The title compound, [Mn(S4)(C8H20N4)], was accidentally obtained by the hydro­thermal reaction of Mn(ClO4)2·6H2O, cyclen (cyclen = 1,4,7,10-tetra­aza­cyclo­dodeca­ne) and Na3SbS4·9H2O in water at 413 K, indicating that polysulfide anions might represent inter­mediates in the synthesis of thio­metallate compounds using Na3SbS4·9H2O as a reactant. X-ray powder diffraction proves that the sample is slightly contaminated with NaSb(OH)6 and an unknown crystalline phase. The crystal investigated was twinned with a twofold rotation axis as the twin element, and therefore a twin refinement using data in HKLF-5 format was performed. The asymmetric unit of the title compound consists of one MnII cation, one [S4]2− anion and one cyclen ligand in general positions. The MnII cation is sixfold coordinated by two cis-S atoms of the [S4]2− anions, as well as four N atoms of the cyclen ligand within an irregular coordination. The complexes are linked via pairs of N—H⋯S hydrogen bonds into chains, which are further linked into layers by additional N—H⋯S hydrogen bonding. These layers are connected into a three-dimensional network by inter­molecular N—H⋯S and C—H⋯S hydrogen bonding. It is noted that only one similar complex with MnII is reported in the literature.

The title crystal structure is assembled from the superposition of two mol­ecular structures, (E)-1-(5-chloro­thio­phen-2-yl)-3-(3-methyl­thio­phen-2-yl)prop-2-en-1-one, C12H9ClOS2 (93%), and (Z)-1-(5-chloro­thio­phen-2-yl)-3-(3-methyl­thio­phen-2-yl)prop-1-en-1-ol, C12H11ClOS2 (7%), 0.93C12H9ClOS2·0.07C12H11ClOS2. Both were obtained from the reaction of 3-methyl­thio­phene-2-carbaldehyde and 1-(5-chloro­thio­phen-2-yl)ethanone. In the extended structure of the major chalcone component, mol­ecules are linked by a combination of C—H⋯O/S, Cl⋯Cl, Cl⋯π and π–π inter­actions, leading to a compact three-dimensional supra­molecular assembly.

The asymmetric unit of the title compound, C10H11NO4, which was synthesized via nitration reaction of eugenol (4-allyl-2-meth­oxy­phenol) with a mixture of nitric acid and sulfuric acid, consists of three independent mol­ecules of similar geometry. Each mol­ecule displays an intra­molecular hydrogen bond involving the hydroxide and the nitro group forming an S(6) motif. The crystal cohesion is ensured by inter­molecular C—H⋯O hydrogen bonds in addition to π–π stacking inter­actions between the aromatic rings [centroid–centroid distances = 3.6583 (17)–4.0624 (16) Å]. The Hirshfeld surface analysis and the two-dimensional fingerprint plots show that H⋯H (39.6%), O⋯H/H⋯O (37.7%), C⋯H/H⋯C (12.5%) and C⋯C (4%) are the most important contributors towards the crystal packing.

The title compound, C15H14N2O2, consists of pyrrole and benzodiazepine units linked to a propargyl moiety, where the pyrrole and diazepine rings adopt half-chair and boat conformations, respectively. The absolute configuration was assigned on the the basis of l-proline, which was used in the synthesis of benzodiazepine. In the crystal, weak C—HBnz⋯ODiazp and C—HProprg⋯ODiazp (Bnz = benzene, Diazp = diazepine and Proprg = proparg­yl) hydrogen bonds link the mol­ecules into two-dimensional networks parallel to the bc plane, enclosing R44(28) ring motifs, with the networks forming oblique stacks along the a-axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.8%), H⋯C/C⋯H (25.7%) and H⋯O/O⋯H (20.1%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—H⋯O hydrogen-bond energies are 38.8 (for C—HBnz⋯ODiazp) and 27.1 (for C—HProprg⋯ODiazp) kJ mol−1. Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

In the title compound, C10H8N8·2H2O or H2bmtz·2H2O [bmtz = 3,6-bis­(2'-pyrimid­yl)-1,2,4,5-tetra­zine], the asymmetric unit consists of one-half mol­ecule of H2bmtz and one water mol­ecule, the whole H2bmtz mol­ecule being generated by a crystallographic twofold rotation axis passing through the middle point of the 1,4-di­hydro-1,2,4,5-tetra­zine moiety. In the crystal, N—H⋯O, N—H⋯N, O—H⋯O hydrogen bonds and aromatic π–π stacking inter­actions link the components into a three-dimensional supra­molecular network. Hirshfeld surface analysis was used to further investigate the inter­molecular inter­actions in the crystal structure.

In the title mol­ecular salt, 1,3-dimethyl-2,6-dioxo-2,3,6,7-tetra­hydro-1H-purin-9-ium aqua­tri­chlorido­zincate(II), (C7H9N4O2)[ZnCl3(H2O)], the fused ring system of the cation is close to planar, with the largest deviation from the mean plane being 0.037 (3) Å. In the complex anion, the ZnII cation is coordinated by three chloride ions and one oxygen atom from the water ligand in a distorted tetra­hedral geometry. In the crystal, inversion dimers between pairs of cations linked by pairwise N—H⋯O hydrogen bonds generate R22(10) rings. The anions are linked into dimers by pairs of O—H⋯Cl hydrogen bonds and the respective dimers are linked by O—H⋯O and N—H⋯Cl hydrogen bonds. Together, these generate a three-dimensional supra­molecular network. Hirshfeld surfaces were generated to gain further insight into the packing.

