It is pointed out that many authors are unaware that the particular choice of unit-cell origin determines the irreducible representations to which octahedral tilts in perovskites belong. Furthermore, a recommendation is made that the preferred option is with the origin at the B-cation site rather than that of the A site.

A polycrystalline sample LuCrO3 has been characterized by neutron powder diffraction (NPD) and magnetization measurements. Its crystal structure has been Rietveld refined from NPD data in space group Pnma; this perovskite contains strongly tilted CrO6 octahedra with extremely bent Cr—O—Cr superexchange angles of ∼142°. The NPD data show that below Néel temperature (TN ≃ 131 K), the magnetic structure can be defined as an A-type antiferromagnetic arrangement of Cr3+ magnetic moments, aligned along the b axis, with a canting along the c axis. A noticeable magneto­strictive effect is observed in the unit-cell parameters and volume upon cooling down across TN. The AC magnetic susceptibility indicates the onset of magnetic ordering below 112.6 K; the magnetization isotherms below TN show a nonlinear behaviour that is associated with the described canting of the Cr3+ magnetic moments. From the Curie–Weiss law, the effective moment of the Cr3+ sublattice is found to be μeff = 3.55 μB (calculated 3.7 μB) while the ΘCW parameter yields a value of −155 K, indicating antiferromagnetic interactions. There is a conspicuous increase of TN upon the application of external pressure, which must be due to shortening of the Cr—O bond length under compression that increases the orbital overlap integral.

Magnetic materials featuring triangular arrangements of spins are frequently investigated as platforms hosting magnetic frustration. Hexagonal perovskites with ordered vacancies serve as excellent candidates for two-dimensional triangular magnetism due to the considerable separation of the magnetic planes. In this work, the effects of chemical pressure on the ferromagnetic ground state of Ba2La2NiW2O12 by substitution of Ba2+ with Sr2+ to produce Sr2La2NiW2O12 are investigated. The two materials are characterized using synchrotron-based XRD, XANES and EXAFS in addition to magnetometry in order to correlate their crystal structures and magnetic properties. Both materials form in space group R3, yet as a result of the enhanced bending of key bond angles due to the effects of chemical pressure, the TC value of the magnetic Ni2+ sublattice is reduced from ∼6 K in Ba2La2NiW2O12 to 4 K in Sr2La2NiW2O12.

Synthesis experiments were conducted in the quaternary system K2O–Na2O–CaO–SiO2, resulting in the formation of a previously unknown compound with the composition K0.72Na1.71Ca5.79Si6O19. Single crystals of sufficient size and quality were recovered from a starting mixture with a K2O:Na2O:CaO:SiO2 molar ratio of 1.5:0.5:2:3. The mixture was confined in a closed platinum tube and slowly cooled from 1150°C at a rate of 0.1°C min−1 to 700°C before being finally quenched in air. The structure has tetragonal symmetry and belongs to space group P4122 (No. 91), with a = 7.3659 (2), c = 32.2318 (18) Å, V = 1748.78 (12) Å3, and Z = 4. The silicate anion consists of highly puckered, unbranched six-membered oligomers with the composition [Si6O19] and point group symmetry 2 (C2). Although several thousands of natural and synthetic oxosilicates have been structurally characterized, this compound is the first representative of a catena-hexasilicate anion, to the best of our knowledge. Structural investigations were completed using Raman spectroscopy. The spectroscopic data was interpreted and the bands were assigned to certain vibrational species with the support of density functional theory at the HSEsol level of theory. To determine the stability properties of the novel oligosilicate compared to those of the chemically and structurally similar cyclo­silicate combeite, we calculated the electronegativity of the respective structures using the electronegativity equalization method. The results showed that the molecular electronegativity of the cyclo­silicate was significantly higher than that of the oligostructure due to the different connectivities of the oxygen atoms within the molecular units.

In recent decades, sustained theoretical and software developments have clearly established that representation analysis and magnetic symmetry groups are complementary concepts that should be used together in the investigation and description of magnetic structures. Historically, they were considered alternative approaches, but currently, magnetic space groups and magnetic superspace groups can be routinely used together with representation analysis, aided by state-of-the-art software tools. After exploring the historical antagonism between these two approaches, we emphasize the significant advancements made in understanding and formally describing magnetic structures by embracing their combined use.

Organic–inorganic hybrid crystals have diverse functionalities, for example in energy storage and luminescence, due to their versatile structures. The synthesis and structural characterization of a new cobalt–vanadium-containing compound, 2[Co(en)3]3+(V4O13)6−·4H2O (1) is presented. The crystal structure of 1, consisting of [Co(en)3]3+ complexes and chains of corner-sharing (VO4) tetrahedra, was solved by single-crystal X-ray diffraction in the centrosymmetric space group P1. Phase purity of the bulk material was confirmed by infrared spectroscopy, scanning electron microscopy, elemental analysis and powder X-ray diffraction. The volume expansion of 1 was found to be close to 1% in the reported temperature range from 100 to 300 K, with a volume thermal expansion coefficient of 56 (2) × 10−6 K−1. The electronic band gap of 1 is 2.30 (1) eV, and magnetic susceptibility measurements showed that the compound exhibits a weak paramagnetic response down to 1.8 K, probably due to minor CoII impurities (<1%) on the CoIII site.

