Supramolecular sheets in (4H‐chromeno[4,3‐c]isoxazol‐3‐yl)methanol and its hydrated 8‐methyl‐substituted analogue at 100 K

The title compounds, (4H‐chromeno[4,3‐c]isoxazol‐3‐yl)methanol, C₁₁H₉NO₃, (I), and (8‐methyl‐4H‐chromeno[4,3‐c]isoxazol‐3‐yl)methanol monohydrate, C₁₂H₁₁NO₃·H₂O, (II), crystallize in the monoclinic space groups P2₁/c and C2/c, respectively. The simple addition of a methyl substituent in (II) results in a change in the structure type and substantially alters the intermolecular interaction patterns, while retaining the point‐group symmetry 2/m. Compound (II) crystallizes as a hydrate and the resulting hydrogen‐bonding interactions involving the water molecule are the cause of differences in the hydrogen‐bonded supramolecular motifs present in (I) and (II). The water molecule in (II) is disordered over two positions having very similar orientations, with occupancies of 0.571 (18) and 0.429 (18), although the pattern of hydrogen‐bonding interactions for the two disordered water molecules remains essentially the same. In both compounds, the primary donor hydroxy group adopts a trans conformation with respect to the isoxazole O atom, with a torsion angle of 170.65 (8)° for (I) and 179.56 (10)° for (II), the small difference being due to differences in the hydrogen‐bonding environment of the hydroxy group. In (I), molecules are linked through two independent O—H...N and C—H...O hydrogen bonds and form sheets of centrosymmetric R₄⁴(18) and R₄⁴(14) rings extending parallel to the (100) plane. The supramolecular motifs in (II) generate two‐dimensional sheets parallel to the (100) plane through a combination of O—H...X (X = N, O) and C—H...O hydrogen bonds, leading to water‐assisted noncentrosymmetric R₂²(8) and R₆⁶(20) motifs. The present work is an example of how the simple replacement of a substituent in the main molecular scaffold may transform the structure type, paving the way for a variety of supramolecular motifs and consequently altering the complexity of the intermolecular interaction patterns.     

2‐{[(3‐Fluorophenyl)amino]methylidene}‐3‐oxobutanenitrile and 5‐{[(3‐fluorophenyl)amino]methylidene}‐2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione: X‐ray and DFT studies

In the crystal structures of the title compounds, C₁₁H₉FN₂O, (I), and C₁₃H₁₂FNO₄, (II), the molecules are joined pairwise via different hydrogen bonds and the constituent pairs are crosslinked by weak C—H...O hydrogen bonds. The basic structural motif in (I), which is partially disordered, comprises pairs of molecules arranged in an antiparallel fashion which enables C—H...N[triple‐bond]C interactions. The pairs of molecules are crosslinked by two weak C—H...O hydrogen bonds. The constituent pair in (II) is formed by intramolecular bifurcated C—H...O/O′ and combined inter‐ and intramolecular N—H...O hydrogen bonds. In both structures, F atoms form weak C—F...H—C interactions with the H atoms of the two neighbouring methyl groups, the H...F separations being 2.59/2.80 and 2.63/2.71 Å in (I) and (II), respectively. The bond orders in the molecules, estimated using the natural bond orbitals (NBO) formalism, correlate with the changes in bond lengths. Deviations from the ideal molecular geometry are explained by the concept of non‐equivalent hybrid orbitals. The existence of possible conformers of (I) and (II) is analysed by molecular calculations at the B3LYP/6–31+G** level of theory.     

