Divalent manganese,cobalt, copper and cadmium complexes of (Z)‐N‐benzoyl‐N′‐(1H‐1,2,4‐triazol‐3‐yl)carbamimidothioic acid: Preparation,characterization, computational and biological studies

In this work, (Z)‐N‐benzoyl‐N′‐(1H‐1,2,4‐triazol‐3‐yl)carbamimidothioic acid and its Mn(II), Co(II), Cu(II) and Cd(II) complexes were introduced for the first time. This carbonyl thiourea ligand was prepared by the reaction of 1H‐1,2,4‐triazol‐3‐amine with benzoyl isothiocyanate. The structural elucidation of these compounds was performed using elemental analysis and spectral and magnetic measurements. Octahedral structures of all complexes, except Cd(II) complex with a tetrahedral geometry, were confirmed by applying DFT structural optimization. The thermal decomposition behaviour of metal complexes of carbonyl thiourea ligand is discussed. The calculation of kinetic parameters for prepared complexes (E_a, A, ΔH*, ΔS* and ΔG*) of all thermal degradation stages has been evaluated using two comparable approaches. Antimicrobial and ABTS‐antioxidant studies indicated potent activity of Cd(II) complex compared with the other investigated compounds. The cytotoxic activity of the prepared compounds was investigated in vitro. The results indicated potent activity of Mn(II) complex against both HePG2 (liver carcinoma) and MCF‐7 (breast carcinoma) cancer cells.     

The search for formal electrostatic effects on molecular conformation and crystal packing: crystal structure of 2,2′′‐disubstituted (H versus PPh2) 1,1′‐(1,2‐phenylene)bis(3‐methyl‐1H‐imidazol‐3‐ium) bis(trifluoromethanesulfonate)

Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π‐electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C₁₄H₁₆N₄²⁺·2CF₃SO₃⁻, (2), is described and compared with that of the 2,2′′‐bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. anti for (2) and syn for (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long‐range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H…O and C—H…F contacts have no definite `hydrogen‐bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.     

Influence of the position of the methyl substituent and N‐oxide formation on the geometry and intermolecular interactions of 1‐(phenoxyethyl)piperidin‐4‐ol derivatives

Aminoalkanol derivatives have attracted much interest in the field of medicinal chemistry as part of the search for new anticonvulsant drugs. In order to study the influence of the methyl substituent and N‐oxide formation on the geometry of molecules and intermolecular interactions in their crystals, three new examples have been prepared and their crystal structures determined by X‐ray diffraction. 1‐[(2,6‐Dimethylphenoxy)ethyl]piperidin‐4‐ol, C₁₅H₂₃NO₂, 1 , and 1‐[(2,3‐dimethylphenoxy)ethyl]piperidin‐4‐ol, C₁₅H₂₃NO₂, 2 , crystallize in the orthorhombic system (space groups P2₁2₁2₁ and Pbca, respectively), with one molecule in the asymmetric unit, whereas the N‐oxide 1‐[(2,3‐dimethylphenoxy)ethyl]piperidin‐4‐ol N‐oxide monohydrate, C₁₅H₂₃NO₃·H₂O, 3 , crystallizes in the monoclinic space group P2₁/c, with one N‐oxide molecule and one water molecule in the asymmetric unit. The geometries of the investigated compounds differ significantly with respect to the conformation of the O—C—C linker, the location of the hydroxy group in the piperidine ring and the nature of the intermolecular interactions, which were investigated by Hirshfeld surface and corresponding fingerprint analyses. The crystal packing of 1 and 2 is dominated by a network of O—H…N hydrogen bonds, while in 3 , it is dominated by O—H…O hydrogen bonds and results in the formation of chains.     

Weak hydrogen and halogen bonding in 4‐[(2,2‐difluoroethoxy)methyl]pyridinium iodide and 4‐[(3‐chloro‐2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium iodide

To enable a comparison between a C—H…X hydrogen bond and a halogen bond, the structures of two fluorous‐substituted pyridinium iodide salts have been determined. 4‐[(2,2‐Difluoroethoxy)methyl]pyridinium iodide, C₈H₁₀F₂NO⁺·I⁻, (1), has a –CH₂OCH₂CF₂H substituent at the para position of the pyridinium ring and 4‐[(3‐chloro‐2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium iodide, C₉H₉ClF₄NO⁺·I⁻, (2), has a –CH₂OCH₂CF₂CF₂Cl substituent at the para position of the pyridinium ring. In salt (1), the iodide anion is involved in one N—H…I and three C—H…I hydrogen bonds, which, together with C—H…F hydrogen bonds, link the cations and anions into a three‐dimensional network. For salt (2), the iodide anion is involved in one N—H…I hydrogen bond, two C—H…I hydrogen bonds and one C—Cl…I halogen bond; additional C—H…F and C—F…F interactions link the cations and anions into a three‐dimensional arrangement.     