The magnetic and crystal structures of manganese and nickel monoxides have been studied using high-resolution neutron diffraction. The known 1k-structures based on the single propagation vector [½ ½ ½] for the parent paramagnetic space group Fm3m are forced to have monoclinic magnetic symmetry and are not possible in rhombohedral symmetry. However, the monoclinic distortions from the rhombohedral crystal metric allowed by symmetry are very small, and the explicit monoclinic splittings of the diffraction peaks have not been experimentally observed. We analyse the magnetic crystallographic models metrically compatible with our experimental data in full detail by using isotropy subgroup representation approach, including rhombohedral solutions based on the propagation vector star {[½ ½ ½], [−½ ½ ½], [½−½ ½], [½ ½ −½]}. Although the full star rhombohedral RI3c structure can equally well fit our diffraction data for NiO, we conclude that the best solution for the crystal and magnetic structures for NiO and MnO is the 1k monoclinic model with the magnetic space group Cc2/c (Belov–Neronova–Smirnova No. 15.90, UNI symbol C2/c.1'c[C2/m]).

Thio­phosgene is one of the principal C=S building blocks in synthetic chemistry. At room temperature, thio­phosgene is a red liquid. While its properties in the liquid and gaseous states are well known, a comprehensive characterization of thio­phosgene in its solid state is presented here. Differential scanning calorimetry shows that thio­phosgene forms a supercooled melt before rapidly crystallizing. Its melting point is 231.85 K (−41.3 °C). At 80 K, thio­phosgene crystallizes in space group P63/m [No. 174, a = b = 5.9645 (2), c = 6.2835 (3) Å, V = 193.59 (2) Å3]. The molecule shows a distinct rotational disorder: all S and Cl positions are of mixed occupancy and the disorder does not resolve at temperatures as low as 10 K, as was shown by neutron powder diffraction. Infrared, Raman and inelastic neutron scattering spectra were collected and assigned with the aid of quantum chemical calculations. A larger ordered structural model allowed for better agreement between the measured and calculated spectra, further indicating that disorder is an inherent feature of solid-state thio­phosgene.

JANA2020 is a program developed for the solution and refinement of regular, twinned, modulated, and composite crystal structures. In addition, JANA2020 also includes a magnetic option for solving magnetic structures from powder and single-crystal neutron diffraction data. This tool uses magnetic space and superspace symmetry to describe commensurate and incommensurate magnetic structures. The basics of the underlying formulation of magnetic structure factors and the use of magnetic symmetry for handling modulated and non-modulated magnetic structures are presented here, together with the general features of the magnetic tool. Examples of structures solved in the magnetic option of JANA2020 are given to illustrate the operation and capabilities of the program.

An exhaustive search for missing symmetry was performed for 223 076 entries in the ICSD (2023-2 release). Approximately 0.65% of them can be described with higher symmetry than reported. Out of the identified noncentrosymmetric entries, ∼74% can be described by centrosymmetric space groups; this has implications for compatible physical properties. It is proposed that the information on the correct space group is included in the ICSD.

The embedded call to a special version of the web-based Bilbao Crystallographic Server tool k-SUBGROUPSMAG from within GSAS-II to form a list of all possible commensurate magnetic subgroups of a parent magnetic grey group is described. It facilitates the selection and refinement of the best commensurate magnetic structure model by having all the analysis tools including Rietveld refinement in one place as part of GSAS-II. It also provides the chosen magnetic space group as one of the 1421 possible standard Belov–Neronova–Smirnova forms or equivalent non-standard versions.

Onchocerca volvulus causes blindness, onchocerciasis, skin infections and devastating neurological diseases such as nodding syndrome. New treatments are needed because the currently used drug, ivermectin, is contraindicated in pregnant women and those co-infected with Loa loa. The Seattle Structural Genomics Center for Infectious Disease (SSGCID) produced, crystallized and determined the apo structure of N-terminally hexahistidine-tagged O. volvulus macrophage migration inhibitory factor-1 (His-OvMIF-1). OvMIF-1 is a possible drug target. His-OvMIF-1 has a unique jellyfish-like structure with a prototypical macrophage migration inhibitory factor (MIF) trimer as the `head' and a unique C-terminal `tail'. Deleting the N-terminal tag reveals an OvMIF-1 structure with a larger cavity than that observed in human MIF that can be targeted for drug repurposing and discovery. Removal of the tag will be necessary to determine the actual biological oligomer of OvMIF-1 because size-exclusion chomatographic analysis of His-OvMIF-1 suggests a monomer, while PISA analysis suggests a hexamer stabilized by the unique C-terminal tails.