Assembling an isomer grid: the isomorphous 4‐, 3‐ and 2‐fluoro‐N′‐(4‐pyridyl)benzamides

The three title isomers, 4‐, (I), 3‐, (II), and 2‐fluoro‐N′‐(4‐pyridyl)benzamide, (III), all C₁₂H₉FN₂O, crystallize in the P2₁/c space group (No. 14) with similar unit‐cell parameters and are isomorphous and isostructural at the primary hydrogen‐bonding level. An intramolecular C—H...O=C interaction is present in all three isomers [C...O = 2.8681 (17)–2.884 (2) Å and C—H...O117–118°], with an additional N—H...F [N...F = 2.7544 (15) Å] interaction in (III). Intermolecular amide–pyridine N—H...N hydrogen bonds link molecules into one‐dimensional zigzag chains [graph set C(6)] along the [010] direction as the primary hydrogen bond [N...N = 3.022 (2), 3.049 (2) and 3.0213 (17) Å]. These are augmented in (I) by C—H...π(arene) and cyclic C—F...π(arene) contacts about inversion centres, in (II) by C—F...F—C interactions [C...F = 3.037 (2) Å] and weaker C—H...π(arene)/C—H...F contacts, and in (III) by C—H...π(arene) and C=O...O=C interactions, linking the alternating chains into two‐dimensional sheets. Typical amide N—H...O=C hydrogen bonds [as C(4) chains] are not present [N...O = 3.438 (2) Å in (I), 3.562 (2) Å in (II) and 3.7854 (16) Å in (III)]; the C=O group is effectively shielded and only participates in weaker interactions/contacts. This series is unusual as the three isomers are isomorphous (having similar unit‐cell parameters, packing and alignment), but they differ in their interactions and contacts at the secondary level.     

Three different fluoro‐ or chloro‐substituted 1′‐deoxy‐1′‐phenyl‐β‐D‐ribofuranoses

Crystal structures are reported for three fluoro‐ or chloro‐substituted 1′‐deoxy‐1′‐phenyl‐β‐D‐ribofuranoses, namely 1′‐deoxy‐1′‐(2,4,5‐trifluorophenyl)‐β‐D‐ribofuranose, C₁₁H₁₁F₃O₄, (I), 1′‐deoxy‐1′‐(2,4,6‐trifluorophenyl)‐β‐D‐ribofuranose, C₁₁H₁₁F₃O₄, (II), and 1′‐(4‐chlorophenyl)‐1′‐deoxy‐β‐D‐ribofuranose, C₁₁H₁₃ClO₄, (III). The five‐membered furanose ring of the three compounds has a conformation between a C2′‐endo,C3′‐exo twist and a C2′‐endo envelope. The ribofuranose groups of (I) and (III) are connected by intermolecular O—H...O hydrogen bonds to six symmetry‐related molecules to form double layers, while the ribofuranose group of (II) is connected by O—H...O hydrogen bonds to four symmetry‐related molecules to form single layers. The O...O contact distance of the O—H...O hydrogen bonds ranges from 2.7172 (15) to 2.8895 (19) Å. Neighbouring double layers of (I) are connected by a very weak intermolecular C—F...π contact. The layers of (II) are connected by one C—H...O and two C—H...F contacts, while the double layers of (III) are connected by a C—H...Cl contact. The conformations of the molecules are compared with those of seven related molecules. The orientation of the benzene ring is coplanar with the H—C1′ bond or bisecting the H—C1′—C2′ angle, or intermediate between these positions. The orientation of the benzene ring is independent of the substitution pattern of the ring and depends mainly on crystal‐packing effects.     

Two different modes of halogen bonding in two 4‐nitroimidazole derivatives

In the crystal structures of the two imidazole derivatives 5‐chloro‐1,2‐dimethyl‐4‐nitro‐1H‐imidazole, C₅H₆ClN₃O₂, (I), and 2‐chloro‐1‐methyl‐4‐nitro‐1H‐imidazole, C₄H₄ClN₃O₂, (II), C—Cl...O halogen bonds are the principal specific interactions responsible for the crystal packing. Two different halogen‐bond modes are observed: in (I), there is one very short and directional C—Cl...O contact [Cl...O = 2.899 (1) Å], while in (II), the C—Cl group approaches two different O atoms from two different molecules, and the contacts are longer [3.285 (2) and 3.498 (2) Å] and less directional. In (I), relatively short C—H...O hydrogen bonds provide the secondary interactions for building the crystal structure; in (II), the C—H...O contacts are longer but there is a relatively short π–π contact between molecules related by a centre of symmetry. The molecule of (I) is almost planar, the plane of the nitro group making a dihedral angle of 6.97 (7)° with the mean plane of the imidazole ring. The molecule of (II) has crystallographically imposed mirror symmetry and the nitro group lies in the mirror plane.     

