Dipotassium aqua­penta­fluoro­vanadate

The title compound, K₂[VF₅(H₂O)], was synthesized from potassium antimony tartrate, piperazine, V₂O₅ and HF under hydro­thermal conditions. It is isostructural with K₂[FeF₅(H₂O)] and contains polymeric anion chains held together by strong O—H⋯F bonds. Each V atom is coordinated to five terminal F atoms and the O atom of one water mol­ecule. Pairs of O—H⋯F bonds are formed by two cis‐related F atoms. Twofold axes run along the O—V—F axis of the V‐centred otahedra.     

The challenging case of the theophylline–benzamide cocrystal

Theophylline has been used as an active pharmaceutical ingredient (API) in the treatment of pulmonary diseases, but due to its low water solubility reveals very poor bioavailability. Based on its different hydrogen‐bond donor and acceptor groups, theophylline is an ideal candidate for the formation of cocrystals. The crystal structure of the 1:1 benzamide cocrystal of theophylline, C₇H₈N₄O₂·C₇H₇NO, was determined from synchrotron X‐ray powder diffraction data. The compound crystallizes in the tetragonal space group P4₁ with four independent molecules in the asymmetric unit. The molecules form a hunter's fence packing. The crystal structure was confirmed by dispersion‐corrected DFT calculations. The possibility of salt formation was excluded by the results of Raman and ¹H solid‐state NMR spectroscopic analyses.     

The cocrystal nicotinamide–succinic acid (2/1)

In the asymmetric unit of the crystal structure of nicotinamide–succinic acid (2/1), 2C₆H₆N₂O·C₄H₆O₄, there are two independent nicotinamide molecules in general positions and two half succinic acid molecules which lie about inversion centres. The structure contains acid–pyridine and amide–amide synthons with nicotinamide molecules forming ladders of alternating R₂²(8) and R₄²(8) rings linked through succinic acid to generate a corrugated hydrogen‐bonded sheet. This sheet is a common supramolecular unit found in other 2:1 nicotinamide–dicarboxylic acid cocrystals, but the presence of two crystallographically distinct nicotinamides with anti and syn conformations, forming two distinct sheets within the same structure, is a novel packing feature in this type of material.     

A 1:1 cocrystal of fluconazole with salicylic acid

The interaction of the antifungal pharmaceutical agent fluconazole with salicylic acid in acetonitrile solution yields the 1:1 cocrystal 2‐(2,4‐difluorophenyl)‐1,3‐bis(1H‐1,2,4‐triazol‐1‐yl)propan‐2‐ol–2‐hydroxybenzoic acid (1/1), C₁₃H₁₂F₂N₆O·C₇H₆O₃. The asymmetric unit consists of one molecule of fluconazole and one molecule of salicylic acid, both in their neutral forms. Both crystal agents form head‐to‐tail hydrogen‐bonded dimers, which are further connected into hydrogen‐bonded extended zigzag tapes propagating along the ac diagonal.     

Pyridine mediated supramolecular assemblies of 3,5-dinitro substituted benzoic acid, benzamide and benzonitrile

Synthesis and characterization of molecular assemblies of pyridine adducts, 1a, 2a and 3a, of 3,5-dinitrobenzoic acid, 1, 3,5-dinitrobenzamide, 2 and 3,5-dinitrobenzonitrile, 3, respectively, have been reported. All these adducts were obtained by crystallization of 1, 2 and 3 from pyridine. However, crystallization of 1 from pyridine in the presence of benzene resulted in the formation of a pyridinium adduct, 1b, along with a water molecule. All the adducts crystallize in a 1:1 molecular ratio except 1a, which forms a 1:2 adduct, as characterized by single crystal X-ray diffraction method. The adducts crystallize in different space groups—1a, orthorhombic, Pna2₁; 1b, monoclinic, P2₁; 2a, monoclinc, C2/c; 3a, triclinic, . In two-dimensional arrangement, 1a, 1b and 3a form sheet structures. In 1a, within the two-dimensional sheets, large cavities are formed, which are occupied by pyridine molecules. In 1b, the sheets are catenated to form a chicken-wire network. However, 2a formed a crossed ribbon packing pattern with empty channels in the three-dimensional structure.     

2:1 Complexes of 2‐chloro‐4‐nitro­benzoic acid and 2‐chloro‐5‐nitro­benzoic acid with pyrazine

2‐Chloro‐4‐nitro­benzoic acid and 2‐chloro‐5‐nitro­benzoic acid form O—H?N hydrogen bonds with pyrazine to afford 2:1 complexes of 2C₇H₄ClNO₄·C₄H₄N₂, (I) and (II), respectively, that are located on inversion centers. The 2C₇H₄ClNO₄·­C₄H₄N₂ units in both complexes are connected by weak C—H?O hydrogen bonds; the units build a three‐dimensional hydrogen‐bond network in (I) and a ribbon structure in (II).     

