C8H6ClN3O2, is built up from fused five- and six-membered rings connected to a chlorine atom and to nitro and methyl groups. The indazole system is essentially planar with the largest deviation from the mean plane being 0.007 (2) Å. No classical hydrogen bonds are observed in the structure. Two mol­ecules form a dimer organised by a symmetry centre via a close contact between a nitro-O atom and the chlorine atom [at 3.066 (2) Å this is shorter than the sum of their van der Waals radii].

The structures of the isomorphous potassium and rubidium salts of 4-nitrobenzoic acid and an overview of the metal complex stereochemistries of the alkali metal salt series with this ligand.

4-Nitrobenzoic acid (PNBA) has proved to be a useful ligand for the preparation of metal complexes but the known structures of the alkali metal salts of PNBA do not include the rubidium salt. The structures of the isomorphous potassium and rubidium polymeric coordination complexes with PNBA, namely poly[μ2-aqua-aqua-μ3-(4-nitrobenzoato)-potassium], [K(C7H4N2O2)(H2O)2]n, (I), and poly[μ3-aqua-aqua-μ5-(4-nitrobenzoato)-rubidium], [Rb(C7H4N2O2)(H2O)2]n, (II), have been determined. In (I), the very distorted KO6 coordination sphere about the K(+) centres in the repeat unit comprise two bridging nitro O-atom donors, a single bridging carboxylate O-atom donor and two water molecules, one of which is bridging. In Rb complex (II), the same basic MO6 coordination is found in the repeat unit, but it is expanded to RbO9 through a slight increase in the accepted Rb-O bond-length range and includes an additional Rb-O(carboxylate) bond, completing a bidentate O,O'-chelate interaction, and additional bridging Rb-O(nitro) and Rb-O(water) bonds. The comparative K-O and Rb-O bond-length ranges are 2.7352 (14)-3.0051 (14) and 2.884 (2)-3.182 (2) Å, respectively. The structure of (II) is also isomorphous, as well as isostructural, with the known structure of the nine-coordinate caesium 4-nitrobenzoate analogue, (III), in which the Cs-O bond-length range is 3.047 (4)-3.338 (4) Å. In all three complexes, common basic polymeric extensions are found, including two different centrosymmetric bridging interactions through both water and nitro groups, as well as extensions along c through the para-related carboxylate group, giving a two-dimensional structure in (I). In (II) and (III), three-dimensional structures are generated through additional bridges involving the nitro and water O atoms. In all three structures, the two water molecules are involved in similar intra-polymer O-H...O hydrogen-bonding interactions to both carboxylate and water O-atom acceptors. A comparison of the varied coordination behaviour of the full set of Li-Cs salts with 4-nitrobenzoic acid is also made.

Ab initio kinetics and thermal decomposition mechanism of mononitrobiuret and 1,5-dinitrobiuret

Mononitrobiuret (MNB) and 1,5-dinitrobiuret (DNB) are tetrazole-free, nitrogen-rich, energetic compounds. For the first time, a comprehensive ab initio kinetics study on the thermal decomposition mechanisms of MNB and DNB is reported here. In particular, the intramolecular interactions of amine H-atom with electronegative nitro O-atom and carbonyl O-atom have been analyzed for biuret, MNB, and DNB at the M06-2X/aug-cc-pVTZ level of theory. The results show that the MNB and DNB molecules are stabilized through six-member-ring moieties via intramolecular H-bonding with interatomic distances between 1.8 and 2.0 Å, due to electrostatic as well as polarization and dispersion interactions. Furthermore, it was found that the stable molecules in the solid state have the smallest dipole moment amongst all the conformers in the nitrobiuret series of compounds, thus revealing a simple way for evaluating reactivity of fuel conformers. The potential energy surface for thermal decomposition of MNB was characterized by spin restricted coupled cluster theory at the RCCSD(T)/cc-pV∞ Z//M06-2X/aug-cc-pVTZ level. It was found that the thermal decomposition of MNB is initiated by the elimination of HNCO and HNN(O)OH intermediates. Intramolecular transfer of a H-atom, respectively, from the terminal NH2 group to the adjacent carbonyl O-atom via a six-member-ring transition state eliminates HNCO with an energy barrier of 35 kcal/mol and from the central NH group to the adjacent nitro O-atom eliminates HNN(O)OH with an energy barrier of 34 kcal/mol. Elimination of HNN(O)OH is also the primary process involved in the thermal decomposition of DNB, which processes C2v symmetry. The rate coefficients for the primary decomposition channels for MNB and DNB were quantified as functions of temperature and pressure. In addition, the thermal decomposition of HNN(O)OH was analyzed via Rice-Ramsperger-Kassel-Marcus/multi-well master equation simulations, the results of which reveal the formation of (NO2 + H2O) to be the major decomposition path. Furthermore, we provide fundamental interpretations for the experimental results of Klapötke et al. [Combust. Flame 139, 358-366 (2004)] regarding the thermal stability of MNB and DNB, and their decomposition products. Notably, a fundamental understanding of fuel stability, decomposition mechanism, and key reactions leading to ignition is essential in the design and manipulation of molecular systems for the development of new energetic materials for advanced propulsion applications.