The nitro­gen–sulfur Schiff base proligand S-n-octyl 3-(1-phenyl­ethyl­idene)di­thio­carbazate, C17H26N2S2 (HL), was prepared by reaction of S-octyl di­thio­carbamate with aceto­phenone. Treatment of HL with nickel acetate yielded the complex bis­[S-n-octyl 3-(1-phenyl­ethyl­idene)di­thio­carbazato]nickel(II), [Ni(C17H25N2S2)2] (NiL2), which was shown to adopt a tetra­hedrally distorted cis-square-planar coordination geometry, with the NiSN planes of the two ligands forming a dihedral angle of 21.66 (6)°. Changes in the geometry of the L ligand upon chelation of Ni2+ are described, involving a ca 180° rotation around the N(azomethine)—C(thiol­ate) bond.

The compounds bis­(morpholine-κN)gold(I) chloride, [Au(C4H9NO)2]Cl, 1, and bis­(morpholine-κN)gold(I) bromide, [Au(C4H9NO)2]Br, 2, crystallize isotypically in space group C2/c with Z = 4. The gold atoms, which are axially positioned at the morpholine rings, lie on inversion centres (so that the N—Au—N coordination is exactly linear) and the halide anions on twofold axes. The residues are connected by a classical hydrogen bond N—H⋯halide and by a short gold⋯halide contact to form a layer structure parallel to the bc plane. The morpholine oxygen atom is not involved in classical hydrogen bonding.

The title compound, C5H5NO2, is a hy­droxy­lated pyridine ring that has been studied for its involvement in microbial degradation of nicotinic acid. Here we describe its synthesis as a formic acid salt, rather than the standard hydro­chloride salt that is commercially available, and its spectroscopic and crystallographic characterization.

The reaction of cadmium bromide tetra­hydrate with 3-amino­pyrazole (3-apz) in ethano­lic solution leads to tautomerization of the ligand and the formation of crystals of the title compound, catena-poly[[di­bromido­cadmium(II)]-bis­(μ-3-amino-1H-pyrazole)-κ2N3:N2;κ2N2:N3], [CdBr2(C3H5N3)2]n or [CdBr2(3-apz)2]n. Its asymmetric unit consists of a half of a Cd2+ cation, a bromide anion and a 3-apz mol­ecule. The Cd2+ cations are coordinated by two bromide anions and two 3-apz ligands, generating trans-CdN4Br2 octa­hedra, which are linked into chains by pairs of the bridging ligands. In the crystal, the ligand mol­ecules and bromide anions of neighboring chains are linked through inter­chain hydrogen bonds into a two-dimensional network. The inter­molecular contacts were qu­anti­fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative qu­anti­tative contributions of the weak inter­molecular contacts.

Single crystals of tricadmium orthophosphate, Cd3(PO4)2, have been synthesized successfully by the hydro­thermal route, while its powder form was obtained by a solid-solid process. The corresponding crystal structure was determined using X-ray diffraction data in the monoclinic space group P21/n. The crystal structure consists of Cd2O8 or Cd2O10 dimers linked together by PO4 tetra­hedra through sharing vertices or edges. Scanning electron microscopy (SEM) was used to investigate the morphology and to confirm the chemical composition of the synthesized powder. Infrared analysis corroborates the presence of isolated phosphate tetra­hedrons in the structure. UV–Visible studies showed an absorbance peak at 289 nm and a band gap energy of 3.85 eV, as determined by the Kubelka–Munk model.

In the title compound, C15H14N2O2·H2O, the 1H-pyrrole ring makes a dihedral angle of 59.95 (13)° with the phenyl ring. In the crystal, the mol­ecules are connected by C—H⋯O hydrogen bonds into layers parallel to the (020) plane, while two mol­ecules are connected to the water mol­ecule by two N—H⋯O hydrogen bonds and one mol­ecule by an O—H⋯O hydrogen bond. C—H⋯π and π–π inter­actions further link the mol­ecules into chains extending in the [overline{1}01] direction and stabilize the mol­ecular packing. According to a Hirshfeld surface study, H⋯H (49.4%), C⋯H/H⋯C (23.2%) and O⋯H/H⋯O (20.0%) inter­actions are the most significant contributors to the crystal packing.

We report the synthesis and structures of two transition-metal complexes involving 2-(2-hy­droxy­phen­yl)benzimidazole (2hpbi – a ligand of inter­est for its photoluminescent applications), with cobalt, namely, bis­[μ-2-(1H-1,3-benzo­diazol-2-yl)phenolato]bis­[ethanol(thio­cyanato)­cobalt(II)], [Co2(C13H9N2O)2(NCS)2(C2H6O)2], (1), and manganese, namely, bis­[μ-2-(1H-1,3-benzo­diazol-2-yl)phenolato]bis­{[2-(1H-1,3-benzo­diazol-2-yl)phenolato](thio­cyanato)­mang­an­ese(III)} dihydrate, [Mn2(C13H9N2O)4(NCS)2]·2H2O, (2). These structures are two recent examples of a fruitful collaboration between researchers at the Laboratoire de Chimie de Coordination Organique/Organic Coordination Chemistry Laboratory (LCCO), University of Dakar, Senegal and the National Crystallography Service (NCS), School of Chemistry, University Southampton, UK. This productive partnership was forged through meeting at Pan-African Conferences on Crystallography and quickly grew as the plans for the AfCA (African Crystallographic Association) developed. This article therefore also showcases this productive partnership, in celebration of the IUCr's 75 year anniversary and the recent inclusion of AfCA as a Regional Associate of the IUCr.