Solvent influence on the crystal packing of 6‐aminothiocytosine

The crystal structures of 6‐aminothiocytosine (systematic name: 4,6‐diamino‐1,2‐dihydropyrimidine‐2‐thione, DAPMT, C₄H₆N₄S), its hemihydrate (0.5H₂O) and its dimethylformamide (DMF, C₃H₇NO) monosolvate were compared, and the influence of the type of solvent on the supramolecular motifs was analysed. In all three crystal structures, there are two symmetry‐independent molecules (A and B), and these molecules are connected by three relatively short and directional hydrogen bonds to form chains of alternating A and B molecules. A further organization of these chains is dependent on the nature of the solvent molecule. In the unsolvated form, two orientations of the neighbouring chains are observed, and similar motifs – but only one per structure – can be observed in the solvated structures. These two different motifs can be connected by two different kinds of contacts, i.e. either π–π (hemihydrate) or staple‐supported S…S (DMF). In the crystal structures, the O atoms of the solvent molecules are double acceptors of the same type of hydrogen bonds and bind the chains of DAPMT molecules into different motifs (dimeric or infinite chains). A Hirshfeld fingerprint analysis was used for visualization and additional interpretation of these results.     

Crystallographic study of self‐organization in the solid state including quasi‐aromatic pseudo‐ring stacking interactions in 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea

1‐Benzoylthioureas contain both carbonyl and thiocarbonyl functional groups and are of interest for their biological activity, metal coordination ability and involvement in hydrogen‐bond formation. Two novel 1‐benzoylthiourea derivatives, namely 1‐benzoyl‐3‐(3,4‐dimethoxyphenyl)thiourea, C₁₆H₁₆N₂O₃S, (I), and 1‐benzoyl‐3‐(2‐hydroxypropyl)thiourea, C₁₁H₁₄N₂O₂S, (II), have been synthesized and characterized. Compound (I) crystallizes in the space group P , while (II) crystallizes in the space group P 2₁/c . In both structures, intramolecular N—H…O hydrogen bonding is present. The resulting six‐membered pseudo‐rings are quasi‐aromatic and, in each case, interact with phenyl rings via stacking‐type interactions. C—H…O, C—H…S and C—H…π interactions are also present. In (I), there is one molecule in the asymmetric unit. Pairs of molecules are connected via two intermolecular N—H…S hydrogen bonds, forming centrosymmetric dimers. In (II), there are two symmetry‐independent molecules that differ mainly in the relative orientations of the phenyl rings with respect to the thiourea cores. Additional strong hydrogen‐bond donor and acceptor –OH groups participate in the formation of intermolecular N—H…O and O—H…S hydrogen bonds that join molecules into chains extending in the [001] direction.     

The role of different nonspecific interactions and halogen contacts in the crystal structure organization of 5‐chloroisatoic anhydride

The crystal structure of 6‐chloro‐2,4‐dihydro‐1H‐3,1‐benzoxazine‐2,4‐dione (5‐chloroisatoic anhydride), C₈H₄ClNO₃, has been determined and analysed in terms of connectivity and packing patterns. The compound crystallizes in the noncentrosymmetric space group Pna2₁ with one molecule in the asymmetric unit. The role of different weak interactions is discussed with respect to three‐dimensional network organization. Molecules are extended into one‐dimensional helical arrangements, making use of N—H…O hydrogen bonds and π–π interactions. The helices are further organized into monolayers via weak C—H…O and lone pair–π interactions, and the monolayers are packed into a noncentrosymmetric three‐dimensional architecture by C—Cl…π interactions and C—H…Cl and Cl…Cl contacts. A Hirshfeld surface (HS) analysis was carried out and two‐dimensional (2D) fingerprint plots were generated to visualize the intermolecular interactions and to provide quantitative data for their relative contributions. In addition, tests of the antimicrobial activity and in vitro cytotoxity effects against fitoblast L929 were performed and are discussed.     