Similarities and differences in the structures of 5‐bromo‐6‐hydroxy‐7,8‐dimethylchroman‐2‐one and 6‐hydroxy‐7,8‐dimethyl‐5‐nitrochroman‐2‐one

The title compounds, C₁₁H₁₁BrO₃, (I), and C₁₁H₁₁NO₅, (II), respectively, are derivatives of 6‐hydroxy‐5,7,8‐trimethylchroman‐2‐one substituted at the 5‐position by a Br atom in (I) and by a nitro group in (II). The pyranone rings in both molecules adopt half‐chair conformations, and intramolecular O—H...Br [in (I)] and O—H...O_nitro [in (II)] hydrogen bonds affect the dispositions of the hydroxy groups. Classical intermolecular O—H...O hydrogen bonds are found in both molecules but play quite dissimilar roles in the crystal structures. In (I), O—H...O hydrogen bonds form zigzag C(9) chains of molecules along the a axis. Because of the tetragonal symmetry, similar chains also form along b. In (II), however, similar contacts involving an O atom of the nitro group form inversion dimers and generate R₂²(12) rings. These also result in a close intermolecular O...O contact of 2.686 (4) Å. For (I), four additional C—H...O hydrogen bonds combine with π–π stacking interactions between the benzene rings to build an extensive three‐dimensional network with molecules stacked along the c axis. The packing in (II) is much simpler and centres on the inversion dimers formed through O—H...O contacts. These dimers are stacked through additional C—H...O hydrogen bonds, and further weak C—H...O interactions generate a three‐dimensional network of dimer stacks.     

2‐Ethyl‐6‐methylpyridin‐3‐ol and its salt bis(2‐ethyl‐3‐hydroxy‐6‐methylpyridinium) succinate

The title compounds, C₈H₁₁NO, (I), and 2C₈H₁₂NO⁺·C₄H₄O₄²⁻, (II), both crystallize in the monoclinic space group P2₁/c. In the crystal structure of (I), intermolecular O—H...N hydrogen bonds combine the molecules into polymeric chains extending along the c axis. The chains are linked by C—H...π interactions between the methylene H atoms and the pyridine rings into polymeric layers parallel to the ac plane. In the crystal structure of (II), the succinate anion lies on an inversion centre. Its carboxylate groups interact with the 2‐ethyl‐3‐hydroxy‐6‐methylpyridinium cations via intermolecular N—H...O hydrogen bonds with the pyridine ring H atoms and O—H...O hydrogen bonds with the hydroxy H atoms to form polymeric chains, which extend along the [01] direction and comprise R₄⁴(18) hydrogen‐bonded ring motifs. These chains are linked to form a three‐dimensional network through nonclassical C—H...O hydrogen bonds between the pyridine ring H atoms and the hydroxy‐group O atoms of neighbouring cations. π–π interactions between the pyridine rings and C—H...π interactions between the methylene H atoms of the succinate anion and the pyridine rings are also present in this network.     