Crystal structures are reported for N-(4-meth­oxy­phen­yl)piperazine (MeOPP), (I), and for its 3,5-di­nitro­benzoate, 2,4,6-tri­nitro­phenolate (picrate) and 4-amino­benzoate salts, (II)–(IV), the last of which crystallizes as a monohydrate. In MeOPP, C11H16N2O, (I), the 4-meth­oxy­phenyl group is nearly planar and it occupies an equatorial site on the piperazine ring: the mol­ecules are linked into simple C(10) chains by N—H⋯O hydrogen bonds. In each of the salts, i.e., C11H17N2O+·C7H3N2O6−, (II), C11H17N2O+·C6H2N3O7−, (III), and C11H17N2O+·C7H6NO2−·H2O, (IV), the effectively planar 4-meth­oxy­phenyl substituent again occupies an equatorial site on the piperazine ring. In (II), two of the nitro groups are disordered over two sets of atomic sites and the bond distances in the anion indicate considerable delocalization of the negative charge over the C atoms of the ring. The ions in (II) are linked by two N—H⋯O hydrogen bonds to form a cyclic, centrosymmetric four-ion aggregate; those in (III) are linked by a combination of N—H⋯O and C—H⋯π(arene) hydrogen bonds to form sheets; and the components of (IV) are linked by N—H⋯O, O—H⋯O and C—H⋯π(arene) hydrogen bonds to form a three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

In the title hydrated complex, [Co(C15H10ClN3)2]Cl2·4H2O, the complete dication is generated by overline{4} symmetry. The CoN6 moiety shows distortion from regular octa­hedral geometry with the trans bond angles of two N—Co—N units being 160.62 (9)°. In the crystal, O—H⋯Cl and C—H⋯O inter­actions link the components into (001) sheets. The title compound exhibits blue-light emission, as indicated by photoluminescence data, and a HOMO–LUMO energy separation of 2.23 eV was obtained from its diffuse reflectance spectrum.

The redetermined structure [for the previous study, see: Godfrey & Waters (1975). Cryst. Struct. Commun. 4, 5–8] of ammonium μ-oxido-μ-[1,5,6-tri­hydroxy­hexane-2,3,4-tris­(olato)]bis­[dioxidomolybdenum(V)] monohydrate, NH4[Mo2(C6H11O6)O5]·H2O, was obtained from an attempt to prepare a glutamic acid complex from the [Co2Mo10H4O38]6− anion. Subsequent study indicated the complex arose from a substantial impurity of mannitol in the glutamic acid sample used. All hydrogen atoms have been located in the present study and the packing displays N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds. A Hirshfeld surface analysis was also performed.

In the title compound, C9H10ClNOS, the amide functional group –C(=O)NH– adopts a trans conformation with the four atoms nearly coplanar. This conformation promotes the formation of a C(4) hydrogen-bonded chain propagating along the [010] direction. The central part of the mol­ecule, including the six-membered ring, the S and N atoms, is fairly planar (r.m.s. deviation of 0.014). The terminal methyl group and the C(=O)CH2 group are slightly deviating out-of-plane while the terminal Cl atom is almost in-plane. Hirshfeld surface analysis of the title compound suggests that the most significant contacts in the crystal are H⋯H, H⋯Cl/Cl⋯H, H⋯C/C⋯H, H⋯O/O⋯H and H⋯S/S⋯H. π–π inter­actions between inversion-related mol­ecules also contribute to the crystal packing. DFT calculations have been performed to optimize the structure of the title compound using the CAM-B3LYP functional and the 6–311 G(d,p) basis set. The theoretical absorption spectrum of the title compound was calculated using the TD–DFT method. The analysis of frontier orbitals revealed that the π–π* electronic transition was the major contributor to the absorption peak in the electronic spectrum.

A one-dimensional nickel(II) coordination polymer with the mixed ligands 6-fluoro­nicotinate (6-Fnic) and 4,4'-bi­pyridine (4,4'-bpy), namely, catena-poly[[di­aqua­bis­(6-fluoro­pyridine-3-carboxyl­ato-κO)nickel(II)]-μ-4,4'-bi­pyri­dine-κ2N:N'] trihydrate], {[Ni(6-Fnic)2(4,4'-bpy)(H2O)2]·3H2O}n, (1), was prepared by the reaction of nickel(II) sulfate hepta­hydrate, 6-fluoro­nicotinic acid (C6H4FNO2) and 4,4'-bi­pyridine (C10H8N2) in a mixture of water and ethanol. The nickel(II) ion in 1 is octa­hedrally coordinated by the O atoms of two water mol­ecules, two O atoms from O-monodentate 6-fluoro­nicotinate ligands and two N atoms from bridging 4,4'-bi­pyridine ligands, forming a trans isomer. The bridging 4,4'-bi­pyridine ligands connect symmetry-related nickel(II) ions into infinite one-dimensional polymeric chains running in the [1overline{1}0] direction. In the extended structure of 1, the polymeric chains and lattice water mol­ecules are connected into a three-dimensional hydrogen-bonded network via strong O—H⋯O and O—H⋯N hydrogen bonds, leading to the formation of distinct hydrogen-bond ring motifs: octa­meric R88(24) and hexa­meric R86(16) loops.

The syntheses and crystal structures of three mol­ecular salts of protonated 3,4-di­amino­benzoic acid, viz. 2-amino-5-carb­oxy­anilinium chloride, C7H9N2O2+·Cl−, (I), 2-amino-5-carb­oxy­anilinium bromide, C7H9N2O2+·Br−, (II), and 2-amino-5-carb­oxy­anilinium nitrate monohydrate, C7H9N2O2+·NO3−·H2O, (III), are described. The cation is protonated at the meta-N atom (with respect to the carb­oxy group) in each case. In the crystal of (I), carb­oxy­lic acid inversion dimers linked by pairwise O—H⋯O hydrogen bonds are seen and each N—H group forms a hydrogen bond to a chloride ion to result in (100) undulating layers of chloride ions bridged by the inversion dimers into a three-dimensional network. The extended structure of (II) features O—H⋯Br, N—H⋯Br and N—H⋯O hydrogen bonds: the last of these generates C(7) chains of cations. Overall, the packing in (II) features undulating (100) sheets of bromide ions alternating with the organic cations. Inter­molecular inter­actions in the crystal of (III) include O—H⋯O, O—H⋯(O,O), N—H⋯O, N—H⋯N and O—H⋯N links. The cations are linked into (001) sheets, and the nitrate ions and water mol­ecules form undulating chains. Taken together, alternating (001) slabs of organic cations plus anions/water mol­ecules result. Hirshfeld surfaces and fingerprint plots were generated to give further insight into the inter­molecular inter­actions in these structures. The crystal used for the data collection of (II) was twinned by rotation about [100] in reciprocal space in a 0.4896 (15):0.5104 (15) ratio.