Structures of N—（2,3,4,6—Tetra—O—acetyl—β—D—glycosyl） thiocarbamic Benzoyl Hydrazine

The crystal structure of N-(2,3,4,6-tetra-O-acetyl-β-D-gly-cosyl)-thiocarbamic benzoyl hydrazine(C22H27N3O9S) was determined by X-ray diffracton method.The hexopyranosyl ring adopts a chair conformation.All the ring substituents are in the equatorial positions.The acetoxyl-methyl group is in synclinal conformation.The S atom is in synperiplanar conformation while the benzoyl hydrazine moiety is anti-periplanar.The thiocarbamic moiety is almost companar with the benzoyl hydrazine group.There are two intramolecular hydrogen bonds and one intermolecular hydrogen bond for each molecule in the crystal structure.The molecules form a network structure through intermolecular hydrogen bonds.     

The interplay of solvation,molecular conformation and supramolecular assembly in 1,1′‐({[(ethane‐1,2‐diyl)dioxy](1,2‐phenylene)}bis(methanylylidene))bis(thiosemicarbazide) and its N,N‐dimethylformamide disolvate

The wide diversity of applications of thiosemicarbazones and bis(thiosemicarbazones) has seen them used as anticancer and antitubercular agents, and as ligands in metal complexes designed to act as site‐specific radiopharmaceuticals. Molecules of 1,1′‐({[(ethane‐1,2‐diyl)dioxy](1,2‐phenylene)}bis(methanylylidene))bis(thiosemicarbazide) {alternative name: 2,2′‐[ethane‐1,2‐diylbis(oxy)]dibenzaldehyde bis(thiosemicarbazide)}, C₁₈H₂₀N₆O₂S₂, (I), lie across twofold rotation axes in the space group C2/c, with an O—C—C—O torsion angle of −59.62 (13)° and a trans‐planar arrangement of the thiosemicarbazide fragments relative to the adjacent aryl rings. The molecules of (I) are linked by N—H...S hydrogen bonds to form sheets containing R²₄(38) rings and two types of R²₂(8) ring. In the N,N‐dimethylformamide disolvate, C₁₈H₂₀N₆O₂S₂·2C₃H₇NO, (II), the independent molecular components all lie in general positions, but one of the solvent molecules is disordered over two sets of atomic sites having occupancies of 0.839 (3) and 0.161 (3). The O—C—C—O torsion angle in the ArOCH₂CH₂OAr component is −75.91 (14)° and the independent thiosemicarbazide fragments both adopt a cis‐planar arrangement relative to the adjacent aryl rings. The ArOCH₂CH₂OAr components in (II) are linked by N—H...S hydrogen bonds to form deeply puckered sheets containing R²₂(8), R²₄(8) and two types of R²₂(38) rings, and which contain cavities which accommodate all of the solvent molecules in the interior of the sheets. Comparisons are made with some related compounds.     

Effect of the position of a methoxy substituent on the antimicrobial activity and crystal structures of 4‐methyl‐1,6‐diphenylpyrimidine‐2(1H)‐selenone derivatives

Derivatives of pyrimidine‐2(1H)‐selenone are a group of compounds with very strong antimicrobial activity. In order to study the effect of the position of the methoxy substituent on biological activity, molecular geometry and intermolecular interactions in the crystal, three derivatives were prepared and evaluated with respect to their antimicrobial activities, and their crystal structures were determined by X‐ray diffraction. The investigated compounds, namely, 1‐(X‐methoxyphenyl)‐4‐methyl‐6‐phenylpyrimidine‐2(1H)‐selenones (X = 2, 3 and 4 for 1 , 2 and 3 , respectively), C₁₈H₁₆N₂OSe, showed very strong activity against selected strains of Gram‐positive bacteria and fungi. Two compounds, 1 and 2 , crystallize in the monoclinic space group P2₁/c, while 3 crystallizes in the space group P2₁/n; 1 has two molecules in the asymmetric unit and the other two ( 2 and 3 ) have one molecule. The geometries of the investigated compounds differ slightly in the mutual orientations of the aromatic and pyrimidineselenone rings. The O atom in 1 stabilizes the conformation of the molecules via intramolecular C—H…O hydrogen bonding. The packing of molecules is determined by weak C—H…N and C—H…Se intermolecular interactions and additionally in 1 and 2 by C—H…O intermolecular interactions. The introduction of the methoxy substituent results in greater selectivity of the investigated compounds.     

