In the title benzyl­ideneaniline Schiff base, C18H22N2O, the aromatic rings are inclined to each other by 46.01 (6)°, while the Car—N= C—Car torsion angle is 176.9 (1)°. In the crystal, the only identifiable directional inter­action is a weak C—H⋯π hydrogen bond, which generates inversion dimers that stack along the a-axis direction.

The (S)-(+)-1-(4-bromo­phen­yl)-N-[(4-methoxyphen­yl)methyl­idene]ethyl­amine ligand, C16H16BrNO, (I), was synthesized through the reaction of 4-meth­oxy­anisaldehyde with (S)-(−)-1-(4-bromo­phen­yl)ethyl­amine. It crystallizes in the ortho­rhom­bic space group P212121 belonging to the Sohncke group, featuring a single mol­ecule in the asymmetric unit. The refinement converged successfully, achieving an R factor of 0.0508. The PdII com­plex bis­{(S)-(+)-1-(4-bromo­phen­yl)-N-[(4-methoxyphen­yl)methyl­idene]ethyl­amine-κN}di­chlorido­pal­ladium(II), [PdCl2(C16H16BrNO)2], (II), crystallizes in the monoclinic space group P21 belonging to the Sohncke group, with two mol­ecules in the asymmetric unit. The central atom is tetra­coordinated by two N atoms and two Cl atoms, resulting in a square-planar configuration. The imine moieties exhibit a trans configuration around the PdII centre, with average Cl—Pd—N angles of approximately 89.95 and 90°. The average distances within the palladium com­plex for the two mol­ecules are ∼2.031 Å for Pd—N and ∼2.309 Å for Pd—Cl.

The crystal structures and Hirshfeld surface analyses of three similar azo compounds are reported. Methyl 4-{2,2-di­chloro-1-[(E)-phenyl­diazen­yl]ethen­yl}benzoate, C16H12Cl2N2O2, (I), and methyl 4-{2,2-di­chloro-1-[(E)-(4-methyl­phen­yl)diazen­yl]ethen­yl}benzoate, C17H14Cl2N2O2, (II), crystallize in the space group P21/c with Z = 4, and methyl 4-{2,2-di­chloro-1-[(E)-(3,4-di­methyl­phen­yl)diazen­yl]ethen­yl}benzoate, C18H16Cl2N2O2, (III), in the space group Poverline{1} with Z = 2. In the crystal of (I), mol­ecules are linked by C—H⋯N hydrogen bonds, forming chains with C(6) motifs parallel to the b axis. Short inter­molecular Cl⋯O contacts of 2.8421 (16) Å and weak van der Waals inter­actions between these chains stabilize the crystal structure. In (II), mol­ecules are linked by C—H⋯O hydrogen bonds and C—Cl⋯π inter­actions, forming layers parallel to (010). Weak van der Waals inter­actions between these layers consolidate the mol­ecular packing. In (III), mol­ecules are linked by C—H⋯π and C—Cl⋯π inter­actions forming chains parallel to [011]. Furthermore, these chains are connected by C—Cl⋯π inter­actions parallel to the a axis, forming (0overline{1}1) layers. The stability of the mol­ecular packing is ensured by van der Waals forces between these layers.

The title compound, C16H17N3O3, is racemic as it crystallizes in a centrosymmetric space group (Poverline{1}), although the trans disposition of substituents about the central C—C bond is established. The five- and six-membered rings are oriented at a dihedral angle of 75.88 (8)°. In the crystal, N—H⋯N hydrogen bonds form chains of mol­ecules extending along the c-axis direction that are connected by inversion-related pairs of O—H⋯N into ribbons. The ribbons are linked by C—H⋯π(ring) inter­actions, forming layers parallel to the ab plane. A Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (45.9%), H⋯N/N⋯H (23.3%), H⋯C/C⋯H (16.2%) and H⋯O/O⋯H (12.3%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. The volume of the crystal voids and the percentage of free space were calculated to be 100.94 Å3 and 13.20%, showing that there is no large cavity in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicates that the stabilization is dominated by the electrostatic energy contributions in the title compound. Moreover, the DFT-optimized structure at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

Single crystals of two basic cadmium phosphates, dicadmium orthophosphate hydroxide, Cd2(PO4)OH, and penta­cadmium bis­(orthophosphate) tetra­kis­(hydroxide), Cd5(PO4)2(OH)4, were obtained under hydro­thermal conditions. Cd2(PO4)OH adopts the triplite [(Mn,Fe)2(PO4)F] structure type. Its asymmetric unit comprises two Cd, one P and five O sites, all situated at the general Wyckoff position 8 f of space group I2/a; two of the O atoms are positionally disordered over two sites, and the H atom could not be localized. Disregarding the disorder, distorted [CdO6] polyhedra form a tri-periodic network by edge-sharing with neighbouring [CdO6] units and by vertex-sharing with [PO4] units. The site associated with the OH group is coordinated by four Cd atoms in a distorted tetra­hedral manner forming 1∞[(OH)Cd4/2] chains parallel to [001]. The oxygen environment around the OH site suggests multiple acceptor atoms for possible O—H⋯O hydrogen-bonding inter­actions and is the putative reason for the disorder. Cd5(PO4)2(OH)4 adopts the arsenoclasite [Mn5(AsO4)2(OH)4] structure type. Its asymmetric unit comprises five Cd, two P, and twelve O sites all located at the general Wyckoff position 4 a of space group P212121; the H atoms could not be localized. The crystal structure of Cd5(PO4)2(OH)4 can be subdivided into two main sub-units. One consists of three edge-sharing [CdO6] octa­hedra, and the other of two edge- and vertex-sharing [CdO6] octa­hedra. Each sub-unit forms corrugated ribbons extending parallel to [100]. The two types of ribbons are linked into the tri-periodic arrangement through vertex-sharing and through common [PO4] tetra­hedra. Qu­anti­tative structure comparisons are made with isotypic M5(XO4)2(OH)4 crystal structures (M = Cd, Mn, Co; X = P, As, V).