Crystal structures of 2-(4-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one and 2-(2-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one.

The crystal structures are reported of the isomeric compounds 2-(4-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one, (I), and 2-(2-nitro-phen-yl)-3-phenyl-2,3-di-hydro-4H-1,3-benzo-thia-zin-4-one, (II), both C20H14N2O3S, being the para-nitro and ortho-nitro forms, respectively, the meta-form of which is known [Yennawar et al. (2013). Acta Cryst. E69, o1679]. The six-membered thia-zone ring fused with a benzene ring displays a screw-boat conformation with a total puckering amplitude of 0.627 (1) Å in (I), and a near screw-boat conformation with a total puckering amplitude of 0.600 (1) Å in (II). The dihedral angles between the planes of the substituent nitrophenyl and phenyl and rings with the benzene ring of the parent benzo-thia-zone moiety are 75.93 (5) and 82.61 (5)° [in (I)], and 76.79 (6) and 71.66 (6)° [in (II)]. Weak inter-molecular C-H⋯O hydrogen-bonding inter-actions between aromatic H-atom donors and both a nitro-O atom and a thia-zone O-atom acceptor in (I) and a thia-zone O atom in (II) are present, forming in (I) a centrosymmetric 22-membered cyclic dimer which is extended through a similar inversion-related 14-membered cyclic hydrogen-bonding association into a zigzag chain structure extending along c. In (II), a single inter-molecular C-H⋯O hydrogen bond gives a chain structure extending along b. In addition, weak C-H⋯π inter-actions are present in both structures [minimum C⋯ring-centroid separations = 3.630 (2) and 3.581 (2) Å, respectively].

Crystal structure of N,N-di-ethyl-benzene-1,4-diaminium dinitrate.

In the structure of the title mol­ecular salt, C10H18N2 2+·2NO3 −, the dinitrate salt of 4-(N,N-di­ethyl­amino)­aniline, the two ethyl groups lie almost perpendicular to the plane of the benzene ring [the ring-to-ethyl C—C—N—C torsion angles are −59.5 (2) and 67.5 (3)°]. The aminium groups of the cation form inter-species N—H⋯O hydrogen bonds with the nitro O-atom acceptors of both anions, giving rise to chain substructures lying along c. The chains are linked via further N—H⋯O hydrogen bonds, forming two-dimensional networks lying parallel to (010). These sheets are linked by C—H⋯O hydrogen bonds, forming a three-dimensional structure.

Crystal structures of the co-crystalline adduct 5-(4-bromo-phen-yl)-1,3,4-thia-diazol-2-amine-4-nitro-benzoic acid (1/1) and the salt 2-amino-5-(4-bromo-phen-yl)-1,3,4-thia-diazol-3-ium 2-carb-oxy-4,6-di-nitro-phenolate.