Nontypical iodine–halogen bonds in the crystal structure of (3E)‐8‐chloro‐3‐iodomethylidene‐2,3‐dihydro‐1,4‐oxazino[2,3,4‐ij]quinolin‐4‐ium triiodide

Two kinds of iodine–iodine halogen bonds are the focus of our attention in the crystal structure of the title salt, C₁₂H₈ClINO⁺·I₃⁻, described by X‐ray diffraction. The first kind is a halogen bond, reinforced by charges, between the I atom of the heterocyclic cation and the triiodide anion. The second kind is the rare case of a halogen bond between the terminal atoms of neighbouring triiodide anions. The influence of relatively weakly bound iodine inside an asymmetric triiodide anion on the thermal and Raman spectroscopic properties has been demonstrated.     

Weak hydrogen bonding and fluorous interactions in the chloride and bromide salts of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium

Neutralization of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridine with hydrohalo acids HX (X = Cl and Br) yielded the pyridinium salts 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium chloride, C₉H₁₀F₄NO⁺·Cl⁻, (1), and 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium bromide, C₉H₁₀F₄NO⁺·Br⁻, (2), both carrying a fluorous side chain at the para position of the pyridinium ring. Single‐crystal X‐ray diffraction techniques revealed that (1) and (2) are isomorphous. The halide anions accept four hydrogen bonds from N—H, ortho‐C—H and CF₂—H groups. Two cations and two anions form a centrosymmetric dimeric building block, utilizing complimentary N—H…X …H—Csp ³ connections. These dimers are further crosslinked, utilizing another complimentary Csp ²—H…X …H—Csp ² connection. The pyridinium rings are π‐stacked, forming columns running parallel to the a axis that make angles of ca 44–45° with the normal to the pyridinium plane. There are also supramolecular C—H…F—C interactions, namely bifurcated C—H…F and bifurcated C—F…H interactions; additionally, one type II C—F…F—C halogen bond has been observed.     

Synthesis,crystal structure and magnetic properties of diaquabis(2,6‐diamino‐7H‐purin‐1‐ium‐κN9)bis(4,4′‐oxydibenzoato‐κO)cobalt(II) dihydrate

The title mononuclear Co^II complex, [Co(C₅H₇N₆)₂(C₁₄H₈O₅)₂(H₂O)₂]·2H₂O, has been synthesized and its crystal structure determined by X‐ray diffraction. The complex crystallizes in the triclinic space group P, with one formula unit per cell (Z = 1 and Z′ = ). It consists of a mononuclear unit with the Co^II ion on an inversion centre coordinated by two 2,6‐diamino‐7H‐purin‐1‐ium cations, two 4,4′‐oxydibenzoate anions (in a nonbridging κO‐monodentate coordination mode, which is less common for the anion in its Co^II complexes) and two water molecules, defining an octahedral environment around the metal atom. There is a rich assortment of nonbonding interactions, among which a strong N⁺—H…O⁻ bridge, with a short N…O distance of 2.5272 (18) Å, stands out, with the H atom ostensibly displaced away from its expected position at the donor side, towards the acceptor. The complex molecules assemble into a three‐dimensional hydrogen‐bonded network. A variable‐temperature magnetic study between 2 and 300 K reveals an orbital contribution to the magnetic moment and a weak antiferromagnetic interaction between Co^II centres as the temperature decreases. The model leads to the following values: A (crystal field strength) = 1.81, λ (spin‐orbit coupling) = −59.9 cm⁻¹, g (Landé factor) = 2.58 and zJ (exchange coupling) = −0.5 cm⁻¹.     