Reaction of FeCl2·4H2O with KSCN and 3-cyano­pyridine (pyridine-3-carbo­nitrile) in ethanol accidentally leads to the formation of single crystals of Fe(NCS)(Cl)(3-cyano­pyridine)4 or [FeCl(NCS)(C6H4N2)4]. The asymmetric unit of this compound consists of one FeII cation, one chloride and one thio­cyanate anion that are located on a fourfold rotation axis as well as of one 3-cyano­pyridine coligand in a general position. The FeII cations are sixfold coordinated by one chloride anion and one terminally N-bonding thio­cyanate anion in trans-positions and four 3-cyano­pyridine coligands that coordinate via the pyridine N atom to the FeII cations. The complexes are arranged in columns with the chloride anions, with the thio­cyanate anions always oriented in the same direction, which shows the non-centrosymmetry of this structure. No pronounced inter­molecular inter­actions are observed between the complexes. Initially, FeCl2 and KSCN were reacted in a 1:2 ratio, which lead to a sample that contains the title compound as the major phase together with a small amount of an unknown crystalline phase, as proven by powder X-ray diffraction (PXRD). If FeCl2 and KSCN is reacted in a 1:1 ratio, the title compound is obtained as a nearly pure phase. IR investigations reveal that the CN stretching vibration for the thio­cyanate anion is observed at 2074 cm−1, and that of the cyano group at 2238 cm−1, which also proves that the anionic ligands are only terminally bonded and that the cyano group is not involved in the metal coordination. Measurements with thermogravimetry and differential thermoanalysis reveal that the title compound decomposes at 169°C when heated at a rate of 4°C min−1 and that the 3-cyano­pyridine ligands are emitted in two separate poorly resolved steps. After the first step, an inter­mediate compound with the composition Fe(NCS)(Cl)(3-cyano­pyridine)2 of unknown structure is formed, for which the CN stretching vibration of the thio­cyanate anion is observed at 2025 cm−1, whereas the CN stretching vibration of the cyano group remain constant. This strongly indicates that the FeII cations are linked by μ-1,3-bridg­ing thio­cyanate anions into chains or layers.

The title mol­ecule, C29H44N8O, adopts a conformation resembling a two-bladed fan with the octyl chains largely in fully extended conformations. In the crystal, C—H⋯O hydrogen bonds form chains of mol­ecules extending along the b-axis direction, which are linked by weak C—H⋯N hydrogen bonds and C—H⋯π inter­actions to generate a three-dimensional network. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (68.3%), H⋯N/N⋯H (15.7%) and H⋯C/C⋯H (10.4%) inter­actions.

The reaction between the (R,S)-fixolide 4-methyl­thio­semicarbazone and PdII chloride yielded the title compound, [Pd(C20H30N3S)2]·C2H6O {common name: trans-bis­[(R,S)-fixolide 4-methyl­thio­semicarbazonato-κ2N2S]palladium(II) ethanol monosolvate}. The asymmetric unit of the title compound consists of one bis-thio­semicarbazonato PdII complex and one ethanol solvent mol­ecule. The thio­semicarbazononato ligands act as metal chelators with a trans configuration in a distorted square-planar geometry. A C—H⋯S intra­molecular inter­action, with graph-set motif S(6), is observed and the coordination sphere resembles a hydrogen-bonded macrocyclic environment. Additionally, one C—H⋯Pd anagostic inter­action can be suggested. Each ligand is disordered over the aliphatic ring, which adopts a half-chair conformation, and two methyl groups [s.o.f. = 0.624 (2):0.376 (2)]. The disorder includes the chiral carbon atoms and, remarkably, one ligand has the (R)-isomer with the highest s.o.f. value atoms, while the other one shows the opposite, the atoms with the highest s.o.f. value are associated with the (S)-isomer. The N—N—C(=S)—N fragments of the ligands are approximately planar, with the maximum deviations from the mean plane through the selected atoms being 0.0567 (1) and −0.0307 (8) Å (r.m.s.d. = 0.0403 and 0.0269 Å) and the dihedral angle with the respective aromatic rings amount to 46.68 (5) and 50.66 (4)°. In the crystal, the complexes are linked via pairs of N—H⋯S inter­actions, with graph-set motif R22(8), into centrosymmetric dimers. The dimers are further connected by centrosymmetric pairs of ethanol mol­ecules, building mono-periodic hydrogen-bonded ribbons along [011]. The Hirshfeld surface analysis indicates that the major contributions for the crystal cohesion are [atoms with highest/lowest s.o.f.s considered separately]: H⋯H (81.6/82.0%), H⋯C/C⋯H (6.5/6.4%), H⋯N/N⋯H (5.2/5.0%) and H⋯S/S⋯H (5.0/4.9%).