The title compound, C27H20N4O3S, crystallizes in the monoclinic system, space group P21/n, with Z = 4. The global shape of the mol­ecule is determined by the orientation of the substituents on the central 4H-1,2,4-triazole ring. The nitro­phenyl ring, phenyl ring, and naphthalene ring system are oriented at dihedral angles of 82.95 (17), 77.14 (18) and 89.46 (15)°, respectively, with respect to the triazole ring. The crystal packing features chain formation in the b-axis direction by S⋯O inter­actions. A Hirshfeld surface analysis indicates that the highest contributions to surface contacts arise from contacts in which H atoms are involved.

A new lanthanide coordination polymer, poly[[tri­aqua­bis­(μ4-phthalato)(μ3-pyridine-2,5-di­carboxyl­ato)dipraseodymium] monohydrate], {[Pr2(C7H3NO4)2(C8H4O4)(H2O)3]·H2O}n or {[Pr2(phth)2(pydc)(H2O)3]·H2O}n, (pydc2− = pyridine-2,5-di­carboxyl­ate and phth2− = phthalate) was synthesized and characterized, revealing the structure to be an assembly of di-periodic {Pr2(pydc)(phth)2(H2O)3}n layers. Each layer is built up by edge-sharing {Pr2N2O14} and {Pr2O16} dimers, which are connected through a new coordin­ation mode of pydc2− and phth2−. These layers are stabilized by inter­nal hydrogen bonds and π–π inter­actions. In addition, a three-dimensional supra­molecular framework is built by inter­layer hydrogen-bonding inter­actions involving the non-coordinated water mol­ecule. Thermogravimetric analysis shows that the title compound is thermally stable up to 400°C.

The title compound [systematic name: 1-(2-nitro­phen­yl)pyrrole-2,5-dione], C10H6N2O4, crystallizes in the monoclinic system (space group P21/n) with two mol­ecules in the asymmetric unit, which are linked by C—H⋯O hydrogen bonds. Hirshfeld surface analysis showed that the most significant contributions to the crystal packing are from H⋯O/O⋯H, H⋯C/C⋯H and H⋯H inter­actions, which contribute 54.7%, 15.2% and 15.6%, respectively. A DFT study was conducted using three different levels of theory [(B3LYP/6–311+G(d,p), wB97XD/Def2TZVPP and LC-wpbe/6–311(2 d,2p)] in order to determine the stability, structural and electronic properties of the title mol­ecule with a view to its potential applications and photochemical and copolymer properties.

The title compound, [CdBr2(C6H14N2O)], was synthesized upon complexation of 4-(2-aminoethyl)morpholine and cadmium(II) bromide tetra­hydrate at 303 K. It crystallizes as a centrosymmetric dimer, with one cadmium atom, two bromine atoms and one N,N'-bidentate 4-(2-aminoethyl)morpholine ligand in the asymmetric unit. The metal atom is six-coordinated and has a distorted octa­hedral geometry. In the crystal, O⋯Cd inter­actions link the dimers into a polymeric double chain and inter­molecular C—H⋯O hydrogen bonds form R22(6) ring motifs. Further C—H⋯Br and N—H⋯Br hydrogen bonds link the components into a three-dimensional network. As the N—H⋯Br hydrogen bonds are shorter than the C—H⋯Br inter­actions, they have a larger effect on the packing. A Hirshfeld surface analysis reveals that the largest contributions to the packing are from H⋯H (46.1%) and Br⋯H/H⋯Br (38.9%) inter­actions with smaller contributions from the O⋯H/H⋯O (4.7%), Br⋯Cd/Cd⋯Br (4.4%), O⋯Cd/Cd⋯O (3.5%), Br⋯Br (1.1%), Cd⋯H/H⋯Cd (0.9%), Br⋯O/O⋯Br (0.3%) and O⋯N/N⋯O (0.1%) contacts.

The title mol­ecule, [Fe2(C5H5)2(C23H17ClN2)]·C3H7NO, is twisted end to end and the central N/C/N unit is disordered. In the crystal, several C—H⋯π(ring) inter­actions lead to the formation of layers, which are connected by further C—H⋯π(ring) inter­actions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (60.2%) and H⋯C/C⋯H (27.0%) inter­actions. Hydrogen bonding, C—H⋯π(ring) inter­actions and van der Waals inter­actions dominate the crystal packing.

The crystal structures and Hirshfeld surface analyses of three similar compounds are reported. Methyl 4-[4-(di­fluoro­meth­oxy)phen­yl]-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carboxyl­ate, (C21H23F2NO4), (I), crystallizes in the monoclinic space group C2/c with Z = 8, while isopropyl 4-[4-(di­fluoro­meth­oxy)phen­yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carb­oxyl­ate, (C23H27F2NO4), (II) and tert-butyl 4-[4-(di­fluoro­meth­oxy)phen­yl]-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexa­hydro­quinoline-3-carboxyl­ate, (C24H29F2NO4), (III) crystallize in the ortho­rhom­bic space group Pbca with Z = 8. In the crystal structure of (I), mol­ecules are linked by N—H⋯O and C—H⋯O inter­actions, forming a tri-periodic network, while mol­ecules of (II) and (III) are linked by N—H⋯O, C—H⋯F and C—H⋯π inter­actions, forming layers parallel to (002). The cohesion of the mol­ecular packing is ensured by van der Waals forces between these layers. In (I), the atoms of the 4-di­fluoro­meth­oxy­phenyl group are disordered over two sets of sites in a 0.647 (3): 0.353 (3) ratio. In (III), the atoms of the dimethyl group attached to the cyclo­hexane ring, and the two carbon atoms of the cyclo­hexane ring are disordered over two sets of sites in a 0.646 (3):0.354 (3) ratio.