Two polymorphs of N‐(2‐methoxyphenyl)‐4‐oxo‐4H‐chromone‐3‐carboxamide

The title compound, C₁₇H₁₃NO₄, crystallizes in two polymorphic forms, each with two molecules in the asymmetric unit and in the monoclinic space group P2₁/c. All of the molecules have intramolecular hydrogen bonds involving the amide group. The amide N atoms act as donors to the carbonyl group of the pyrone and also to the methoxy group of the benzene ring. The carbonyl O atom of the amide group acts as an acceptor of the β and β′ C atoms belonging to the aromatic rings. These intramolecular hydrogen bonds have a profound effect on the molecular conformation. In one polymorph, the molecules in the asymmetric unit are linked to form dimers by weak C—H...O interactions. In the other, the molecules in the asymmetric unit are linked by a single weak C—H...O hydrogen bond. Two of these units are linked to form centrosymmetric tetramers by a second weak C—H...O interaction. Further interactions of this type link the molecules into chains, so forming a three‐dimensional network. These interactions in both polymorphs are supplemented by π–π interactions between the chromone rings and between the chromone and methoxyphenyl rings.     

An unusual conformation of gabapentin (Gpn) in Pyr‐Gpn‐NH‐NH‐Pyr stabilized by weak interactions

The crystal structure of N‐[(1‐{2‐oxo‐2‐[2‐(pyrazin‐2‐ylcarbonyl)hydrazin‐1‐yl]ethyl}cyclohexyl)methyl]pyrazine‐2‐carboxamide monohydrate (Pyr‐Gpn‐NN‐NH‐Pyr·H₂O), C₁₉H₂₃N₇O₃·H₂O, reveals an unusual trans–gauche (tg⁻) conformation for the gabapentin (Gpn) residue around the C^γ—C^β (θ₁) and C^β—C^α (θ₂) bonds. The molecular conformation is stabilized by intramolecular N—H...N hydrogen bonds and weak C—H...O interactions. The packing of the molecules in the crystal lattice shows a network of strong N—H...O and O—H...O hydrogen bonds together with weak C—H...O and π–π inteactions.     

Solid‐state conformations of linear depsipeptide amides with an alternating sequence of α,α‐disubstituted α‐amino acid and α‐hydroxy acid

Depsipeptides and cyclodepsipeptides are analogues of the corresponding peptides in which one or more amide groups are replaced by ester functions. Reports of crystal structures of linear depsipeptides are rare. The crystal structures and conformational analyses of four depsipeptides with an alternating sequence of an α,α‐disubstituted α‐amino acid and an α‐hydroxy acid are reported. The molecules in the linear hexadepsipeptide amide in (S)‐Pms‐Acp‐(S)‐Pms‐Acp‐(S)‐Pms‐Acp‐NMe₂ acetonitrile solvate, C₄₇H₅₈N₄O₉·C₂H₃N, ( 3b ), as well as in the related linear tetradepsipeptide amide (S)‐Pms‐Aib‐(S)‐Pms‐Aib‐NMe₂, C₂₈H₃₇N₃O₆, ( 5a ), the diastereoisomeric mixture (S,R)‐Pms‐Acp‐(R,S)‐Pms‐Acp‐NMe₂/(R,S)‐Pms‐Acp‐(R,S)‐Pms‐Acp‐NMe₂ (1:1), C₃₂H₄₁N₃O₆, ( 5b ), and (R,S)‐Mns‐Acp‐(S,R)‐Mns‐Acp‐NMe₂, C₃₀H₃₇N₃O₆, ( 5c ) (Pms is phenyllactic acid, Acp is 1‐aminocyclopentanecarboxylic acid and Mns is mandelic acid), generally adopt a β‐turn conformation in the solid state, which is stabilized by intramolecular N—H…O hydrogen bonds. Whereas β‐turns of type I (or I′) are formed in the cases of ( 3b ), ( 5a ) and ( 5b ), which contain phenyllactic acid, the torsion angles for ( 5c ), which incorporates mandelic acid, indicate a β‐turn in between type I and type III. Intermolecular N—H…O and O—H…O hydrogen bonds link the molecules of ( 3a ) and ( 5b ) into extended chains, and those of ( 5a ) and ( 5c ) into two‐dimensional networks.     