In the title mol­ecule, C7H7N3O, the pyrimidine ring is essentially planar, with the propynyl group rotated out of this plane by 15.31 (4)°. In the crystal, a tri-periodic network is formed by N—H⋯O, N—H⋯N and C—H⋯O hydrogen-bonding and slipped π–π stacking inter­actions, leading to narrow channels extending parallel to the c axis. Hirshfeld surface analysis of the crystal structure reveals that the most important contributions for the crystal packing are from H⋯H (36.2%), H⋯C/C⋯H (20.9%), H⋯O/O⋯H (17.8%) and H⋯N/N⋯H (12.2%) inter­actions, showing that hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicates that the stabilization is dominated by the electrostatic energy contributions. The mol­ecular structure optimized by density functional theory (DFT) calculations 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 also elucidated to determine the energy gap.

The ternary magnesium/lithium boride, MgxLi3 − xB48 − y (x = 1.11, y = 0.40, idealized formula MgLi2B48), crystallizes as its own structure type in P43212, which is closely related to the structural family comprising α-AlB12, Be0.7Al1.1B22 and tetra­gonal β-boron. The asymmetric unit of title structure contains two statistical mixtures Mg/Li in Wyckoff sites 8b with relative occupancies Mg:Li = 0.495 (9):0.505 (9) and 4a with Mg:Li = 0.097 (8):0.903 (8). The boron atoms occupy 23 8b sites and two 4a sites. One of the latter sites has a partial occupancy factor of 0.61 (2). Both unique Mg/Li atoms adopt a twelvefold coordination environment in the form of truncated tetra­hedra (Laves polyhedra). These polyhedra are connected by triangular faces to four [B12] icosa­hedra. The boron atoms exhibit four kinds of polyhedra, namely penta­gonal pyramid (coordination number CN = 6), distorted tetra­gonal pyramid (CN = 5), bicapped hexa­gon (CN = 8) and gyrobifastigium (CN = 8). At the gas hydrogenation of MgLi2B48 alloy, formation of the eutectic composite hydride LiBH4+Mg(BH4)2 and amorphous boron is observed. In the temperature range 543–623 K, the hydride eutectics decompose, forming MgH2, LiH, MgB4, B and H2.

The tetra­kis complex of neodymium(III), tetra­kis­{μ-N-[bis­(pyrrolidin-1-yl)phos­phor­yl]acet­am­id­ato}bis(pro­pan-2-ol)neodymiumsodium pro­pan-2-ol monosol­vate, [NaNd(C10H16Cl3N3O2)4(C3H8O)2]·C3H8O or NaNdPyr4(i-PrOH)2·i-PrOH, with the amide type CAPh ligand bis(N,N-tetra­methylene)(tri­chloro­acetyl)phos­phoric acid tri­amide (HPyr), has been synthesized, crystallized and characterized by X-ray diffraction. The complex does not have the tetra­kis­(CAPh)lanthanide anion, which is typical for ester-type CAPh-based coordin­ation compounds. Instead, the NdO8 polyhedron is formed by one oxygen atom of a 2-propanol mol­ecule and seven oxygen atoms of CAPh ligands in the title compound. Three CAPh ligands are coordinated in a bidentate chelating manner to the NdIII ion and simultaneously binding the sodium cation by μ2-bridging PO and CO groups while the fourth CAPh ligand is coordinated to the sodium cation in a bidentate chelating manner and, due to the μ2-bridging function of the PO group, also binds the neodymium ion.

The mol­ecular and crystal structure of a discrete [Ni8(μ4-OH)6(μ-4-Rpz)12]2− (R = H; pz = pyrazolate anion, C3H3N2−) cluster with an unprecedented, perfectly cubic arrangement of its eight Ni centers is reported, along with its lower-symmetry alkyl-functionalized (R = methyl and n-oct­yl) derivatives. Crystals of the latter two were obtained with two identical counter-ions (Bu4N+), whereas the crystal of the complex with the parent pyrazole ligand has one Me4N+ and one Bu4N+ counter-ion. The methyl derivative incorporates 1,2-di­chloro­ethane solvent mol­ecules in its crystal structure, whereas the other two are solvent-free. The compounds are tetra­butyl­aza­nium tetra­methyl­aza­nium hexa-μ4-hydroxido-dodeca-μ2-pyrazolato-hexa­hedro-octa­nickel, (C16H36N)(C4H12N)[Ni8(C3H3N2)12(OH)6] or (Bu4N)(Me4N)[Ni8(μ4-OH)6(μ-pz)12] (1), bis­(tetra­butyl­aza­nium) hexa-μ4-hydroxido-dodeca-μ2-(4-methyl­pyrazolato)-hexa­hedro-octa­nickel 1,2-di­chloro­ethane 7.196-solvate, (C16H36N)2[Ni8(C4H5N2)12(OH)6]·7.196C2H4Cl2 or (Bu4N)2[Ni8(μ4-OH)6(μ-4-Mepz)12]·7.196(ClCH2CH2Cl) (2), and bis­(tetra­butyl­aza­nium) hexa-μ4-hydroxido-dodeca-μ2-(4-octylpyrazolato)-hexa­hedro-octa­nickel, (C16H36N)2[Ni8(C11H19N2)12(OH)6] or (Bu4N)2[Ni8(μ4-OH)6(μ-4-nOctpz)12] (3). All counter-ions are disordered (with the exception of one Bu4N+ in 3). Some of the octyl chains of 3 (the crystal is twinned by non-merohedry) are also disordered. Various structural features are discussed and contrasted with those of other known [Ni8(μ4-OH)6(μ-4-Rpz)12]2− complexes, including extended three-dimensional metal–organic frameworks. In all three structures, the Ni8 units are lined up in columns.