5:1 and 2:1 cocrystals of 2,3,4,5,6‐pentafluorophenol with phenazine

2,3,4,5,6‐Pentafluorophenol (pFp), unlike phenol, forms cocrystals with the weak heteroaromatic base phenazine (phz). Two types of cocrystals were prepared, (I) with a high content of pFp, 2,3,4,5,6‐pentafluorophenol–phenazine (5/1), 5C₆HF₅O·C₁₂H₈N₂, and (II) with a 2:1 pFp–phz molar ratio, 2,3,4,5,6‐pentafluorophenol–phenazine (2/1), 2C₆HF₅O·C₁₂H₈N₂. In both forms, homostacks are formed by the heterocyclic base and phenol molecules and no aryl–perfluoroaryl stacking interactions occur. The arrangement of the molecules in the crystal of (I) is determined by strong O—H...N and O—H...O hydrogen bonds, weak O—H...F, C—H...F and C—H...O interactions, π–π stacking interactions between the phz molecules and C—F...π_F interactions within the pFp stacks. Among the specific interactions in (II) are a strong O—H...N hydrogen bond, weak C—H...F interactions and π–π stacking interactions between the phz molecules. In (I) and (II), the heterocyclic molecules are located around inversion centres and one of the symmetry‐independent pFp molecules in (I) is disordered about an inversion centre. Remarkably, similar structural fragments consisting of six pFp stacks can be identified in cocrystal (I) and in the known orthorhombic polymorph of pFp with Z′ = 3 [Gdaniec (2007). CrystEngComm, 9 , 286–288].     

9,10‐Di­phenyl‐9,10‐epi­dioxy­anthra­cene and 9,10‐di­hydro‐10,10‐di­methoxy‐9‐phenyl­anthracen‐9‐ol

9,10‐Di­phenyl‐9,10‐epi­dioxy­anthracene, C₂₆H₁₈O₂, (I), was accidentally used in a photo­oxy­genation reaction that produced 9,10‐di­hydro‐10,10‐di­methoxy‐9‐phenyl­anthracen‐9‐ol, C₂₂H₂₀O₃, (II). In both compounds, the phenyl rings are approximately orthogonal to the anthracene moiety. The conformation of the anthracene moiety differs as a result of substitution. Intramolecular C—H⃛O interactions in (I) form two approximately planar S(5) rings in each of the two crystallographically independent mol­ecules. The packing of (I) and (II) consists of molecular dimers stabilized by C—H⃛O interactions and of molecular chains stabilized by O—H⃛O interactions, respectively.     

A structural systematic study of three isomers of difluoro‐N‐(4‐pyridyl)benzamide

The isomers 2,3‐, (I), 2,4‐, (II), and 2,5‐difluoro‐N‐(4‐pyridyl)benzamide, (III), all with formula C₁₂H₈F₂N₂O, all exhibit intramolecular C—H...O=C and N—H...F contacts [both with S(6) motifs]. In (I), intermolecular N—H...O=C interactions form one‐dimensional chains along [010] [N...O = 3.0181 (16) Å], with weaker C—H...N interactions linking the chains into sheets parallel to the [001] plane, further linked into pairs via C—H...F contacts about inversion centres; a three‐dimensional herring‐bone network forms via C—H...π(py) (py is pyridyl) interactions. In (II), weak aromatic C—H...N(py) interactions form one‐dimensional zigzag chains along [001]; no other interactions with H...N/O/F < 2.50 Å are present, apart from long N/C—H...O=C and C—H...F contacts. In (III), N—H...N(py) interactions form one‐dimensional zigzag chains [as C(6) chains] along [010] augmented by a myriad of weak C—H...π(arene) and O=C...O=C interactions and C—H...O/N/F contacts. Compound (III) is isomorphous with the parent N‐(4‐pyridyl)benzamide [Noveron, Lah, Del Sesto, Arif, Miller & Stang (2002). J. Am. Chem. Soc. 124 , 6613–6625] and the three 2/3/4‐fluoro‐N‐(4‐pyridyl)benzamides [Donnelly, Gallagher & Lough (2008). Acta Cryst. C 64 , o335–o340]. The study expands our series of fluoro(pyridyl)benzamides and augments our understanding of the competition between strong hydrogen‐bond formation and weaker influences on crystal packing.     