The crystal structure of the tetra­ethyl­ammonium salt of the non-steroidal anti-inflammatory drug nimesulide (polymorph II) (systematic name: tetra­ethyl­ammonium N-methane­sulfonyl-4-nitro-2-phen­oxy­anilinide), C8H20N+·C13H11N2O5S−, was determined using single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic space group P21/c with one tetra­ethyl­ammonium cation and one nimesulide anion in the asymmetric unit. In the crystal, the ions are linked by C—H⋯N and C—H⋯O hydrogen bonds and C—H⋯π inter­actions. There are differences in the geometry of both the nimesulide anion and the tetra­ethyl­ammonium cation in polymorphs I [Rybczyńska & Sikorski (2023). Sci. Rep. 13, 17268] and II of the title compound.

An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen, C14H8N4O2. In the crystal structure, weak C—H⋯O hydrogen bonds and π–π stacking inter­actions link the mol­ecules. The structure exhibits disorder of the mol­ecule.

In the title compound, C31H24N4O2, the quinoxaline units are distinctly non-planar and twisted end-to-end. In the crystal, C—H⋯O and C—H⋯N hydrogen bonds link the mol­ecules into chains extending along the a-axis direction. The chains are linked through π-stacking inter­actions between inversion-related quinoxaline moieties.

The neutral organosilicon(IV) complex, (C6F5)2Si(OPO)2 (OPO = 1-oxopyridin-2-one, C5H4NO2), was synthesized from (C6F5)2Si(OCH3)2 and 2 equiv. of 1-hy­droxy­pyridin-2-one in tetra­hydro­furan (THF). Single crystals grown from the diffusion of n-pentane into a THF solution were identified as a THF hemisolvate and an n-pentane hemisolvate, (C6F5)2Si(OPO)2·0.5THF·0.5C5H12 (1). p-Tol­yl2Si(OPO)2 (2) and mesit­yl2Si(OPO)2 (3) crystallized directly from reaction mixtures of 2 equiv. of Me3Si(OPO) with p-tol­yl2SiCl2 and mesit­yl2SiCl2, respectively, in aceto­nitrile. The oxygen-bonded carbon and nitro­gen atoms of the OPO ligands in 1, 2, and 3 were modeled as disordered indicating co-crystallization of up to three possible diastereomers in each. Solution NMR studies support the presence of exclusively the all-cis isomer in 1 and multiple isomers in 2. Poor solubility of 3 limited its characterization in solution.

The title compound, C14H12N2O4, was obtained from 2-acetyl-6-amino­naphthalene through two-step reactions of acetyl­ation and nitration. The mol­ecule comprises the naphthalene ring system consisting of functional systems bearing a acetyl group (C-2), a nitro group (C-5), and an acetyl­amino group (C-6). In the crystal, the mol­ecules are assembled into two-dimensional sheet-like structures by inter­molecular N—H⋯O and C—H⋯O hydrogen-bonding inter­actions. Hirshfeld surface analysis illustrates that the most important contributions to the crystal packing are from O⋯H/H⋯O (43.7%), H⋯H (31.0%), and C⋯H/H⋯C (8.5%) contacts.

In the title compound, C21H15N5OS2, mol­ecular pairs are linked by N—H⋯N hydrogen bonds along the c-axis direction and C—H⋯S and C—H⋯O hydrogen bonds along the b-axis direction, with R22(12) and R22(16) motifs, respectively, thus forming layers parallel to the (10overline{4}) plane. In addition, C=S⋯π and C≡N⋯π inter­actions between the layers ensure crystal cohesion. The Hirshfeld surface analysis indicates that the major contributions to the crystal packing are H⋯H (43.0%), C⋯H/H⋯C (16.9%), N⋯H/H⋯N (11.3%) and S⋯H/H⋯S (10.9%) inter­actions.

Since its founding in 2013, the Young Crystallographers (YC) have become one of the most active working groups not only within their parent organization, the German Crystallographic Society (DGK), but also among other young crystallographers' groups in Europe and the world. The aim of the YC is and always has been to support early-career researchers in the diverse fields of crystallography and the rejuvenation of the field on a national scale. Over the past decade, we have curated events, platforms, and educational content tailored to foster collaboration and knowledge transfer among young crystallographers. In this article, we introduce our group and show how this active and diverse community has shaped the rejuvenation of crystallography in Germany, strengthened by the support of our national society.

The title compound, C25H18N4, crystallizes in the centrosymmetric ortho­rhom­bic space group Pbca, with eight mol­ecules in the unit cell. The main feature noticeable in the structure is the impact of the tri­cyano­vinyl (TCV) group in forcing partial planarity of the portion of the mol­ecule carrying the TCV group and directing the mol­ecular packing in the solid state, resulting in the formation of π-stacks of dimers within the unit cell. Short π–π stack closest atom-to-atom distances of 3.444 (15) Å are observed. Such motif patterns are favorable as they are thought to be conducive for better charge transport in organic semiconductors, which results in enhanced device performance. Intra­molecular charge transfer is evident from the shortening in the observed experimental bond lengths. The nitro­gen atoms (of the cyano groups) are involved in extensive short contacts, primarily through C—H⋯NC inter­actions with distances of 2.637 (17) Å.

The structure of (S)-5-(3-acetyl-5-chloro-2-ethoxy-6-fluorophenyl)-2-oxazolidinone, C13H13ClFNO4, at 100 K has monoclinic (P21) symmetry. The compound has a polymeric structure propagated by a screw axis parallel to the b axis with N—H⋯O hydrogen bonding. It is of inter­est with respect to efforts in the synthesis of a candidate anti­cancer drug, parsaclisib.