The title compound, C15H15F3N2O3S, crystallizes in the monoclinic system, space group I2/a, with Z = 8. As expected, the nine-membered heterobicyclic system is virtually planar and the cyclo­hexyl group adopts a chair conformation. There is structural evidence for intra­molecular N—S⋯O chalcogen bonding between the benziso­thia­zolinone S atom and one O atom of the nitro group, approximately aligned along the extension of the covalent N—S bond [N—S⋯O = 162.7 (1)°]. In the crystal, the mol­ecules form centrosymmetric dimers through C—H⋯O weak hydrogen bonding between a C—H group of the electron-deficient benzene ring and the benzo­thia­zolinone carbonyl O atom with an R22(10) motif. In contrast to the previously described N-acyl 7-nitro-5-(tri­fluoro­meth­yl)benzo[d]iso­thia­zol-3(2H)-ones, the title N-cyclo­hexyl­methyl analogue does not inhibit growth of Mycobacterium aurum and Mycobacterium smegmatis in vitro.

A novel o-phenyl­enedi­amine (opda)-based cadmium complex, bis­(benzene-1,2-di­amine-κ2N,N')bis­(benzene-1,2-di­amine-κN)cadmium(II) naphthalene-1,5-di­sulfonate, [Cd(C6H8N2)4](C10H6O6S2), was synthesized. The complex salt crystallizes in the monoclinic space group C2/c. The Cd atom occupies a special position and coordinates six nitro­gen atoms from four o-phenyl­enedi­amine mol­ecules, two as chelating ligands and two as monodentate ligands. The amino H atoms of opda inter­act with two O atoms of the naphthalene-1,5-di­sulfonate anions. The anions act as bridges between [Cd(opda)4]2+ cations, forming a two-dimensional network in the [010] and [001] directions. The Hirshfeld surface analysis shows that the primary factors contributing to the supramolecular inter­actions are short contacts, particularly van der Waals forces of the type H⋯H, O⋯H and C⋯H.

Single crystals of NbF5, niobium(V) fluoride, have been obtained by the reaction of niobium metal in a stream of dilute elemental fluorine at 473 K and subsequent sublimation. The as-obtained bulk phase compound was shown to be pure by powder X-ray diffraction at 293 K and by IR and Raman spectroscopy. A single-crystal X-ray analysis was conducted at 100 K. In comparison to the previously reported structure model [Edwards (1964). J. Chem. Soc. pp. 3714–3718], the lattice parameters and fractional atom coordinates were determined to much higher precision and individual, anisotropic displacement parameters were refined for all atoms.

In the title compound, C19H20Cl2N2O, the seven-membered 1,4-diazepane ring adopts a chair conformation while the 4-chloro­phenyl substituents adopt equatorial orientations. The chloro­phenyl ring at position 7 is disordered over two positions [site occupancies 0.480 (16):0.520 (16)]. The dihedral angle between the two benzene rings is 63.0 (4)°. The methyl groups at position 3 have an axial and an equatorial orientation. The compound exists as a dimer exhibiting inter­molecular N—H⋯O hydrogen bonding with R22(8) graph-set motifs. The crystal structure is further stabilized by C—H⋯O hydrogen bonds together with two C—Cl⋯π (ring) inter­actions. The geometry was optimized by DFT using the B3LYP/6–31 G(d,p) level basis set. In addition, the HOMO and LUMO energies, chemical reactivity parameters and mol­ecular electrostatic potential were calculated at the same level of theory. Hirshfeld surface analysis indicated that the most important contributions to the crystal packing are from H⋯H (45.6%), Cl⋯H/H⋯Cl (23.8%), H⋯C/C⋯H (12.6%), H⋯O/O⋯H (8.7%) and C⋯Cl/Cl⋯C (7.1%) inter­actions. Analysis of the inter­action energies showed that the dispersion energy is greater than the electrostatic energy. A crystal void volume of 237.16 Å3 is observed. A mol­ecular docking study with the human oestrogen receptor 3ERT protein revealed good docking with a score of −8.9 kcal mol−1.