The structures of the 1:1 co-crystalline adduct C8H6BrN3S·C7H5NO4, (I), and the salt C8H7BrN3S(+)·C7H3N2O7 (-), (II), obtained from the inter-action of 5-(4-bromo-phen-yl)-1,3,4-thia-diazol-2-amine with 4-nitro-benzoic acid and 3,5-di-nitro-salicylic acid, respectively, have been determined. The primary inter-species association in both (I) and (II) is through duplex R (2) 2(8) (N-H⋯O/O-H⋯O) or (N-H⋯O/N-H⋯O) hydrogen bonds, respectively, giving heterodimers. In (II), these are close to planar [the dihedral angles between the thia-diazole ring and the two phenyl rings are 2.1 (3) (intra) and 9.8 (2)° (inter)], while in (I) these angles are 22.11 (15) and 26.08 (18)°, respectively. In the crystal of (I), the heterodimers are extended into a chain along b through an amine N-H⋯Nthia-diazole hydrogen bond but in (II), a centrosymmetric cyclic hetero-tetra-mer structure is generated through N-H⋯O hydrogen bonds to phenol and nitro O-atom acceptors and features, together with the primary R (2) 2(8) inter-action, conjoined R (4) 6(12), R (2) 1(6) and S(6) ring motifs. Also present in (I) are π-π inter-actions between thia-diazole rings [minimum ring-centroid separation = 3.4624 (16) Å], as well as short Br⋯Onitro inter-actions in both (I) and (II) [3.296 (3) and 3.104 (3) Å, respectively].

N,N,N'-Trimethyl-N''-(4-nitro-phen-yl)-N'-phenyl-guanidine.

The C—N bond lengths in the guanidine unit of the title compound, C16H18N4O2, are 1.298 (2), 1.353 (2) and 1.401 (3) Å, indicating double- and single-bond character. The N—C—N angles are 115.81 (16), 118.90 (18) and 125.16 (18)°, showing a deviation of the CN3 plane from an ideal trigonal–planar geometry. In the crystal, C—H⋯O hydrogen bonds are observed between the methyl- and aromatic-H atoms and nitro-O atoms. One H atom of the phenyl ring and of the NMe2 group associate with the O atoms of the nitro group, giving chains along the a- and b-axis directions. Cross-linking of these two chains results in a two-dimensional network along bc.

Hydrogen-bonded two- and three-dimensional polymeric structures in the ammonium salts of 3,5-dinitrobenzoic acid, 4-nitrobenzoic acid and 2,4-dichlorobenzoic acid

The structures of ammonium 3,5-dinitrobenzoate, NH4(+) · C7H3N2O6(-), (I), ammonium 4-nitrobenzoate dihydrate, NH4(+) · C7H4NO4(-) · 2H2O, (II), and ammonium 2,4-dichlorobenzoate hemihydrate, NH4(+) · C7H3Cl2O2(-) · 0.5H2O, (III), have been determined and their hydrogen-bonded structures are described. All three salts form hydrogen-bonded polymeric structures, viz. three-dimensional in (I) and two-dimensional in (II) and (III). With (I), a primary cation-anion cyclic association is formed [graph set R4(3)(10)] through N-H...O hydrogen bonds, involving a carboxylate group with both O atoms contributing to the hydrogen bonds (denoted O,O'-carboxylate) on one side and a carboxylate group with one O atom involved in two hydrogen bonds (denoted O-carboxylate) on the other. Structure extension involves N-H...O hydrogen bonds to both carboxylate and nitro O-atom acceptors. With structure (II), the primary inter-species interactions and structure extension into layers lying parallel to (001) are through conjoined cyclic hydrogen-bonding motifs, viz. R4(3)(10) (one cation, an O,O'-carboxylate group and two water molecules) and centrosymmetric R4(2)(8) (two cations and two water molecules). The structure of (III) also has conjoined R4(3)(10) and centrosymmetric R4(2)(8) motifs in the layered structure but these differ in that the first motif involves one cation, an O,O'-carboxylate group, an O-carboxylate group and one water molecule, and the second motif involves two cations and two O-carboxylate groups. The layers lie parallel to (100). The structures of salt hydrates (II) and (III), displaying two-dimensional layered arrays through conjoined hydrogen-bonded nets, provide further illustration of a previously indicated trend among ammonium salts of carboxylic acids, but the anhydrous three-dimensional structure of (I) is inconsistent with that trend.

Poly[μ3-aqua-aqua-μ5-(4-nitrobenzoato)-caesium

In the structure of the title complex, [Cs(C7H4NO2)(H2O)2]n, the caesium salt of 4-nitro­benzoic acid, the irregular CsO9 coordination sphere comprises three bridging nitro O-atom donors, a bidentate carboxyl­ate O,O′-chelate inter­action, a triple-bridging water mol­ecule and a monodentate water mol­ecule. A three-dimensional framework polymer is generated, within which there are water–carboxyl­ate O—H⋯O and water–water O—H⋯O hydrogen-bonding inter­actions.