The structures of ten phosphane chalcogenide complexes of gold(III) halides, with general formula R13–nR2nPEAuX3 (R1 = t-butyl; R2 = i-propyl; n = 0 to 3; E = S or Se; X = Cl or Br) are presented. The eight possible chlorido derivatives are: 9a, n = 3, E = S; 10a, n = 2, E = S; 11a, n = 1, E = S; 12a, n = 0, E = S; 13a, n = 3, E = Se; 14a, n = 2, E = Se; 15a, n = 1, E = Se; and 16a, n = 0, E = Se, and the corresponding bromido derivatives are 9b–16b in the same order. Structures were obtained for 9a, 10a (and a second polymorph 10aa), 11a (and its deutero­chloro­form monosolvate 11aa), 12a (as its di­chloro­methane monosolvate), 14a, 15a (as its deutero­chloro­form monosolvate 15aa, in which the solvent mol­ecule is disordered over two positions), 9b, 11b, 13b and 15b. The structures of 11a, 15a, 11b and 15b form an isotypic set, and those of compounds 10aa and 14a form an isotypic pair. All structures have Z' = 1. The gold(III) centres show square-planar coordination geometry and the chalcogenide atoms show approximately tetra­hedral angles (except for the very wide angle in 12a, probably associated with the bulky t-butyl groups). The bond lengths at the gold atoms are lengthened with respect to the known gold(I) derivatives, and demonstrate a considerable trans influence of S and Se donor atoms on a trans Au—Cl bond. Each compound with an isopropyl group shows a short intra­molecular contact of the type C—Hmethine⋯Xcis; these may be regarded as intra­molecular ‘weak’ hydrogen bonds, and they determine the orientation of the AuX3 groups. The mol­ecular packing is analysed in terms of various short contacts such as weak hydrogen bonds C—H⋯X and contacts between the heavier atoms, such as X⋯X (9a, 10aa, 11aa, 15aa and 9b), S⋯S (10aa, 11a and 12a) and S⋯Cl (10a). The packing of the polymorphs 10a and 10aa is thus quite different. The solvent mol­ecules take part in C—H⋯Cl hydrogen bonds; for 15aa, a disordered solvent region at z ≃ 0 is observed. Structure 13b involves unusual inversion-symmetric dimers with Se⋯Au and Se⋯Br contacts, further connected by Br⋯Br contacts.

The title compound, C14H12N4O2·0.5HCl·H2O or H(C14H12N4O2)2+·Cl−·2H2O, arose from the unexpected cyclization of isonicotinoyl-N-phenyl hydrazine carbo­thio­amide catalysed by cobalt(II) acetate. The organic mol­ecule is almost planar and a symmetric N⋯H+⋯N hydrogen bond links two of them together, with the H atom lying on a crystallographic twofold axis. The extended structure features N—H⋯O and O—H⋯Cl hydrogen bonds, which generate [001] chains. Weak C—H⋯Cl inter­actions cross-link the chains. The chloride ion has site symmetry 2. The major contributions to the Hirshfeld surface are from H⋯H (47.1%), Cl⋯H/H⋯Cl (total 10.8%), O⋯H/H⋯O (7.4%) and N⋯H/H⋯N (6.7%) inter­actions.

A lutetium(III) complex based on the anion of the ligand dimethyl (2,2,2-tri­chloro­acet­yl)phospho­ramidate (HL) and tetra­phenylphosphonium, of composition PPh4[LuL4] (L = CAPh = carbacyl­amido­phosphate), or (C24H20)[Lu(C4H6Cl3NO4P)4], has been synthesized and structurally characterized. The X-ray diffraction study of the compound revealed that the lutetium ion is surrounded by four bis-chelating CAPh ligands, forming the complex anion [LuL4]− with a coordination number of 8[O] for LuIII, while PPh4+ serves as a counter-ion. The coordination geometry around the Lu3+ ion was determined to be a nearly perfect triangular dodeca­hedron. The complex crystallizes in the monoclinic crystal system, space group P21/c, with four mol­ecules in the unit cell. Weak hydrogen bonds O⋯HC(Ph), Cl⋯HC(Ph) and N⋯HC(Ph) are formed between the cations and anions. For a comparative study, HL-based structures were retrieved from the Cambridge Structural Database (CSD) and their geometries and conformations are discussed. A Hirshfeld surface analysis was also performed.

The asymmetric unit of the title compound, 2C31H28N2O4S·C2H6O, contains a parent mol­ecule and a half mol­ecule of ethanol solvent. The main compound stabilizes its mol­ecular conformation by forming a ring with an R12(7) motif with the ethanol solvent mol­ecule. In the crystal, mol­ecules are connected by C—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional network. In addition, C—H⋯π inter­actions also strengthen the mol­ecular packing.

In the crystal of the title compound, C18H14O10·2H2O, the arene rings of the biphenyl moiety are tilted at an angle of 24.3 (1)°, while the planes passing through the carboxyl groups are rotated at angles of 8.6 (1) and 7.7 (1)° out of the plane of the benzene ring to which they are attached. The crystal structure is essentially stabilized by O—H⋯O bonds. Here, the carboxyl groups of neighbouring host mol­ecules are connected by cyclic R22(8) synthons, leading to the formation of a three-dimensional network. The water mol­ecules in turn form helical supra­molecular strands running in the direction of the crystallographic c-axis (chain-like water clusters). The second H atom of each water mol­ecule provides a link to a meth­oxy O atom of the host mol­ecule. A Hirshfeld surface analysis was performed to qu­antify the contributions of the different inter­molecular inter­actions, indicating that the most important contributions to the crystal packing are from H⋯O/O⋯H (37.0%), H⋯H (26.3%), H⋯C/C⋯H (18.5%) and C⋯O/O⋯C (9.5%) inter­actions.