Two new copper dimers, namely, bis­(dimethyl sulfoxide)­tetra­kis­(μ-pyrene-1-carboxyl­ato)dicopper(Cu—Cu), [Cu2(C17H9O2)4(C2H6OS)2] or [Cu2(pyr-COO−)4(DMSO)2] (1), and bis­(di­methyl­formamide)­tetra­kis­(μ-pyrene-1-carboxyl­ato)dicopper(Cu—Cu), [Cu2(C17H9O2)4(C3H7NO)2] or [Cu2(pyr-COO−)4(DMF)2] (2) (pyr = pyrene), were synthesized from the reaction of pyrene-1-carb­oxy­lic acid, copper(II) nitrate and tri­ethyl­amine from solvents DMSO and DMF, respectively. While 1 crystallized in the space group Poverline{1}, the crystal structure of 2 is in space group P21/n. The Cu atoms have octa­hedral geometries, with four oxygen atoms from carboxyl­ate pyrene ligands occupying the equatorial positions, a solvent mol­ecule coordinating at one of the axial positions, and a Cu⋯Cu contact in the opposite position. The packing in the crystal structures exhibits π–π stacking inter­actions and short contacts through the solvent mol­ecules. The Hirshfeld surfaces and two-dimensional fingerprint plots were generated for both compounds to better understand the inter­molecular inter­actions and the contribution of heteroatoms from the solvent ligands to the crystal packing. In addition, a Cu2+/Cu1+ quasi-reversible redox process was identified for compound 2 using cyclic voltammetry that accounts for a diffusion-controlled electron-donation process to the Cu dimer.

The title compound, C20H16N2O2, is composed of two monosubstituted benzene rings and one benzimidazole unit. The benzimidazole moiety subtends dihedral angles of 46.16 (7) and 77.45 (8)° with the benzene rings, which themselves form a dihedral angle of 54.34 (9)°. The crystal structure features O—H⋯N and O—H⋯O hydrogen-bonding inter­actions, which together lead to the formation of two-dimensional hydrogen-bonded layers parallel to the (101) plane. In addition, π–π inter­actions also contribute to the crystal cohesion. Hirshfeld surface analysis indicates that the most significant contacts in the crystal packing are: H⋯H (47.5%), O⋯H/H⋯O (12.4%), N⋯H/H⋯N (6.1%), C⋯H/H⋯C (27.6%) and C⋯C (4.6%).

The title compound, [RuCl2(C33H43N3O)], is an example of a new generation of N,N-dialkyl ruthenium catalysts with an N—Ru coordination bond as part of a six-membered chelate ring. The Ru atom has an Addison τ parameter of 0.244, which indicates a geometry inter­mediate between square-based pyramidal and trigonal–bipyramidal. The complex shows the usual trans arrangement of the two chlorides, with Ru—Cl bond lengths of 2.3515 (8) and 2.379 (7) Å, and a Cl—Ru—Cl angle of 158.02 (3)°. One of the chlorine atoms and the atoms of the 2-meth­oxy-N-methyl-N-[(2-methyl­phen­yl)meth­yl]ethane-1-amine group of the title complex display disorder over two positions in a 0.889 (2): 0.111 (2) ratio.

The title complex, [ZnCl(C12H15N3O2)2][ZnCl3(CH3CN)], was synthesized and its structure was fully characterized through single-crystal X-ray diffraction analysis. The complex crystallizes in the ortho­rhom­bic system, space group Pbca (61), with a central zinc atom coordinating one chlorine atom and two pyrrolidinyl-4-meth­oxy­phenyl azoformamide ligands in a bidentate manner, utilizing both the nitro­gen and oxygen atoms in a 1,3-heterodiene (N=N—C=O) motif for coordinative bonding, yielding an overall positively (+1) charged complex. The complex is accompanied by a [(CH3CN)ZnCl3]− counter-ion. The crystal data show that the harder oxygen atoms in the heterodiene zinc chelate form bonding inter­actions with distances of 2.002 (3) and 2.012 (3) Å, while nitro­gen atoms are coordinated by the central zinc cation with bond lengths of 2.207 (3) and 2.211 (3) Å. To gain further insight into the inter­molecular inter­actions within the crystal, Hirshfeld surface analysis was performed, along with the calculation of two-dimensional fingerprint plots. This analysis revealed that H⋯H (39.9%), Cl⋯H/H⋯Cl (28.2%) and C⋯H/H⋯C (7.2%) inter­actions are dominant. This unique crystal structure sheds light on arrangement and bonding inter­actions with azo­formamide ligands, and their unique qualities over similar semicarbazone and azo­thio­formamide structures.