The two new pyrazine­ophanes, 5,7-di­hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine, C8H8N2S2, L1, and 3,4,8,10,11,13-hexa­hydro-1H,6H-bis­([1,4]di­thio­cino)[6,7-b:6',7'-e]pyrazine, C12H16N2S4, L2, both crystallize with half a mol­ecule in the asymmetric unit; the whole mol­ecules are generated by inversion symmetry. The mol­ecule of L1, which is planar (r.m.s. deviation = 0.008 Å), consists of two sulfur atoms linked by a rigid tetra-2,3,5,6-methyl­ene­pyrazine unit, forming planar five-membered rings. The mol­ecule of L2 is step-shaped and consists of two S–CH2–CH2–S chains linked by the central rigid tetra-2,3,5,6-methyl­ene­pyrazine unit, forming eight-membered rings that have twist-boat-chair con­fig­urations. In the crystals of both compounds, there are no significant inter­molecular inter­actions present. The reaction of L1 with silver nitrate leads to the formation of a two-dimensional coordination polymer, poly[(μ-5,7-di­hydro-1H,3H-dithieno[3,4-b;3',4'-e]pyrazine-κ2S:S')(μ-nitrato-κ2O:O')silver(I)], [Ag(NO3)(C8H8N2S2)]n, (I), with the nitrato anion bridging two equivalent silver atoms. The central pyrazine ring is situated about an inversion center and the silver atom lies on a twofold rotation axis that bis­ects the nitrato anion. The silver atom has a fourfold AgO2S2 coordination sphere with a distorted shape. The reaction of L2 with silver nitrate also leads to the formation of a two-dimensional coordination polymer, poly[[μ33,4,8,10,11,13-hexa­hydro-1H,6H-bis­([1,4]di­thio­cino)[6,7-b;6',7'-e]pyrazine-κ3S:S':S''](nitrato-κO)silver(I)], [Ag(NO3)(C12H16N2S4)]n, (II), with the nitrate anion coordinating in a monodentate manner to the silver atom. The silver atom has a fourfold AgOS3 coordination sphere with a distorted shape. In the crystals of both complexes, the networks are linked by C—H⋯O hydrogen bonds, forming supra­molecular frameworks. There are additional C—H⋯S contacts present in the supra­molecular framework of II.

The title compounds, [Mo(C5H5)(COCH3)(C6H12N3P)(CO)2], (1), and [Mo(C5H5)(COCH3)(C9H16N3O2P)(C6H5)2))(CO)2], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C5H5)(CO)3(CH3)]. The mol­ecular structures of these complexes are quite similar, exhibiting a four-legged piano-stool geometry with trans-disposed carbonyl ligands. The extended structures of complexes (1) and (2) differ substanti­ally. For complex (1), the molybdenum acetyl unit plays a dominant role in the organization of the extended structure, joining the mol­ecules into centrosymmetrical dimers through C—H⋯O inter­actions with a cyclo­penta­dienyl ligand of a neighboring mol­ecule, and these dimers are linked into layers parallel to (100) by C—H⋯O inter­actions between the molybdenum acetyl and the cyclo­penta­dienyl ligand of another neighbor. The extended structure of (2) is dominated by C—H⋯O inter­actions involving the carbonyl groups of the acetamide groups of the DAPTA ligand, which join the mol­ecules into centrosymmetrical dimers and link them into chains along [010]. Additional C—H⋯O inter­actions between the molybdenum acetyl oxygen atom and an acetamide methyl group join the chains into layers parallel to (101).

Two salts were prepared by methyl­ation of the respective imidazoline-2-thione at the sulfur atom, using Meerwein's salt (tri­methyl­oxonium tetra­fluorido­borate) in CH2Cl2. 1,3-Dimeth­oxy-2-(methyl­sulfan­yl)imidazolium tetra­fluorido­borate (1), C6H11N2O2S+·BF4−, displays a syn conformation of its two meth­oxy groups relative to each other whereas the two benz­yloxy groups present in 1,3-dibenz­yloxy-2-(methyl­sulfan­yl)imidazolium tetra­fluorido­borate (2), C18H19N2O2S+·BF4−, adopt an anti conformation. In the mol­ecules of 1 and 2, the methyl­sulfanyl group is rotated out of the plane of the respective heterocyclic ring. In both crystal structures, inter­molecular inter­actions are dominated by C—H⋯F—B contacts, leading to three-dimensional networks. The tetra­fluorido­borate counter-ion of 2 is disordered over three orientations (occupancy ratio 0.42:0.34:0.24), which are related by rotation about one of the B—F bonds.

The asymmetric unit of the title compound, C5H7N2O+·C4H4NO4S−, contains one cation and one anion. The 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxa­thia­zin-3-ide anion adopts an envelope conformation with the S atom as the flap. In the crystal, the anions and cations are held together by N—H⋯O, N—H⋯N, O—H⋯O and C—H⋯O hydrogen bonds, thus forming a three-dimensional structure. The Hirshfeld surface analysis and fingerprint plots reveal that the crystal packing is dominated by O⋯H/H⋯O (43.1%) and H⋯H (24.2%) contacts.

The title compound, C17H12O4, was synthesized from the dye alizarin. The dihedral angle between the mean plane of the anthra­quinone ring system (r.m.s. deviation = 0.039 Å) and the dioxepine ring is 16.29 (8)°. In the crystal, the mol­ecules are linked by C—H⋯O hydrogen bonds, forming sheets lying parallel to the ab plane. The sheets are connected through π–π and C=O⋯π inter­actions to generate a three-dimensional supra­molecular network. Hirshfeld surface analysis was used to investigate inter­molecular inter­actions in the solid-state: the most important contributions are from H⋯H (43.0%), H⋯O/O⋯H (27%), H⋯C/C⋯H (13.8%) and C⋯C (12.4%) contacts.

The solid-state structures of the naturally occurring psychoactive tryptamine norpsilocin {4-hy­droxy-N-methyl­tryptamine (4-HO-NMT); systematic name: 3-[2-(methyl­amino)­eth­yl]-1H-indol-4-ol}, C11H14N2O, and its fumarate salt (4-hy­droxy-N-methyl­tryptammonium fumarate; systematic name: bis­{[2-(4-hy­droxy-1H-indol-3-yl)eth­yl]methyl­aza­nium} but-2-enedioate), C11H15N2O+·0.5C4H2O42−, are reported. The freebase of 4-HO-NMT has a single mol­ecule in the asymmetric unit joined together by N—H⋯O and O—H⋯O hydrogen bonds in a two-dimensional network parallel to the (100) plane. The ethyl­amine arm of the tryptamine is modeled as a two-component disorder with a 0.895 (3) to 0.105 (3) occupancy ratio. The fumarate salt of 4-HO-NMT crystallizes with a tryptammonium cation and one half of a fumarate dianion in the asymmetric unit. The ions are joined together by N—H⋯O and O—H⋯O hydrogen bonds to form a three-dimensional framework, as well as π–π stacking between the six-membered rings of inversion-related indoles (symmetry operation: 2 − x, 1 − y, 2 – z).