In the title mol­ecule, C21H23N3O3, the imidazolidine ring slightly deviates from planarity and the morpholine ring exhibits the chair conformation. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds form helical chains of mol­ecules extending parallel to the c axis that are connected by C—H⋯π(ring) inter­actions. A Hirshfeld surface analysis reveals that the most important contributions for the crystal packing are from H⋯H (55.2%), H⋯C/C⋯H (22.6%) and H⋯O/O⋯H (20.5%) inter­actions. The volume of the crystal voids and the percentage of free space were calculated to be 236.78 Å3 and 12.71%, respectively. Evaluation of the electrostatic, dispersion and total energy frameworks indicates that the stabilization is dominated by the nearly equal electrostatic and dispersion energy contributions. The DFT-optimized mol­ecular structure at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined mol­ecular structure in the solid state. Moreover, the HOMO–LUMO behaviour was elucidated to determine the energy gap.

Treatment of 3-(3,4-di­hydroxy­phen­yl)propenoic acid (caffeic acid or 3,4-di­hydroxy­cinnamic acid) with the alkali hydroxides MOH (M = Li, Na) in aqueous solution led to the formation of poly[aqua­[μ-3-(3,4-di­hydroxy­phen­yl)propenoato]lithium], [Li(C9H7O4)(H2O)]n, 1, and poly[aqua­[μ-3-(3,4-di­hydroxy­phen­yl)propenoato]sodium], [Na(C9H7O4)(H2O)]n, 2. The crystal structure of 1 consists of a lithium cation that is coordinated nearly tetra­hedrally by three carboxyl­ate oxygen atoms and a water mol­ecule. The carboxyl­ate groups adopt a μ3-κ3O:O':O' coordination mode that leads to a chain-like catenation of Li cations and carboxyl­ate units parallel to the b axis. Moreover, the lithium carboxyl­ate chains are connected by hydrogen bonds between water mol­ecules attached to lithium and catechol OH groups. The crystal structure of 2 shows a sevenfold coordination of the sodium cation by one water mol­ecule, two monodentately binding carboxyl­ate groups and four oxygen atoms from two catechol groups. The coordination polyhedra are linked by face- and edge-sharing into chains extending parallel to the b axis. The chains are inter­linked by the bridging 3-(3,4-di­hydroxy­phen­yl)propenoate units and by inter­molecular hydrogen bonds to form the tri-periodic network.

In the ten-membered 1,3,4,6-tetra­hydro-2H-pyrido[1,2-a]pyrimidine ring system of the title compound, C17H15N5, the 1,2-di­hydro­pyridine ring is essentially planar (r.m.s. deviation = 0.001 Å), while the 1,3-diazinane ring has a distorted twist-boat conformation. In the crystal, mol­ecules are linked by N—H⋯N and C—H⋯N hydrogen bonds, forming a three-dimensional network. In addition, C—H⋯π inter­actions form layers parallel to the (100) plane. Thus, crystal-structure cohesion is ensured. According to a Hirshfeld surface study, H⋯H (40.4%), N⋯H/H⋯N (28.6%) and C⋯H/H⋯C (24.1%) inter­actions are the most important contributors to the crystal packing.

N-Phenyl-2-(phenyl­sulfan­yl)acetamide, C14H13NOS, was synthesized and structurally characterized. In the crystal, N—H⋯O hydrogen bonding leads to the formation of chains of mol­ecules along the [100] direction. The chains are linked by C—H⋯π inter­actions, forming a three-dimensional network. The crystal studied was twinned by a twofold rotation around [100].

In the structure of the title compound, C22H22N4O4·C3H7NO·H2O, the entire tricyclic system is approximately planar except for the carbon atom bearing the two methyl groups; the meth­oxy­phenyl ring is approximately perpendicular to the tricycle. All seven potential hydrogen-bond donors take part in classical hydrogen bonds. The main mol­ecule and the DMF combine to form broad ribbons parallel to the a axis and roughly parallel to the ab plane; the water mol­ecules connect the residues in the third dimension.

In the title compound, C17H12N2O, the quinoxaline moiety shows deviations of 0.0288 (7) to −0.0370 (7) Å from the mean plane (r.m.s. deviation of fitted atoms = 0.0223 Å). In the crystal, corrugated layers two mol­ecules thick are formed by C—H⋯N hydrogen bonds and π-stacking inter­actions.

The structures of fourteen halochalcogenyl­phospho­nium tetra­halogen­ido­aurates(III), phosphane chalcogenide derivatives with general formula [R13–nR2nPEX][AuX4] (R1 = t-butyl; R2 = isopropyl; n = 0 to 3; E = S or Se; X = Cl or Br) are presented. The eight possible chlorido derivatives are: 17a, n = 3, E = S; 18a, n = 2, E = S; 19a, n = 1, E = S; 20a, n = 0, E = S; 21a, n = 3, E = Se; 22a, n = 2, E = Se; 23a, n = 1, E = Se; and 24a, n = 0, E = Se, and the corresponding bromido derivatives are 17b–24b in the same order. Structures were obtained for all compounds except for the tri-t-butyl derivatives 24a and 24b. Isotypy is observed for 18a/18b/22a/22b, 19a/23a, 17b/21b and 19b/23b. In eleven of the compounds, X⋯X contacts (mostly very short) are observed between the cation and anion, whereby the E—X⋯X groups are approximately linear and the X⋯X—Au angles approximately 90°. The exceptions are 17a, 19a and 23a, which instead display short E⋯X contacts. Bond lengths in the cations correspond to single bonds P—E and E—X. For each group with constant E and X, the P—E—X bond-angle values increase monotonically with the steric bulk of the alkyl groups. The packing is analysed in terms of E⋯X, X⋯X (some between anions alone), H⋯X and H⋯Au contacts. Even for isotypic compounds, some significant differences can be discerned.