Di­methyl(2‐methyl­phenyl)­ammonium hydroxo­tris­(penta­fluoro­phenyl)­borate

In the title compound, [(CH₃)₂(C₇H₇)NH][(C₆F₅)₃B(OH)] or C₉H₁₄N⁺·C₁₈HBF₁₅O^?, the distorted tetrahedral borate anions are strongly hydrogen bonded to the substituted ammonium cations. The N?O separation in the N—H?O hydrogen bond is 2.728 (3) Å.     

2-(1H-Tetrazol-1-yl)­benzoic acid

In the title compound, C₈H₆N₄O₂, the tetrazole and benzene rings are planar to within 0.001 (1) and 0.007 (1) Å, respectively. These rings are not coplanar in the mol­ecule, the dihedral angle between them being 52.90 (4)°. Molecules are connected together by O—H⋯N and C—H⋯O hydrogen bonds, forming two-dimensional networks parallel to the xz plane with van der Waals interactions between them.     

The bis(η5‐cyclo­penta­dienyl)­methyl­zirconium(IV) methyl­tris­(penta­fluoro­phenyl)­borate ion pair

The title complex, [Zr(CH₃)(C₅H₅)₂][CH₃B(C₆F₅)₃], crystallizes as an ion pair linked through an unsymmetrical methyl bridge. The bridging Zr—Me distance [2.556 (2) Å] is significantly longer than the terminal Zr—Me distance [2.251 (3) Å], while the Zr—C—B angle approaches linearity [169.1 (2)°].     

Crystal structures of the pyrazinamide–p‐aminobenzoic acid (1/1) cocrystal and the transamidation reaction product 4‐(pyrazine‐2‐carboxamido)benzoic acid in the molten state

The synthesis of pharmaceutical cocrystals is a strategy to enhance the performance of active pharmaceutical ingredients (APIs) without affecting their therapeutic efficiency. The 1:1 pharmaceutical cocrystal of the antituberculosis drug pyrazinamide (PZA) and the cocrystal former p‐aminobenzoic acid (p‐ABA), C₇H₇NO₂·C₅H₅N₃O, (1), was synthesized successfully and characterized by relevant solid‐state characterization methods. The cocrystal crystallizes in the monoclinic space group P2₁/n containing one molecule of each component. Both molecules associate via intermolecular O—H...O and N—H...O hydrogen bonds [O...O = 2.6102 (15) Å and O—H...O = 168.3 (19)°; N...O = 2.9259 (18) Å and N—H...O = 167.7 (16)°] to generate a dimeric acid–amide synthon. Neighbouring dimers are linked centrosymmetrically through N—H...O interactions [N...O = 3.1201 (18) Å and N—H...O = 136.9 (14)°] to form a tetrameric assembly supplemented by C—H...N interactions [C...N = 3.5277 (19) Å and C—H...N = 147°]. Linking of these tetrameric assemblies through N—H...O [N...O = 3.3026 (19) Å and N—H...O = 143.1 (17)°], N—H...N [N...N = 3.221 (2) Å and N—H...N = 177.9 (17)°] and C—H...O [C...O = 3.5354 (18) Å and C—H...O = 152°] interactions creates the two‐dimensional packing. Recrystallization of the cocrystals from the molten state revealed the formation of 4‐(pyrazine‐2‐carboxamido)benzoic acid, C₁₂H₉N₃O₃, (2), through a transamidation reaction between PZA and p‐ABA. Carboxamide (2) crystallizes in the triclinic space group P with one molecule in the asymmetric unit. Molecules of (2) form a centrosymmetric dimeric homosynthon through an acid–acid O—H...O hydrogen bond [O...O = 2.666 (3) Å and O—H...O = 178 (4)°]. Neighbouring assemblies are connected centrosymmetrically via a C—H...N interaction [C...N = 3.365 (3) Å and C—H...N = 142°] engaging the pyrazine groups to generate a linear chain. Adjacent chains are connected loosely via C—H...O interactions [C...O = 3.212 (3) Å and C—H...O = 149°] to generate a two‐dimensional sheet structure. Closely associated two‐dimensional sheets in both compounds are stacked via aromatic π‐stacking interactions engaging the pyrazine and benzene rings to create a three‐dimensional multi‐stack structure.     