Hydrogen‐bonded sheet structures in methyl 4‐(4‐chloroanilino)‐3‐nitrobenzoate and methyl 1‐benzyl‐2‐(4‐chlorophenyl)‐1H‐benzimidazole‐5‐carboxylate

In methyl 4‐(4‐chloroanilino)‐3‐nitrobenzoate, C₁₄H₁₁ClN₂O₄, (I), there is an intramolecular N—H...O hydrogen bond and the intramolecular distances provide evidence for electronic polarization of the o‐quinonoid type. The molecules are linked into sheets built from N—H...O, C—H...O and C—H...π(arene) hydrogen bonds, together with an aromatic π–π stacking interaction. The molecules of methyl 1‐benzyl‐2‐(4‐chlorophenyl)‐1H‐benzimidazole‐5‐carboxylate, C₂₂H₁₇ClN₂O₂, (II), are also linked into sheets, this time by a combination of C—H...π(arene) hydrogen bonds and aromatic π–π stacking interactions.     

Hydrogen‐bonded and π‐interaction assembly in two 8‐alkoxycarbonyl‐1,8‐diazabicyclo[5.4.0]undec‐7‐enium chloride salts

The crystal structures of 8‐phenoxycarbonyl‐1,8‐diazabicyclo[5.4.0]undec‐7‐enium chloride, C₁₆H₂₁N₂O₂⁺·Cl⁻, (I), and 8‐methoxycarbonyl‐1,8‐diazabicyclo[5.4.0]undec‐7‐enium chloride monohydrate, C₁₁H₁₉N₂O₂⁺·Cl⁻·H₂O, (II), recently reported by Carafa, Mesto & Quaranta [Eur. J. Org. Chem. (2011), pp. 2458–2465], are analysed and discussed with a focus on crystal interaction assembly. Both compounds crystallize in the space group P2₁/c. The crystal packings are characterized by dimers linked through π–π stacking interactions and intermolecular nonclassical hydrogen bonds, respectively. Additional intermolecular C—H...Cl interactions [in (I) and (II)] and classical O—H...Cl hydrogen bonds [in (II)] are also evident and contribute to generating three‐dimensional hydrogen‐bonded networks.     

Positional isomeric effect on the crystallization of chlorine‐substituted N‐phenyl‐2‐phthalimidoethanesulfonamide derivatives

The ortho‐, para‐ and meta‐chloro‐substituted N‐chlorophenyl‐2‐phthalimidoethanesulfonamide derivatives, C₁₆H₁₃ClN₂O₄S, have been structurally characterized by single‐crystal X‐ray crystallography. N‐(2‐Chlorophenyl)‐2‐phthalimidoethanesulfonamide, (I), has orthorhombic (P2₁2₁2₁) symmetry, N‐(4‐chlorophenyl)‐2‐phthalimidoethanesulfonamide, (II), has triclinic (P) symmetry and N‐(3‐chlorophenyl)‐2‐phthalimidoethanesulfonamide, (III), has monoclinic (P2₁/c) symmetry. The molecules of (I)–(III) are regioisomers which have crystallized in different space groups as a result of the differing intra‐ and intermolecular hydrogen‐bond interactions which are present in each structure. Compounds (I) and (II) are stabilized by N—H...O and C—H...O hydrogen bonds, while (III) is stabilized by N—H...O, C—H...O and C—H...Cl hydrogen‐bond interactions. The structure of (II) also displays π–π stacking interactions between the isoindole and benzene rings. All three structures are of interest with respect to their biological activities and have been studied as part of a programme to develop anticonvulsant drugs for the treatment of epilepsy.     

Three‐dimensional networks in bis(imidazolium) 2,2′‐dithiodibenzoate and 4‐methylimidazolium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate

Cocrystallization of imidazole or 4‐methylimidazole with 2,2′‐dithiodibenzoic acid from methanol solution yields the title 2:1 and 1:1 organic salts, 2C₃H₅N₂⁺·C₁₄H₁₀O₄S₂²⁻, (I), and C₄H₇N₂⁺·C₁₄H₁₀O₄S₂⁻, (II), respectively. Compound (I) crystallizes in the monoclinic C2/c space group with the mid‐point of the S—S bond lying on a twofold axis. The component ions in (I) are linked by intermolecular N—H...O hydrogen bonds to form a two‐dimensional network, which is further linked by C—H...O hydrogen bonds into a three‐dimensional network. In contrast, by means of N—H...O, N—H...S and O—H...O hydrogen bonds, the component ions in (II) are linked into a tape and adjacent tapes are further linked by π–π, C—H...O and C—H...π interactions, resulting in a three‐dimensional network.     