Tri­chlorido­(4-methyl­piperidine)­gold(III), [AuCl3(C6H13N)], 1, crystallizes in Pbca with Z = 8. Tri­bromido­(4-methyl­piperidine)­gold(III), [AuBr3(C6H13N)], 2, crystallizes as two polymorphs, 2a in Pnma with Z = 4 (imposed mirror symmetry) and 2b, which is isotypic to 1. The Au—N bonds trans to Cl are somewhat shorter than those trans to Br, and the Au—Cl bonds trans to N are longer than those cis to N, whereas the Au—Br bonds trans to N are slightly shorter than the cis bonds. The methyl and AuX3 groups (X = halogen) occupy equatorial positions at the six-membered ring. The packing of all three structures involves chains of mol­ecules with offset stacking of the AuX3 moieties associated with short Au⋯X contacts; for 1 and 2b these are reinforced by N—H⋯X hydrogen bonds, whereas for 2a there are no classical hydrogen bonds and the chains are inter­connected by Br⋯Br contacts.

In the title compound, C20H17BrO5S, mol­ecules are connected by inter­molecular C—H⋯S hydrogen bonds with R22(10) ring motifs, forming ribbons along the b-axis direction. C—H⋯π inter­actions consolidate the ribbon structure while van der Waals forces between the ribbons ensure the cohesion of the crystal structure. According to a Hirshfeld surface analysis, H⋯H (40.5%), O⋯H/H⋯O (27.0%), C⋯H/H⋯C (13.9%) and Br⋯H/H⋯Br (11.7%) inter­actions are the most significant contributors to the crystal packing. The thio­phene ring and its adjacent di­carboxyl­ate group and the three adjacent carbon atoms of the central hexene ring to which they are attached were refined as disordered over two sets of sites having occupancies of 0.8378 (15) and 0.1622 (15). The thio­phene group is disordered by a rotation of 180° around one bond.

The asymmetric unit of the title compound, C25H18N6·H2O, comproses two mol­ecules (I and II), together with a water mol­ecule. The terminal phenyl groups attached to the methyl groups of the mol­ecules I and II do not overlap completely, but are approximately perpendicular. In the crystal, the mol­ecules are connected by N—H⋯N, C—H⋯N, O—H⋯N and N—H⋯O hydrogen bonds with each other directly and through water mol­ecules, forming layers parallel to the (001) plane. C—H⋯π inter­actions between these layers ensure the cohesion of the crystal structure. A Hirshfeld surface analysis indicates that H⋯H (39.1% for mol­ecule I; 40.0% for mol­ecule II), C⋯H/H⋯C (26.6% for mol­ecule I and 25.8% for mol­ecule II) and N⋯H/H⋯N (24.3% for mol­ecules I and II) inter­actions are the most important contributors to the crystal packing.

The title copper(II) complex, [Cu(C18H19N3O3)(C3H4N2)], consists of a tridentate ligand synthesized from l-leucine and azo­benzene-salicyl­aldehyde. One imidazole mol­ecule is additionally coordinated to the copper(II) ion in the equatorial plane. The crystal structure features N—H⋯O hydrogen bonds. A Hirshfeld surface analysis indicates that the most important contributions to the packing are from H⋯H (52.0%) and C⋯H/H⋯C (17.9%) contacts.

The structure of the title compound, C23H21BrN4O, contains two independent mol­ecules connected by hydrogen bonds of the type Namide—H⋯N≡C to form a dimer. The configuration at the exocyclic C=C double bond is E. The mol­ecules are roughly planar except for the isopropyl groups. There are minor differences in the orientations of these groups and the phenyl rings at N1. The dimers are further linked by ‘weak’ hydrogen bonds, two each of the types Hphen­yl⋯O=C (H⋯O = 2.50, 2.51 Å) and Hphen­yl⋯Br (H⋯Br = 2.89, 2.91 Å), to form ribbons parallel to the b and c axes, respectively. The studied crystal was a non-merohedral twin.

The title compound, C12H15N3O2S, adopts an E configuration with respect to the C=N bond. The propionate group adopts an anti­periplanar (ap) conformation. There are short intra­molecular N—H⋯N and C—H⋯O contacts, forming S(5) and S(6) ring motifs, respectively. In the crystal, mol­ecules are connected into ribbons extending parallel to [010] by pairs of N—H⋯S inter­actions, forming rings with R22(8) graph-set motifs, and by pairs of C—H⋯S inter­actions, where rings with the graph-set motif R21(7) are observed. The O atom of the carbonyl group is disordered over two positions, with a refined occupancy ratio of 0.27 (2):0.73 (2). The studied crystal consisted of two domains.

In the title compound, C24H21NO3S, the cyclopentene ring adopts an envelope conformation. In the crystal, mol­ecules are linked by C—H⋯π inter­actions, forming ribbons along the a axis. Inter­molecular C—H⋯O hydrogen bonds connect these ribbons to each other, forming layers parallel to the (0overline{1}1) plane. The mol­ecular packing is strengthened by van der Waals inter­actions between the layers. The inter­molecular contacts were qu­anti­fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 46.0%, C⋯H/H⋯C 21.1%, O⋯H/H⋯O 20.6% and S⋯H/H⋯S 9.0%.

In the title mol­ecule, C21H17N3O2, the five-membered ring is slightly ruffled and dihedral angles between the pendant six-membered rings and the central, five-membered ring vary between 50.78 (4) and 86.78 (10)°. The exocyclic nitro­gen lone pair is involved in conjugated π bonding to the five-membered ring. In the crystal, a layered structure is generated by O—H⋯N and N—H⋯O hydrogen bonds plus C—H⋯π(ring) and weak π-stacking inter­actions.