Proton-Transfer and Non-transfer Compounds of the Multi-purpose Drug Dapsone [4-(4-Aminophenylsulfonyl)aniline] with 3,5-Dinitrosalicylic Acid and 5-Nitroisophthalic Acid

The structures of the compounds from the reaction of the drug dapsone [4-(4-aminophenylsulfonyl)aniline] with 3,5-dinitrosalicylic acid, the salt hydrate [4-(4-aminophenylsulfonyl)anilinium 2-carboxy-4,6-dinitrophenolate monohydrate] (1) and the 1:1 adduct with 5-nitroisophthalic acid [4-(4-aminophenylsulfonyl)aniline 5-nitrobenzene-1,3-dicarboxylic acid] (2) have been determined. Crystals of 1 are triclinic, space group P-1, with unit cell dimensions a = 8.2043(3), b = 11.4000(6), c = 11.8261(6) Å, α = 110.891(5)°, β = 91.927(3)°, γ = 98.590(4)° and Z = 4. Compound 2 is orthorhombic, space group Pbcn, with unit cell dimensions a = 20.2662(6), b = 12.7161(4), c = 15.9423(5) Å and Z = 8. In 1, intermolecular analinium N–H···O and water O–H···O and O–H···N hydrogen-bonding interactions with sulfone, carboxyl, phenolate and nitro O-atom and aniline N-atom acceptors give a two-dimensional layered structure. With 2, the intermolecular interactions involve both aniline N–H···O and carboxylic acid O–H···O and O–H···N hydrogen bonds to sulfone, carboxyl, nitro and aniline acceptors, giving a three-dimensional network structure. In both structures π–π aromatic ring associations are present. The structures of both an uncommon proton-transfer salt of the drug dapsone with 3,5-dinitrosalicylic acid and a molecular adduct with 5-nitroisophthalic acid are reported, together with their hydrogen-bonding patterns.

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).

4-(4-Aminophenylsulfonyl)aniline–1,3,5-trinitrobenzene (1/2)

The asymmetric unit of the title co-crystalline 1:2 adduct, C12H12N2O2·2C6H3N3O6, contains two independent mol­ecules of bis­(4-amino­phen­yl) sulfone (the drug Dapsone) and four mol­ecules of 1,3,5-trinitro­benzene and is extended into a two-dimensional hydrogen-bonded network structure through amino N—H⋯O hydrogen-bonding associations with nitro O-atom acceptors. In the two independent Dapsone mol­ecules, the inter-ring dihedral anges are 69.6 (3) and 63.63 (9)°. Aromatic π–π inter­actions are also found between one of the Dapsone aromatic rings and a trinitro­benzene ring [minimum ring centroid separation = 3.596 (3) Å]. A 4-amino­phenyl ring moiety of one of the Dapsone mol­ecules and two nitro groups of a trinitro­benzene are disordered in a 50:50 ratio.

Poly[tetra-μ-aqua-diaquatetrakis[μ-(E)-2-nitrocinnamato]tetrarubidium

In the structure of the title compound, [Rb4(C9H6NO4)4(H2O)6]n, the asymmetric unit comprises four rubidium cations, two of which have an RbO7 coordination polyhedron with a monocapped distorted octa­hedral stereochemistry and two of which have a distorted RbO6 octa­hedral coordination. The bonding about both the seven-coordinate cations is similar, comprising one monodentate water mol­ecule together with three bridging water mol­ecules and three carboxyl­ate O-atom donors, two of which are bridging. The environments around the six-coordinate cations are also similar, comprising a monodentate nitro O-atom donor, a bridging water mol­ecule and four bridging carboxyl­ate O-atom donors [overall Rb—O range = 2.849 (2)–3.190 (2) Å]. The coordination leads to a two-dimensional polymeric structure extending parallel to (001), which is stabilized by inter­layer water O—H⋯O hydrogen-bonding associations to water, carboxyl and nitro O-atom acceptors, together with weak inter-ring π–π inter­actions [minimum ring centroid–centroid separation = 3.5319 (19) Å].