In the fused ring system of the title compound, C32H37NO4, the central di­hydro­pyridine ring adopts a flattened boat conformation, the mean and maximum deviations of the di­hydro­pyridine ring being 0.1429 (2) and 0.2621 (2) Å, respectively. The two cyclo­hexenone rings adopt envelope conformations with the tetra­substituted C atoms as flap atoms. The benzene and phenyl rings form dihedral angles of 85.81 (2) and 88.90 (2)°, respectively, with the mean plane of the di­hydro­pyridine ring. In the crystal, mol­ecules are linked via an O—H⋯O hydrogen bond, forming a helical chain along the b-axis direction. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (65.2%), O⋯H/H⋯O (18.8%) and C⋯H/H⋯C (13.9%) contacts. Quantum chemical calculations for the frontier mol­ecular orbitals were undertake to determine the chemical reactivity of the title compound.

The title compound, C19H16ClNO3S, consists of chloro­phenyl methyl­idene and di­hydro­benzo­thia­zine units linked to an acetate moiety, where the thia­zine ring adopts a screw-boat conformation. In the crystal, two sets of weak C—HPh⋯ODbt (Ph = phenyl and Dbt = di­hydro­benzo­thia­zine) hydrogen bonds form layers of mol­ecules parallel to the bc plane. The layers stack along the a-axis direction with inter­calation of the ester chains. The crystal studied was a two component twin with a refined BASF of 0.34961 (5). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (37.5%), H⋯C/C⋯H (24.6%) and H⋯O/O⋯H (16.7%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—HPh⋯ODbt hydrogen bond energies are 38.3 and 30.3 kJ mol−1. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. Moreover, the anti­bacterial activity of the title compound has been evaluated against gram-positive and gram-negative bacteria.

A 6-chloro­nicotinate (6-Clnic) salt of a one-dimensional cationic nickel(II) coordination polymer with 4,4'-bi­pyridine (4,4'-bpy), namely, catena-poly[[[tetra­aqua­nickel(II)]-μ-4,4'-bi­pyridine-κ2N:N'] bis­(6-chloro­nicotinate) tetra­hydrate], {[Ni(C10H8N2)(H2O)4](C6H3ClNO2)2·4H2O}n or {[Ni(4,4'-bpy)(H2O)4](6-Clnic)2·4H2O}n, (1), was prepared by the reaction of nickel(II) sulfate hepta­hydrate, 6-chloro­nicotinic acid and 4,4'-bi­pyridine in a mixture of water and ethanol. The mol­ecular structure of 1 comprises a one-dimensional polymeric {[Ni(4,4'-bpy)(H2O)4]2+}n cation, two 6-chloro­nicotinate anions and four water mol­ecules of crystallization per repeating polymeric unit. The nickel(II) ion in the polymeric cation is octa­hedrally coordinated by four water mol­ecule O atoms and by two 4,4'-bi­pyridine N atoms in the trans position. The 4,4'-bi­pyridine ligands act as bridges and, thus, connect the symmetry-related nickel(II) ions into an infinite one-dimensional polymeric chain extending along the b-axis direction. In the extended structure of 1, the polymeric chains of {[Ni(4,4'-bpy)(H2O)4]2+}n, the 6-chloro­nicotinate anions and the water mol­ecules of crystallization are assembled into an infinite three-dimensional hydrogen-bonded network via strong O—H⋯O and O—H⋯N hydrogen bonds, leading to the formation of the representative hydrogen-bonded ring motifs: tetra­meric R24(8) and R44(10) loops, a dimeric R22(8) loop and a penta­meric R45(16) loop.

The title complexes, (η4-cyclo­octa-1,5-diene)bis­(1,3-di­methyl­imidazol-2-yl­idene)iridium(I) iodide, [Ir(C5H8N2)2(C8H12)]I, (1) and (η4-cyclo­octa-1,5-di­ene)bis­(1,3-di­ethyl­imidazol-2-yl­idene)iridium(I) iodide, [Ir(C7H12N2)2(C8H12)]I, (2), were prepared using a modified literature method. After carrying out the oxidative addition of the amino acid l-proline to [Ir(COD)(IMe)2]I in water and slowly cooling the reaction to room temperature, a suitable crystal of 1 was obtained and analyzed by single-crystal X-ray diffraction at 100 K. Although this crystal structure has previously been reported in the Pbam space group, it was highly disordered and precise atomic coordinates were not calculated. A single crystal of 2 was also obtained by heating the complex in water and letting it slowly cool to room temperature. Complex 1 was found to crystallize in the monoclinic space group C2/m, while 2 crystallizes in the ortho­rhom­bic space group Pccn, both with Z = 4.

The title centrosymmetric NiII complex, [Ni(NCS)2(C15H22N2O2)2], crystallizes with one half mol­ecule in the asymmetric unit of the monoclinic unit cell. The complex adopts an octa­hedral coordination geometry with two mutually trans benzyl-2-(heptan-4-yl­idene)hydrazine-1-carboxyl­ate ligands in the equatorial plane with the axial positions occupied by N-bound thio­cyanato ligands. The overall conformation of the mol­ecule is also affected by two, inversion-related, intra­molecular C—H⋯O hydrogen bonds. The crystal structure features N—H⋯S, C—H⋯S and C—H⋯N hydrogen bonds together with C—H⋯π contacts that stack the complexes along the b-axis direction. The packing was further explored by Hirshfeld surface analysis. The thermal properties of the complex were also investigated by simultaneous TGA–DTA analyses.