The title compound, C12H10N2O3, was obtained by the de­acetyl­ation reaction of 1-(6-amino-5-nitro­naphthalen-2-yl)ethanone in a concentrated sulfuric acid methanol solution. The mol­ecule comprises a naphthalene ring system bearing an acetyl group (C-3), an amino group (C-7), and a nitro group (C-8). In the crystal, the mol­ecules are assembled into a two-dimensional network by N⋯H/H⋯N and O⋯H/H⋯O hydrogen-bonding inter­actions. n–π and π–π stacking inter­actions are the dominant inter­actions in the three-dimensional crystal packing. Hirshfeld surface analysis indicates that the most important contributions are from O⋯H/H⋯O (34.9%), H⋯H (33.7%), and C⋯H/H⋯C (11.0%) contacts. The energies of the frontier mol­ecular orbitals were computed using density functional theory (DFT) calculations at the B3LYP-D3BJ/def2-TZVP level of theory and the LUMO–HOMO energy gap of the mol­ecule is 3.765 eV.

The new palladium(II) complex, [Pd(C16H16N4O3)2](CF3COO)2·2CF3COOH, crystallizes in the triclinic space group Poverline{1} with the asymmetric unit containing half the cation (PdII site symmetry Ci), one tri­fluoro­actetate anion and one co-crystallized tri­fluoro­acetic acid mol­ecule. Two neutral chelating 2-[5-(3,4,5-tri­meth­oxy­phen­yl)-4H-1,2,4-triazol-3-yl]pyridine ligands coordinate to the PdII ion through the triazole-N and pyridine-N atoms in a distorted trans-PdN4 square-planar configuration [Pd—N 1.991 (2), 2.037 (2) Å; cis N—Pd—N 79.65 (8), 100.35 (8)°]. The complex cation is quite planar, except for the methoxo groups (δ = 0.117 Å for one of the C atoms). The planar configuration is supported by two intra­molecular C—H⋯N hydrogen bonds. In the crystal, the π–π-stacked cations are arranged in sheets parallel to the ab plane that are flanked on both sides by the tri­fluoro­acetic acid–tri­fluoro­acetate anion pairs. Apart from classical N/O—H⋯O hydrogen-bonding inter­actions, weak C—H⋯F/N/O contacts consolidate the three-dimensional architecture. Both tri­fluoro­acetic moieties were found to be disordered over two resolvable positions with a refined occupancy ratio of 0.587 (1):0.413 (17) and 0.530 (6):0.470 (6) for the protonated and deprotonated forms, respectively.

In the title compound, C15H13NO3S, the mol­ecular conformation is stable with the intra­molecular O—H⋯O hydrogen bond forming a S(7) ring motif. In the crystal, mol­ecules are connected by C—H⋯O hydrogen bonds, forming C(8) chains running along the a-axis direction. Cohesion of the packing is provided by weak van der Waals inter­actions between the chains. A Hirshfeld surface analysis was undertaken to investigate and qu­antify the inter­molecular inter­actions. The thio­phene ring is disordered in a 0.9466 (17):0.0534 (17) ratio over two positions rotated by 180°.

The title compound, C12H16N2O, is a hy­droxy-substituted mono­amine alkaloid, and the primary metabolite of the naturally occurring psychedelic compound psilocybin. Crystalline forms of psilocin are known, but their characterization by single-crystal structure analysis is limited. Herein, two anhydrous polymorphic forms (I and II) of psilocin are described. The crystal structure of polymorphic Form I, in space group P21/c, was first reported in 1974. Along with the redeterm­ination to modern standards and unambiguous location of the acidic H atom and variable-temperature single-crystal unit-cell determinations for Form I, the Form II polymorph of the title compound, which crystallizes in the monoclinic space group P21/n, is described for the first time. The psilocin mol­ecules are present in both forms in their phenol–amine tautomeric forms (not resolved in the 1974 report). The mol­ecules in Forms I and II, however, feature different conformations of their N,N-dimethyl ethyl­ene substituent, with the N—C—C—C link in Form I being trans and in Form II being gauche, allowing the latter to bend back to the hydroxyl group of the same mol­ecule, leading to the formation of a strong intra­molecular O—H⋯N hydrogen bond between the hydroxyl moiety and ethyl­amino-nitro­gen group. In the extended structure of Form II, the mol­ecules form one-dimensional strands through N—H⋯O hydrogen bonds from the indole group to the oxygen atom of the hydroxyl moiety of an adjacent mol­ecule. Form II exhibits whole-mol­ecule disorder due to a pseudo-mirror operation, with an occupancy ratio of 0.689 (5):0.311 (5) for the two components. In contrast, Form I does not feature intra­molecular hydrogen bonds but forms a layered structure through inter­molecular N—H⋯O and O—H⋯N hydrogen bonds.

The reaction of lithium hexa­methyl­disilyl­amide, [Li{N(Si(CH3)3)2}] (LiHMDS), with 4,4-dimethyl-2-phenyl-2-oxazoline (Phox, C11H13NO) in hexane produced colourless crystals of bis­(4,4-dimethyl-2-phenyl-2-oxazoline-κN)(hexa­methyl­disilyl­amido-κN)lithium, [Li(C6H18NSi2)(C11H13NO)2] or [Li{N(Si(CH3)3)2}(Phox)2] in high yield (89%). Despite the 1:1 proportion of the starting materials in the reaction mixture, the product formed with a 1:2 amide:oxazoline ratio. In the unit cell of the C2/c space group, the neutral mol­ecules lie on twofold rotation axes coinciding with the Li—N(amide) bonds. The lithium(I) centre adopts a trigonal–planar coordination geometry with three nitro­gen donor atoms, one from the HMDS anion and two from the oxazolines. All ligands are monodentate. In the phenyl­oxazoline units, the dihedral angle defined by the five-membered heterocyclic rings is 35.81 (5)°, while the phenyl substituents are approximately face-to-face, separated by 3.908 (5) Å. In the amide, the methyl groups assume a nearly eclipsed arrangement to minimize steric repulsion with the analogous substituents on the oxazoline rings. The non-covalent inter­actions in the solid-state structure of [Li{N(Si(CH3)3)2}(Phox)2] were assessed by Hirshfeld surface analysis and fingerprint plots. This new compound is attractive for catalysis due to its unique structural features.