Dimers linked by type‐I C—F...F—C contacts in (Z)‐3‐methyl‐4‐[2‐(4‐methylphenyl)hydrazinylidene]‐1‐(pentafluorophenyl)‐1H‐pyrazol‐5(4H)‐one

The title compound, C₁₇H₁₁F₅N₄O, is described and compared with two closely related analogues in the literature. There are two independent molecules in the asymmetric unit, linked by N—H...O hydrogen bonds and π–π interactions into dimeric entities, presenting a noticeable noncrystallographic C₂ symmetry. These dimers are in turn linked by a medium‐strength type‐I C—F...F—C interaction into elongated tetramers. Much weaker C—H...F contacts link the tetramers into broad two‐dimensional substructures parallel to (101).     

Hydrogen‐bond‐directed supramolecular arrays in 4,4′‐bipyridinium tetrachloroterephthalate dihydrate and bis(1,10‐phenanthrolinium) tetrachloroterephthalate tetrachloroterephthalic acid trihydrate

The title compounds, C₁₀H₁₀N₂²⁺·C₈Cl₄O₄²⁻·2H₂O, (I), and 2C₁₂H₉N₂⁺·C₈Cl₄O₄²⁻·C₈H₂Cl₄O₄·3H₂O, (II), both crystallize as charge‐transfer organic salts with the dianionic or neutral acid components lying on inversion centres. The acid and base subunits in (I) arrange alternately to generate a linear tape motif via N—H...O hydrogen bonds; these tapes are further combined into a three‐dimensional architecture through multiple O—H...O and C—H...O interactions involving solvent water molecules. In contrast, the neutral and anionic acid components in (II) are linked to form a zigzag chain by means of O—H...O hydrogen bonds between acid groups, with dangling 1,10‐phenanthrolinium units connected to these chains by carboxylate–pyridinium interactions with R₂²(7) hydrogen‐bond notation. Adjacent chains are further extended to result in a two‐dimensional corrugated layer network viaπ–π interactions. Inter‐ion Cl...O interactions are also found in both (I) and (II).     

Different supramolecular architectures mediated by different weak interactions in the crystals of three N‐aryl‐2,5‐dimethoxybenzenesulfonamides

The synthesis and evaluation of the pharmacological activities of molecules containing the sulfonamide moiety have attracted interest as these compounds are important pharmacophores. The crystal structures of three closely related N‐aryl‐2,5‐dimethoxybenzenesulfonamides, namely N‐(2,3‐dichlorophenyl)‐2,5‐dimethoxybenzenesulfonamide, C₁₄H₁₃Cl₂NO₄S, (I), N‐(2,4‐dichlorophenyl)‐2,5‐dimethoxybenzenesulfonamide, C₁₄H₁₃Cl₂NO₄S, (II), and N‐(2,4‐dimethylphenyl)‐2,5‐dimethoxybenzenesulfonamide, C₁₆H₁₉NO₄S, (III), are described. The asymmetric unit of (I) consists of two symmetry‐independent molecules, while those of (II) and (III) contain one molecule each. The molecular conformations are stabilized by different intramolecular interactions, viz. C—H…O interactions in (I), N—H…Cl and C—H…O interactions in (II), and C—H…O interactions in (III). The crystals of the three compounds display different supramolecular architectures built by various weak intermolecular interactions of the types C—H…O, C—H…Cl, C—H…π(aryl), π(aryl)–π(aryl) and Cl…Cl. A detailed Hirshfeld surface analysis of these compounds has also been conducted in order to understand the relationship between the crystal structures. The d _norm and shape‐index surfaces of (I)–(III) support the presence of various intermolecular interactions in the three structures. Analysis of the fingerprint plots reveals that the greatest contribution to the Hirshfeld surfaces is from H…H contacts, followed by H…O/O…H contacts. In addition, comparisons are made with the structures of some related compounds. Putative N—H…O hydrogen bonds are observed in 29 of the 30 reported structures, wherein the N—H…O hydrogen bonds form either C (4) chain motifs or R ₂²(8) rings. Further comparison reveals that the characteristics of the N—H…O hydrogen‐bond motifs, the presence of other interactions and the resultant supramolecular architecture is largely decided by the position of the substituents on the benzenesulfonyl ring, with the nature and position of the substituents on the aniline ring exerting little effect. On the other hand, the crystal structures of (I)–(III) display several weak interactions other than the common N—H…O hydrogen bonds, resulting in supramolecular architectures varying from one‐ to three‐dimensional depending on the nature and position of the substituents on the aniline ring.     