The title compound, C18H16N2O2, consists of perimidine and meth­oxy­phenol units, where the tricyclic perimidine unit contains a naphthalene ring system and a non-planar C4N2 ring adopting an envelope conformation with the NCN group hinged by 47.44 (7)° with respect to the best plane of the other five atoms. In the crystal, O—HPhnl⋯NPrmdn and N—HPrmdn⋯OPhnl (Phnl = phenol and Prmdn = perimidine) hydrogen bonds link the mol­ecules into infinite chains along the b-axis direction. Weak C—H⋯π inter­actions may further stabilize the crystal structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.0%), H⋯C/C⋯H (35.8%) and H⋯O/O⋯H (12.0%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the O—HPhnl⋯NPrmdn and N—HPrmdn⋯OPhnl hydrogen-bond energies are 58.4 and 38.0 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

Terbium oxychloride, TbOCl, was synthesized via the simple heat-treatment of TbCl3·6H2O and its structure was determined by refinement against X-ray powder diffraction data. TbOCl crystallizes with the matlockite (PbFCl) structure in the tetra­gonal space group P4/nmm and is composed of alternating (001) layers of (TbO)n and n Cl−. The unit-cell parameters, unit-cell volume, and density were compared to the literature data of other isostructural rare-earth oxychlorides in the same space group and showed good agreement when compared to the calculated trendlines.

The sexa­dentate ligand 1,1,1-tris­[(salicyl­idene­amino)­meth­yl]ethane has been reported numerous times in its triply deprotonated form coordinated to transition metals and lanthanides, yet it has been rarely employed with main-group elements, including in substituted forms. Its structures with gallium and indium are reported as solvates, namely, ({[(2,2-bis­{[(2-oxido­benzyl­idene)amino-κ2N,O]meth­yl}prop­yl)imino]­meth­yl}phenololato-κ2N,O)gallium(III) pyridine monosolvate, [Ga(C26H24N3O3)]·C5H5N, the aceto­nitrile 0.75-solvate, [Ga(C26H24N3O3)]·0.75C2H3N, and ({[(2,2-bis­{[(2-oxido­benzyl­idene)amino-κ2N,O]meth­yl}prop­yl)imino]­meth­yl}phenololato-κ2N,O)indium(III) di­chloro­methane monosolvate, [In(C26H24N3O3)]·CH2Cl2. All three metal complexes are pseudo-octa­hedral and each structure contains multiple weak C—H⋯O and/or C—H⋯N inter­molecular hydrogen-bonding inter­actions. The syntheses and additional characterization in the forms of melting points, high-resolution mass spectra, infra-red (IR) spectra, and 1H and 13C NMR spectra are also reported.

The asymmetric unit of the title compound, C22H31NO3, comprises of one mol­ecule. The mol­ecule is not planar, with the carboxyl­ate ester group inclined by 33.47 (4)° to the heterocyclic ring. Individual mol­ecules are linked by aromaticC—H⋯Ocarbon­yl hydrogen bonds into chains running parallel to [001]. Slipped π–π stacking inter­actions between quinoline moieties link these chains into layers extending parallel to (100). Hirshfeld surface analysis, two-dimensional fingerprint plots and mol­ecular electrostatic potential surfaces were used to qu­antify the inter­molecular inter­actions present in the crystal, indicating that the most important contributions for the crystal packing are from H⋯H (72%), O⋯H/H⋯O (14.5%) and C⋯H/H⋯C (5.6%) inter­actions.

The title compound, C21H23F2NO, consists of two fluoro­phenyl groups and one butyl group equatorially oriented on a piperidine ring, which adopts a chair conformation. The dihedral angle between the mean planes of the phenyl rings is 72.1 (1)°. In the crystal, N—H⋯O and weak C—H⋯F inter­actions, which form R22[14] motifs, link the mol­ecules into infinite C(6) chains propagating along [001]. A weak C—H⋯π inter­action is also observed. A Hirshfeld surface analysis of the crystal structure indicates that the most significant contributions to the crystal packing are from H⋯H (53.3%), H⋯C/C⋯H (19.1%), H⋯F/F⋯H (15.7%) and H⋯O/O⋯H (7.7%) contacts. Density functional theory geometry-optimized calculations were compared to the experimentally determined structure in the solid state and used to determine the HOMO–LUMO energy gap and compare it to the UV–vis experimental spectrum.

The title compounds, 5-(2H-1,3-benzodioxol-5-yl)-N-cyclo­hexyl­penta-2,4-dienamide, C18H21NO3 (I), and 5-(2H-1,3-benzodioxol-5-yl)-1-(pyrrolidin-1-yl)penta-2,4-dien-1-one C16H17NO3 (II), are derivatives of piperine, which is known as a pungent component of pepper. Their geometrical parameters are similar to those of the three polymorphs of piperine, which indicate conjugation of electrons over the length of the mol­ecules. The extended structure of (I) features N—H⋯O amide hydrogen bonds, which generate C(4) [010] chains. The crystal of (II) features aromatic π–π stacking, as for two of three known piperine polymorphs.

Single crystals of SrFe1.40V0.60O4, strontium tetra­oxidodi[ferrate(III)/vanad­ate(III)], have been obtained as a side product in the course of sinter experiments aimed at the synthesis of double perovskites in the system SrO–Fe2O3–V2O5. The crystal structure can be characterized by layers of six-membered rings of TO4-tetra­hedra (T: FeIII, VIII) perpendicular to [100]. Stacking of the layers along [100] results in a three-dimensional framework enclosing tunnel-like cavities in which SrII cations are incorporated for charge compensation. The sequence of directedness of up (U) and down (D) pointing vertices of neighboring tetra­hedra in a single six-membered ring is UUUDDD. The topology of the tetra­hedral framework belongs to the zeolite-type ABW.

Reaction of 2-(4,4-dimethyl-2-oxazolin-2-yl)aniline (H2-L1) with one equivalent of Na[N(SiMe3)2] in toluene afforded pale-yellow crystals of tetra­meric poly[bis­[μ3-2-(4,4-dimethyl-2-oxazolin-2-yl)anilinido][μ2-2-(4,4-dimethyl-2-oxa­zolin-2-yl)aniline]tetra­sodium(I)], [Na4(C11H13N2O)4]n or [Na4(H-L1)4]n (2), in excellent yield. Subsequent reaction of [Na4(H-L1)4]n (2) with 1.33 equivalents of anhydrous YbCl3 in a 50:50 mixture of toluene–THF afforded yellow crystals of tris­[2-(4,4-dimethyl-2-oxazolin-2-yl)anilinido]ytterbium(III), [Yb(C11H13N2O)3] or Yb(H-L1)3 (3) in moderate yield. Direct reaction of three equivalents of 2-(4',4'-dimethyl-2'-oxazolin­yl)aniline (H2-L1) with Yb[N(SiMe3)2]3 in toluene resulted in elimination of hexa­methyl­disilazane, HN(SiMe3)2, and produced Yb(H-L1)3 (3) in excellent yield. The structure of 2 consists of tetra­meric Na4(H-L1)4 subunits in which each Na+ cation is bound to two H-L1 bridging bidentate ligands and these subunits are connected into a polymeric chain by two of the four oxazoline O atoms bridging to Na+ cations in the adjacent tetra­mer. This results in two 4-coordinate and two 5-coordinate Na+ cations within each tetra­meric unit. The structure of 3 consists of a distorted octa­hedron where the bite angle of ligand L1 ranges between 74.72 (11) and 77.79 (11) degrees. The oxazoline (and anilide) N atoms occupy meridional sites such that for one ligand an anilide nitro­gen is trans to an oxazoline nitro­gen while for the other two oxazoline N atoms are trans to each other. This results in a significantly longer Yb—N(oxazoline) distance [2.468 (3) Å] for the bond trans to the anilide compared to those for the oxazoline N atoms trans to one another [2.376 (3), 2.390 (3) Å].