Crystal structures of four δ‐keto esters and a Cambridge Structural Database analysis of cyano–halogen interactions

The revived interest in halogen bonding as a tool in pharmaceutical cocrystals and drug design has indicated that cyano–halogen interactions could play an important role. The crystal structures of four closely related δ‐keto esters, which differ only in the substitution at a single C atom (by H, OMe, Cl and Br), are compared, namely ethyl 2‐cyano‐5‐oxo‐5‐phenyl‐3‐(piperidin‐1‐yl)pent‐2‐enoate, C₁₉H₂₂N₂O₃, (1), ethyl 2‐cyano‐5‐(4‐methoxyphenyl)‐5‐oxo‐3‐(piperidin‐1‐yl)pent‐2‐enoate, C₂₀H₂₄N₂O₄, (2), ethyl 5‐(4‐chlorophenyl)‐2‐cyano‐5‐oxo‐3‐(piperidin‐1‐yl)pent‐2‐enoate, C₁₉H₂₁ClN₂O₃, (3), and the previously published ethyl 5‐(4‐bromophenyl)‐2‐cyano‐5‐oxo‐3‐(piperidin‐1‐yl)pent‐2‐enoate, C₁₉H₂₁BrN₂O₃, (4) [Maurya, Vasudev & Gupta (2013). RSC Adv. 3 , 12955–12962]. The molecular conformations are very similar, while there are differences in the molecular assemblies. Intermolecular C—H...O hydrogen bonds are found to be the primary interactions in the crystal packing and are present in all four structures. The halogenated derivatives have additional aromatic–aromatic interactions and cyano–halogen interactions, further stabilizing the molecular packing. A database analysis of cyano–halogen interactions using the Cambridge Structural Database [CSD; Groom & Allen (2014). Angew. Chem. Int. Ed. 53 , 662–671] revealed that about 13% of the organic molecular crystals containing both cyano and halogen groups have cyano–halogen interactions in their packing. Three geometric parameters for the C—X...N[triple‐bond]C interaction (X = F, Cl, Br or I), viz. the N...X distance and the C—X...N and C—N...X angles, were analysed. The results indicate that all the short cyano–halogen contacts in the CSD can be classified as halogen bonds, which are directional noncovalent interactions.     

Influence of fluorine substitution on the molecular conformation of 3′‐deoxy‐3′‐fluoro‐5‐methyluridine

Fluorine substitutions on the furanose ring of nucleosides are known to strongly influence the conformational properties of oligonucleotides. In order to assess the effect of fluorine on the conformation of 3′‐deoxy‐3′‐fluoro‐5‐methyluridine (^RT^F), C₁₀H₁₃FN₂O₅, we studied its stereochemistry in the crystalline state using X‐ray crystallography. The compound crystallizes in the chiral orthorhombic space group P2₁2₁2₁ and contains two symmetry‐independent molecules (A and B) in the asymmetric unit. The furanose ring in molecules A and B adopts conformations between envelope (²E, 2′‐endo, P = 162°) and twisted (²T₃, 2′‐endo and 3′exo, P = 180°), with pseudorotation phase angles (P) of 164.3 and 170.2°, respectively. The maximum puckering amplitudes, ν_max, for molecules A and B are 38.8 and 36.1°, respectively. In contrast, for 5‐methyluridine (^RT^OH), the value of P is 21.2°, which is between the ³E (3′‐endo, P = 18.0°) and ³T₄ (3′‐endo and 4′‐exo, P = 36°) conformations. The value of ν_max for ^RT^OH is 41.29°. Molecules A and B of ^RT^F generate respective helical assemblies across the crystallographic 2₁‐screw axis through classical N—H…O aand O—H…O hydrogen bonds supplemented by C—H…O contacts. Adjacent parallel helices of both molecules are linked to each other via O—H…O and O…π interactions.     

Synthesis,crystal structure and study of the crystal packing in the complex bis(4‐aminopyridine‐κN1)dichloridocobalt(II)

Despite the large number of reported crystalline structures of coordination complexes bearing pyridines as ligands, the relevance of π–π interactions among these hereroaromatic systems in the stabilization of their supramolecular structures and properties is not very well documented in the recent literature. The title compound, [CoCl₂(C₅H₆N₂)₂], was obtained as bright‐blue crystals suitable for single‐crystal X‐ray diffraction analysis from the reaction of 4‐aminopyridine with cobalt(II) chloride in ethanol. The new complex was fully characterized by a variety of spectroscopic techniques and single‐crystal X‐ray diffraction. The crystal structure showed a tetrahedral complex stabilized mainly by bidimensional motifs constructed by π–π interactions with large horizontal displacements between the 4‐aminopyridine units, and N—H…Cl hydrogen bonds. Other short contacts, such as C—H…Cl interactions, complete the three‐dimensional arrangement. The supramolecular investigation was extended by statistical studies using the Cambridge Structural Database and a Hirshfeld surface analysis.