Bis­(iso­propyl­amino)­methyl­carbenium tetrakis­(penta­fluoro­phenyl)­gallate

The title compound, [MeC(NHⁱPr)₂][Ga(C₆F₅)₄] crystallizes as discrete ions forming interionic hydrogen bonds of the type N—H?F.     

Hydrogen‐bonded layers in the 1:2 cocrystal of 2,2′‐dithiodibenzoic acid with isonicotinohydrazide

Cocrystallization of 2,2′‐dithiodibenzoic acid with isonicotinohydrazide from methanol solution yields the 1:2 cocrystal 2,2′‐dithiodibenzoic acid–isonicotinohydrazide (1/2), C₁₄H₁₀O₄S₂·2C₆H₇N₃O. The component molecules are linked by intermolecular O—H...N, N—H...O, N—H...N and C—H...O hydrogen bonds into layers running parallel to the (010) plane, and these layers are further linked into a three‐dimensional framework structure by means of weak aromatic π–π stacking interactions. As a potential cocrystallization agent, isonicotinohydrazide may be used for effective and versatile synthetic supramolecular strategies utilizing hydrogen bonding of specific molecular building blocks.     

Probenecid and benzamide: cocrystal prepared by a green method and its physico-chemical and pharmaceutical characterization

Journal of Thermal Analysis and Calorimetry - The eco-friendly method of kneading was here used to synthesize a cocrystal of probenecid, an uricosuric drug used in treating gout and hyperuricemia,...     

[5,10,15,20‐Tetrakis­(penta­fluoro­phenyl)­porphyrinato]­iron(II) benzene disolvate

The title compound, [Fe(C₄₄H₈F₂₀N₄)]·2C₆H₆, contains a four‐coordinated Fe^II atom, which lies on a center of symmetry. The porphyrin macrocycle is planar, and the Fe—N bond distances are in the range 1.9891 (13)–1.9982 (13) Å. The spin state of the Fe^II atom is intermediate (S = 1), as confirmed by NMR spectroscopy. The asymmetric unit contains two half benzene mol­ecules, each lying about an independent inversion centre; one of the benzene rings is located just below (and by inversion symmetry, another is just above) the Fe atom, where it interacts weakly with the porphyrin ring.     

A 2:1 sulfamethazine–theophylline cocrystal exhibiting two tautomers of sulfamethazine

In the title cocrystal, 4‐amino‐N‐(4,6‐dimethylpyrimidin‐2‐yl)benzenesulfonamide–4‐amino‐N‐(4,6‐dimethyl‐1,2‐dihydropyrimidin‐2‐ylidene)benzenesulfonamide–1,3‐dimethyl‐7H‐purine‐2,6‐dione (1/1/1), C₇H₈N₄O₂·2C₁₂H₁₄N₄O₂S, two sulfamethazine molecules cocrystallize with a single molecule of theophylline. Each molecule of sulfamethazine forms a hydrogen‐bonded ribbon along the b axis crosslinked by further hydrogen bonding. The two sulfamethazine molecules exhibit a hydrogen‐shift isomerization so that the crystal structure contains both tautomeric forms. Calculation of their relative energies showed that the tautomer protonated at the chain N atom is considerably more stable than the one where an N atom in the aromatic ring is protonated. The latter, here observed for the first time, is stabilized through strong intermolecular interactions with the theophylline molecules.     

Azido­[1,1′‐bis­(di­phenyl­phosphino)­ferrocene](penta­methyl­cyclo­penta­dienyl)­rhodium(III) hexa­fluoro­phosphate

In the title compound, azido‐2κN‐bis­[μ‐(1η⁵:2κP)‐di­phenyl­phosphino­cyclo­penta­dienyl][2(η⁵)‐penta­methyl­cyclo­penta­di­enyl]­iron(III)­rhodium(III) hexa­fluoro­phosphate, [{Rh(C₁₀H₁₅)(N₃)}{Fe(μ‐C₁₇H₁₄P)₂}]PF₆ or [FeRh(C₁₀H₁₅)(μ‐C₁₇H₁₄P)₂(N₃)]PF₆, the coordination sphere of Rh^III can be described as pseudo‐tetrahedral, composed of two P atoms from a 1,1′‐bis­(di­phenyl­phosphino)­ferrocene (dppf) ligand, an azido N atom and the centroid of the ring of a C₅Me₅ (Cp*) ligand. The two cyclo­penta­dienyl rings in the dppf moiety adopt an eclipsed conformation. The Rh⋯Fe distance is 4.340 (2) Å.