The structures are described of two bis-chelated metal complexes of nickel(II) and copper(II) with S-n-hexyl 3-(1-phenyl­ethyl­idene)di­thio­carbazate Schiff bases in a cis configuration, namely, bis­[S-n-hexyl 3-(1-phenyl­ethyl­idene)di­thio­carbazato-κ2N3,S]nickel(II), [Ni(C15H21N2S2)2], and bis­[S-n-hexyl 3-(1-phenyl­ethyl­idene)di­thio­carbazato-κ2N3,S]copper(II), [Cu(C15H21N2S2)2]. In both complexes, the metals have distorted square-planar geometries. A search in the Cambridge Structural Database [Groom et al. (2016). Acta Cryst. B72, 171–179] for bis-chelated nickel(II) and copper(II) complexes with similar Schiff bases retrieved 55 and 36 hits for the two metals, respectively. An analysis of the geometrical parameters of complexes showing cis and trans configurations is reported and the values compared with those for the complexes described in this work.

The title compound, C18H16N2O3S, was synthesized by reaction of 2-mercapto-3-phenyl­quinazolin-4(3H)-one with ethyl chloro­acetate. The quinazoline ring forms a dihedral angle of 86.83 (5)° with the phenyl ring. The terminal methyl group is disordered by a rotation of about 60° in a 0.531 (13): 0.469 (13) ratio. In the crystal, C—H⋯O hydrogen-bonding inter­actions result in the formation of columns running in the [010] direction. Two parallel columns further inter­act by C—H⋯O hydrogen bonds. The most important contributions to the surface contacts are from H⋯H (48.4%), C⋯H/H⋯C (21.5%) and O⋯H/H⋯O (18.7%) inter­actions, as concluded from a Hirshfeld analysis.

Five examples each of 3-(5-ar­yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-[4-(prop-2-yn-1-yl­oxy)phen­yl]prop-2-en-1-ones and the corresponding 1-(4-azido­phen­yl)-3-(5-ar­yloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones have been synthesized in a highly efficient manner, starting from a common source precursor, and structures have been determined for three examples of each type. In each of 3-[5-(2-chloro­phen­oxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yl­oxy)phen­yl]prop-2-en-1-one, C28H21ClN2O3, (Ib), the isomeric 3-[5-(2-chloro­phen­oxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yl­oxy)phen­yl]prop-2-en-1-one, (Ic), and 3-[3-methyl-5-(naphthalen-2-yl­oxy)-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn­yloxy)phen­yl]prop-2-en-1-one, C32H24N2O3, (Ie), the mol­ecules are linked into chains of rings, formed by two independent C—H⋯O hydrogen bonds in (Ib) and by a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds in each of (Ic) and (Ie). There are no direction-specific inter­molecular inter­actions in the structure of 1-(4-azido­phen­yl)-3-[3-methyl-5-(2-methyl­phen­oxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C26H21N5O2, (IIa). In 1-(4-azido­phen­yl)-3-[5-(2,4-di­chloro­phen­oxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C25H17Cl2N5O2, (IId), the di­chloro­phenyl group is disordered over two sets of atomic sites having occupancies 0.55 (4) and 0.45 (4), and the mol­ecules are linked by a single C—H⋯O hydrogen bond to form cyclic, centrosymmetric R22(20) dimers. Similar dimers are formed in 1-(4-azido­phen­yl)-3-[3-methyl-5-(naphthalen-2-yl­oxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C29H21N5O2, (IIe), but here the dimers are linked into a chain of rings by two independent C—H..π(arene) hydrogen bonds. Comparisons are made between the mol­ecular conformations within both series of compounds.

The X-ray crystal structure of the title phthalazin-1-one derivative, C17H16N2O3S {systematic name: 2-[(2,4,6-tri­methyl­benzene)­sulfon­yl]-1,2-di­hydro­phthalazin-1-one}, features a tetra­hedral sulfoxide-S atom, connected to phthalazin-1-one and mesityl residues. The dihedral angle [83.26 (4)°] between the organic substituents is consistent with the mol­ecule having the shape of the letter V. In the crystal, phthalazinone-C6-C—H⋯O(sulfoxide) and π(phthalazinone-N2C4)–π(phthalazinone-C6) stacking [inter-centroid distance = 3.5474 (9) Å] contacts lead to a linear supra­molecular tape along the a-axis direction; tapes assemble without directional inter­actions between them. The analysis of the calculated Hirshfeld surfaces confirm the importance of the C—H⋯O and π-stacking inter­actions but, also H⋯H and C—H⋯C contacts. The calculation of the inter­action energies indicate the importance of dispersion terms with the greatest energies calculated for the C—H⋯O and π-stacking inter­actions.