Structural comparison of group 7 tricarbonyl complexes of 2‐{[2‐(1H‐imidazol‐4‐yl)ethyl]iminomethyl}‐5‐methylphenolate

Two tricarbonyl complexes of rhenium(I) and manganese(I) coordinated by the ligand 2‐{[2‐(1H‐imidazol‐4‐yl)ethyl]iminomethyl}‐5‐methylphenolate are reported, viz. fac‐tricarbonyl(2‐{[2‐(1H‐imidazol‐4‐yl‐κN³)ethyl]iminomethyl‐κN}‐5‐methylphenolato‐κO)rhenium(I) methanol monosolvate, [Re(C₁₆H₁₄N₃O₄)(CO)₃]·CH₃OH, (I), and fac‐tricarbonyl(2‐{[2‐(1H‐imidazol‐4‐yl‐κN³)ethyl]iminomethyl‐κN}‐5‐methylphenolato‐κO)manganese(I), fac‐[Mn(C₁₆H₁₄N₃O₄)(CO)₃], (II), display facial coordination in a distorted octahedral environment. The crystal structure of (I) is stabilized by O—H...O, N—H...O and C—H...O hydrogen‐bond interactions, while that of (II) is stabilized by N—H...O hydrogen‐bond interactions only. These interactions result in two‐dimensional networks and π–π stacking for both structures.     

Hydrogen‐bonded networks in trans‐3‐(3‐pyridyl)acrylic acid and rctt‐3,3′‐(3,4‐dicarboxycyclobutane‐1,2‐diyl)dipyridinium dichloride

The structure of trans‐3‐(3‐pyridyl)acrylic acid, C₈H₇NO₂, (I), possesses a two‐dimensional hydrogen‐bonded array of supramolecular ribbons assembled via heterodimeric synthons between the pyridine and carboxyl groups. This compound is photoreactive in the solid state as a result of close contacts between the double bonds of neighbouring molecules [3.821 (1) Å] along the a axis. The crystal structure of the photoproduct, rctt‐3,3′‐(3,4‐dicarboxycyclobutane‐1,2‐diyl)dipyridinium dichloride, C₁₆H₁₆N₂O₄²⁺·2Cl⁻, (II), consists of a three‐dimensional hydrogen‐bonded network built from crosslinking of helical chains integrated by self‐assembly of dipyridinium cations and Cl⁻ anions via different O—H...Cl, C—H...Cl and N⁺—H...Cl hydrogen‐bond interactions.     

4‐Ethynyl‐4‐hydroxycyclohexan‐1‐one and 4‐ethynyl‐4‐hydroxy‐2,3,5,6‐tetramethylcyclohexa‐2,5‐dien‐1‐one

The title compounds, C₈H₁₀O₂, (I), and C₁₂H₁₄O₂, (II), occurred as by‐products in the controlled synthesis of a series of bis­(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P2₁/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclo­hexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent mol­ecules, in the cyclo­hexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, C_methylene—H?O(H) and C_methyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis­(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here.