In the title compound, C31H24N4O2, the di­hydro­quinoxaline units are both essentially planar with the dihedral angle between their mean planes being 64.82 (4)°. The attached phenyl rings differ significantly in their rotational orientations with respect to the di­hydro­quinoxaline planes. In the crystal, one set of C—H⋯O hydrogen bonds form chains along the b-axis direction, which are connected in pairs by a second set of C—H⋯O hydrogen bonds. Two sets of π-stacking inter­actions and C—H⋯π(ring) inter­actions join the double chains into the final three-dimensional structure.

The synthesis, crystallization and characterization of a tri­fluoro­methane­sulfonate salt of 5,10,15,20-tetra­kis­(1-benzyl­pyridin-1-ium-4-yl)-21H,23H-por­phy­rin, C68H54N84+·4CF3SO3−·4H2O, 1·OTf, are reported in this work. The reaction between 5,10,15,20-tetra­kis­(pyridin-4-yl)-21H,23H-porphyrin and benzyl bromide in the presence of 0.1 equiv. of Ca(OH)2 in CH3CN under reflux with an N2 atmosphere and subsequent treatment with silver tri­fluoro­methane­sulfonate (AgOTf) salt produced a red–brown solution. This reaction mixture was filtered and the solvent was allowed to evaporate at room temperature for 3 d to give 1·OTf. Crystal structure determination by single-crystal X-ray diffraction (SCXD) revealed that 1·OTf crystallizes in the space group P21/c. The asymmetric unit contains half a porphyrin mol­ecule, two tri­fluoro­methane­sulfonate anions and two water mol­ecules of crystallization. The macrocycle of tetra­pyrrole moieties is planar and unexpectedly it has coordinated CaII ions in occupational disorder. This CaII ion has only 10% occupancy (C72H61.80Ca0.10F12N8O16S4). The pyridinium rings bonded to methyl­ene groups from porphyrin are located in two different arrangements in almost orthogonal positions between the plane formed by the porphyrin and the pyridinium rings. The crystal structure features cation⋯π inter­actions between the CaII atom and the π-system of the phenyl ring of neighboring mol­ecules. Both tri­fluoro­methane­sulfonate anions are found at the periphery of 1, forming hydrogen bonds with water mol­ecules.

Title compound 1Ni, [Ni(C46H32N4O2)], a secochlorin nickel complex, was prepared by diol cleavage of a precursor trans-di­hydroxy­dimethyl­chlorin. Two crystallographically independent mol­ecules in the structure are related by pseudo-A lattice centering, with mol­ecules differing mainly by a rotation of one of the acetyls and an adjacent phenyl groups. The two mol­ecules have virtually identical conformations characterized by noticeable in-plane deformation in the A1g mode and a prominent out-of-plane deformation in the B1u (ruffling) mode. Directional inter­actions between mol­ecules are scarce, limited to just a few C—H⋯O contacts, and inter­molecular inter­actions are mostly dispersive in nature.

In the title compound, C19H17NO5S, the cyclo­hexene ring adopts nearly an envelope conformation. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds, forming a three-dimensional network. In addition, C—H⋯π inter­actions connect the mol­ecules by forming layers parallel to the (010) plane. According to the Hirshfeld surface analysis, H⋯H (36.9%), O⋯H/H⋯O (31.0%), C⋯H/H⋯C (18.9%) and S⋯H/H⋯S (7.9%) inter­actions are the most significant contributors to the crystal packing.

Three new 1H-indole derivatives, namely, 2-(bromo­meth­yl)-3-methyl-1-(phenyl­sulfon­yl)-1H-indole, C16H14BrNO2S, (I), 2-[(E)-2-(2-bromo-5-meth­oxy­phen­yl)ethen­yl]-3-methyl-1-(phenyl­sulfon­yl)-1H-indole, C24H20BrNO3S, (II), and 2-[(E)-2-(2-bromo­phen­yl)ethen­yl]-3-methyl-1-(phenyl­sulfon­yl)-1H-indole, C23H18BrNO2S, (III), exhibit nearly orthogonal orientations of their indole ring systems and sulfonyl-bound phenyl rings. Such conformations are favourable for inter­molecular bonding involving sets of slipped π–π inter­actions between the indole systems and mutual C—H⋯π hydrogen bonds, with the generation of two-dimensional monoperiodic patterns. The latter are found in all three structures, in the form of supra­molecular columns with every pair of successive mol­ecules related by inversion. The crystal packing of the compounds is additionally stabilized by weaker slipped π–π inter­actions between the outer phenyl rings (in II and III) and by weak C—H⋯O, C—H⋯Br and C—H⋯π hydrogen bonds. The structural significance of the different kinds of inter­actions agree with the results of a Hirshfeld surface analysis and the calculated inter­action energies. In particular, the largest inter­action energies (up to −60.8 kJ mol−1) are associated with pairing of anti­parallel indole systems, while the energetics of weak hydrogen bonds and phenyl π–π inter­actions are comparable and account for 13–34 kJ mol−1.