The title compound, C24H30Br2N4O2, consists of a 2-(4-nitro­phen­yl)-4H-imidazo[4,5-b]pyridine entity with a 12-bromo­dodecyl substituent attached to the pyridine N atom. The middle eight-carbon portion of the side chain is planar to within 0.09 (1) Å and makes a dihedral angle of 21.9 (8)° with the mean plane of the imidazolo­pyridine moiety, giving the mol­ecule a V-shape. In the crystal, the imidazolo­pyridine units are associated through slipped π–π stacking inter­actions together with weak C—HPyr⋯ONtr and C—HBrmdc­yl⋯ONtr (Pyr = pyridine, Ntr = nitro and Brmdcyl = bromo­dodec­yl) hydrogen bonds. The 12-bromo­dodecyl chains overlap with each other between the stacks. The terminal –CH2Br group of the side chain shows disorder over two resolved sites in a 0.902 (3):0.098 (3) ratio. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (48.1%), H⋯Br/Br⋯H (15.0%) and H⋯O/O⋯H (12.8%) inter­actions. The optimized mol­ecular structure, using density functional theory at the B3LYP/ 6–311 G(d,p) level, is compared with the experimentally determined structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

N-[(Z)-2-(2H-1,3,2-Benzodioxaborol-2-yl)-2-phenyl­ethen­yl]-N-(propan-2-yl)aniline, C23H22BNO2, contains a C=C bond that is conjugated with a donor and an acceptor group. An analysis that included similar push–pull olefins revealed that bond lengths in their B—C=C—N core units correlate with the perceived acceptor and donor strength of the groups. The two phenyl groups in the mol­ecule are rotated with respect to the plane that contains the BCCN atoms, and are close enough for significant π-stacking. Definite characterization of the title compound demonstrates, for the first time in a reliable way, that hydro­boration of ynamines with borandiol esters is feasible. Compared to olefin hydro­boration with borane, the ynamine substrate is activated enough to undergo reaction with the less active hydro­boration reagent catecholborane.

The title compound, C23H28F3NO, is an ortho-hy­droxy Schiff base compound, which adopts the enol–imine tautomeric form in the solid state. The mol­ecular structure is not planar and the dihedral angle between the planes of the aromatic rings is 85.52 (10)°. The tri­fluoro­methyl group shows rotational disorder over two sites, with occupancies of 0.798 (6) and 0.202 (6). An intra­molecular O—H⋯N hydrogen bonding generates an S(6) ring motif. The crystal structure is consolidated by C—H⋯π inter­actions. The mol­ecular structure was optimized via density functional theory (DFT) methods with the B3LYP functional and LanL2DZ basis set. The theoretical structure is in good agreement with the experimental data. The frontier orbitals and mol­ecular electrostatic potential map were also examined by DFT computations.

In the title compound, C21H15N2+·C7H5O2−, 2-phenyl-1H-phenanthro[9,10-d]imidazole and benzoic acid form an ion pair complex. The system is consolidated by hydrogen bonds along with π–π inter­actions and N—H⋯π inter­actions between the constituent units. For a better understanding of the crystal structure and inter­molecular inter­actions, a Hirshfeld surface analysis was performed.

The title compound, C22H17NO2·C3H7NO, was synthesized by condensation of an aromatic aldehyde with a secondary amine and subsequent reduction. It was crystallized from a di­methyl­formamide solution as a monosolvate, C22H17NO2·C3H7NO. The aromatic mol­ecule is non-planar with a dihedral angle between the mean planes of the aniline moiety and the methyl anthracene moiety of 81.36 (8)°. The torsion angle of the Car­yl—CH2—NH—Car­yl backbone is 175.9 (2)°. The crystal structure exhibits a three-dimensional supra­molecular network, resulting from hydrogen-bonding inter­actions between the carb­oxy­lic OH group and the solvent O atom as well as between the amine functionality and the O atom of the carb­oxy­lic group and additional C—H⋯π inter­actions. Hirshfeld surface analysis was performed to qu­antify the inter­molecular inter­actions.

The crystal structure of MgCO3-II has long been discussed in the literature where DFT-based model calculations predict a pressure-induced transition of the carbon atom from the sp2 to the sp3 type of bonding. We have now determined the crystal structure of iron-bearing MgCO3-II based on single-crystal X-ray diffraction measurements using synchrotron radiation. We laser-heated a synthetic (Mg0.85Fe0.15)CO3 single crystal at 2500 K and 98 GPa and observed the formation of a monoclinic phase with composition (Mg2.53Fe0.47)C3O9 in the space group C2/m that contains tetra­hedrally coordinated carbon, where CO44− tetra­hedra are linked by corner-sharing oxygen atoms to form three-membered C3O96− ring anions. The crystal structure of (Mg0.85Fe0.15)CO3 (magnesium iron carbonate) at 98 GPa and 300 K is reported here as well. In comparison with previous structure-prediction calculations and powder X-ray diffraction data, our structural data provide reliable information from experiments regarding atomic positions, bond lengths, and bond angles.

In the title compound, C25H20O2, the central cyclo­hexenone ring adopts an envelope conformation. The mean plane of the cyclo­hexenone ring makes dihedral angles of 87.66 (11) and 23.76 (12)°, respectively, with the two attached phenyl rings, while it is inclined by 69.55 (11)° to the phenyl ring of the benzoyl group. In the crystal, the mol­ecules are linked by C—H⋯O and C—H⋯π inter­actions, forming a three-dimensional network.

The crystal structures of two salt crystals of 2,2-bis­(4-methyl­phen­yl)hexa­fluoro­propane (Bmphfp) with amines, namely, dipyridinium 4,4'-(1,1,1,3,3,3-hexa­fluoro­propane-2,2-di­yl)dibenzoate 4,4'-(1,1,1,3,3,3-hexa­fluoro­propane-2,2-di­yl)di­benzoic acid, 2C5H6N+·C17H8F6O42−·C17H10F6O4, (1), and a monohydrated ethyl­enedi­ammonium salt ethane-1,2-diaminium 4,4'-(1,1,1,3,3,3-hexa­fluoro­propane-2,2-di­yl)dibenzoate monohydrate, C2H10N22+·C17H8F6O42−·H2O, (2), are reported. Compounds 1 and 2 crystallize, respectively, in space group P21/c with Z' = 2 and in space group Pbca with Z' = 1. The crystals of compound 1 contain neutral and anionic Bmphfp mol­ecules, and form a one-dimensional hydrogen-bonded chain motif. The crystals of compound 2 contain anionic Bmphfp mol­ecules, which form a complex three-dimensional hydrogen-bonded network with the ethyl­enedi­amine and water mol­ecules.

The title compound, [Mn(C3H7NO)4(H2O)2][Cu5(C7H4NO3)4]·C3H7NO or cis-[Mn(H2O)2(DMF)4]{Cu[12-MCCu(II)N(shi)-4]}·DMF, where MC is metallacrown, shi3− is salicyl­hydroximate, and DMF is N,N-di­methyl­formamide, crystallizes in the monoclinic space group P21/n. Two crystallographically independent metallacrown anions are present in the structure, and both anions exhibit minor main mol­ecule disorder by an approximate (non-crystallographic) 180° rotation with occupancy ratios of 0.9010 (9) to 0.0990 (9) for one anion and 0.9497 (8) to 0.0503 (8) for the other. Each penta­copper(II) metallacrown contains four CuII ions in the MC ring and a CuII ion captured in the central cavity. Each CuII ion is four-coordinate with a square-planar geometry. The anionic {Cu[12-MCCu(II)N(shi)-4]}2− is charged-balanced by the presence of a cis-[Mn(H2O)2(DMF)4]2+ cation located in the lattice. In addition, the octa­hedral MnII counter-cation is hydrogen bonded to both MC anions via the coordinated water mol­ecules of the MnII ion. The water mol­ecules form hydrogen bonds with the phenolate and carbonyl oxygen atoms of the shi3− ligands of the MCs.

The title compound, C19H17ClN4O2, was obtained via a two-step synthesis involving the enol-mediated click Dimroth reaction of 4-azido­anisole with methyl 3-cyclo­propyl-3-oxo­propano­ate leading to the 5-cyclo­propyl-1-(4-meth­oxy­phen­yl)-1H-1,2,3-triazole-4-carb­oxy­lic acid and subsequent acid amidation with 4-chloro­aniline by 1,1'-carbonyl­diimidazole (CDI). It crystallizes in space group P21/n, with one mol­ecule in the asymmetric unit. In the extended structure, two mol­ecules arranged in a near coplanar fashion relative to the triazole ring planes are inter­connected by N—H⋯N and C—H⋯N hydrogen bonds into a homodimer. The formation of dimers is a consequence of the above inter­action and the edge-to-face stacking of aromatic rings, which are turned by 58.0 (3)° relative to each other. The dimers are linked by C—H⋯O inter­actions into ribbons. DFT calculations demonstrate that the frontier mol­ecular orbitals are well separated in energy and the HOMO is largely localized on the 4-chloro­phenyl amide motif while the LUMO is associated with aryl­triazole grouping. A Hirshfeld surface analysis was performed to further analyse the inter­molecular inter­actions.

SVAT4 is a computer program for interactive visualization of three-dimensional crystal structures, including chemical bonds and magnetic moments. A wide range of functions, e.g. revealing atomic layers and polyhedral clusters, are available for further structural analysis. Atomic sizes, colors, appearance, view directions and view modes (orthographic or perspective views) are adjustable. Customized work for the visualization and analysis can be saved and then reloaded. SVAT4 provides a template to simplify the process of preparation of a new data file. SVAT4 can generate high-quality images for publication and animations for presentations. The usability of SVAT4 is broadened by a software suite for simulation and analysis of electron diffraction patterns.

Ni-based intermetallics are promising materials for forming efficient contacts in GeSn-based Si photonic devices. However, the role that Sn might have during the Ni/GeSn solid-state reaction (SSR) is not fully understood. A comprehensive analysis focused on Sn segregation during the Ni/GeSn SSR was carried out. In situ X-ray diffraction and cross-section transmission electron microscopy measurements coupled with energy-dispersive X-ray spectrometry and electron energy-loss spectroscopy atomic mappings were performed to follow the phase sequence, Sn distribution and segregation. The results showed that, during the SSR, Sn was incorporated into the intermetallic phases. Sn segregation happened first around the grain boundaries (GBs) and then towards the surface. Sn accumulation around GBs hampered atom diffusion, delaying the growth of the Ni(GeSn) phase. Higher thermal budgets will thus be mandatory for formation of contacts in high-Sn-content photonic devices, which could be detrimental for thermal stability.

The fact that a protein crystal can serve as a chemical reaction vessel is intrinsically fascinating. That it can produce an electron-dense tetranuclear rhenium cluster compound from a rhenium tri­carbonyl tri­bromo starting compound adds to the fascination. Such a cluster has been synthesized previously in vitro, where it formed under basic conditions. Therefore, its synthesis in a protein crystal grown at pH 4.5 is even more unexpected. The X-ray crystal structures presented here are for the protein hen egg-white lysozyme incubated with a rhenium tri­carbonyl tri­bromo compound for periods of one and two years. These reveal a completed, very well resolved, tetra-rhenium cluster after two years and an intermediate state, where the carbonyl ligands to the rhenium cluster are not yet clearly resolved, after one year. A dense tetranuclear rhenium cluster, and its technetium form, offer enhanced contrast in medical imaging. Stimulated by these crystallography results, the unusual formation of such a species directly in an in vivo situation has been considered. It offers a new option for medical imaging compounds, particularly when considering the application of the pre-formed tetranuclear cluster, suggesting that it may be suitable for medical diagnosis because of its stability, preference of formation and biological compatibility.

In this work, two methods of high-resolution X-ray data refinement: multipole refinement (MM) and Hirshfeld atom refinement (HAR) – together with X-ray wavefunction refinement (XWR) – are applied to investigate the refinement of positions and anisotropic thermal motion of hydrogen atoms, experiment-based reconstruction of electron density, refinement of anharmonic thermal vibrations, as well as the effects of excluding the weakest reflections in the refinement. The study is based on X-ray data sets of varying quality collected for the crystals of four quinoline derivatives with Cl, Br, I atoms and the -S-Ph group as substituents. Energetic investigations are performed, comprising the calculation of the energy of intermolecular interactions, cohesive and geometrical relaxation energy. The results obtained for experimentally derived structures are verified against the values calculated for structures optimized using dispersion-corrected periodic density functional theory. For the high-quality data sets (the Cl and -S-Ph compounds), both MM and XWR could be successfully used to refine the atomic displacement parameters and the positions of hydrogen atoms; however, the bond lengths obtained with XWR were more precise and closer to the theoretical values. In the application to the more challenging data sets (the Br and I compounds), only XWR enabled free refinement of hydrogen atom geometrical parameters, nevertheless, the results clearly showed poor data quality. For both refinement methods, the energy values (intermolecular interactions, cohesive and relaxation) calculated for the experimental structures were in similar agreement with the values associated with the optimized structures – the most significant divergences were observed when experimental geometries were biased by poor data quality. XWR was found to be more robust in avoiding incorrect distortions of the reconstructed electron density as a result of data quality issues. Based on the problem of anharmonic thermal motion refinement, this study reveals that for the most correct interpretation of the obtained results, it is necessary to use the complete data set, including the weak reflections in order to draw conclusions.