The asymmetric unit of the title compound, μ-biphenyl-4,4'-di­sulfonato-bis­(aqua­lithium), [Li2(C12H8O6S2)(H2O)2] or Li2[Bph(SO3)2](H2O)2, consists of an Li ion, half of the diphenyl-4,4'-di­sulfonate [Bph(SO3−)2] ligand, and a water mol­ecule. The Li ion exhibits a four-coordinate tetra­hedral geometry with three oxygen atoms of the Bph(SO3−)2 ligands and a water mol­ecule. The tetra­hedral LiO4 units, which are inter­connected by biphenyl moieties, form a layer structure parallel to (100). These layers are further connected by hydrogen-bonding inter­actions to yield a three-dimensional network.

The structures of 16 phosphane chalcogenide complexes of gold(I) halides, with the general formula R13-nR2nPEAuX (R1 = t-butyl; R2 = isopropyl; n = 0 to 3; E = S or Se; X = Cl, Br or I), are presented. The eight possible chlorido derivatives are: 1a, n = 3, E = S; 2a, n = 2, E = S; 3a, n = 1, E = S; 4a, n = 0, E = S; 5a, n = 3, E = Se; 6a, n = 2, E = Se; 7a, n = 1, E = Se; and 8a, n = 0, E = Se, and the corresponding bromido derivatives are 1b–8b in the same order. However, 2a and 2b were badly disordered and 8a was not obtained. The iodido derivatives are 2c, 6c and 7c (numbered as for the series a and b). All structures are solvent-free and all have Z' = 1 except for 6b and 6c (Z' = 2). All mol­ecules show the expected linear geometry at gold and approximately tetra­hedral angles P—E—Au. The presence of bulky ligands forces some short intra­molecular contacts, in particular H⋯Au and H⋯E. The Au—E bond lengths have a slight but consistent tendency to be longer when trans to a softer X ligand, and vice versa. The five compounds 1a, 5a, 6a, 1b and 5b form an isotypic set, despite the different alkyl groups in 6a. Compounds 3a/3b, 4b/8b and 6b/6c form isotypic pairs. The crystal packing can be analysed in terms of various types of secondary inter­actions, of which the most frequent are `weak' hydrogen bonds from methine hydrogen atoms to the halogenido ligands. For the structure type 1a, H⋯X and H⋯E contacts combine to form a layer structure. For 3a/3b, the packing is almost featureless, but can be described in terms of a double-layer structure involving borderline H⋯Cl/Br and H⋯S contacts. In 4a and 4b/8b, which lack methine groups, Cmeth­yl—H⋯X contacts combine to form layer structures. In 7a/7b, short C—H⋯X inter­actions form chains of mol­ecules that are further linked by association of short Au⋯Se contacts to form a layer structure. The packing of compound 6b/6c can conveniently be analysed for each independent mol­ecule separately, because they occupy different regions of the cell. Mol­ecule 1 forms chains in which the mol­ecules are linked by a Cmethine⋯Au contact. The mol­ecules 2 associate via a short Se⋯Se contact and a short H⋯X contact to form a layer structure. The packing of compound 2c can be described in terms of two short Cmethine—H⋯I contacts, which combine to form a corrugated ribbon structure. Compound 7c is the only compound in this paper to feature Au⋯Au contacts, which lead to twofold-symmetric dimers. Apart from this, the packing is almost featureless, consisting of layers with only translation symmetry except for two very borderline Au⋯H contacts.

The synthetic availability of mol­ecular water oxidation catalysts containing high-valent ions of 3d metals in the active site is a prerequisite to enabling photo- and electrochemical water splitting on a large scale. Herein, the synthesis and crystal structure of di­ammonium {μ-1,3,4,7,8,10,12,13,16,17,19,22-dodeca­aza­tetra­cyclo­[8.8.4.13,17.18,12]tetra­cosane-5,6,14,15,20,21-hexa­onato}ferrate(IV) acetic acid tris­olvate, (NH4)2[FeIV(C12H12N12O6)]·3CH3COOH or (NH4)2[FeIV(L–6H)]·3CH3COOH is reported. The FeIV ion is encapsulated by the macropolycyclic ligand, which can be described as a dodeca-aza-quadricyclic cage with two capping tri­aza­cyclo­hexane fragments making three five- and six six-membered alternating chelate rings with the central FeIV ion. The local coord­ination environment of FeIV is formed by six deprotonated hydrazide nitro­gen atoms, which stabilize the unusual oxidation state. The FeIV ion lies on a twofold rotation axis (multiplicity 4, Wyckoff letter e) of the space group C2/c. Its coordination geometry is inter­mediate between a trigonal prism (distortion angle φ = 0°) and an anti­prism (φ = 60°) with φ = 31.1°. The Fe—N bond lengths lie in the range 1.9376 (13)–1.9617 (13) Å, as expected for tetra­valent iron. Structure analysis revealed that three acetic acid mol­ecules additionally co-crystallize per one iron(IV) complex, and one of them is positionally disordered over four positions. In the crystal structure, the ammonium cations, complex dianions and acetic acid mol­ecules are inter­connected by an intricate system of hydrogen bonds, mainly via the oxamide oxygen atoms acting as acceptors.

In the structure of the title compound, C19H19N3O5S·C4H8O2, the two independent dioxane mol­ecules each display inversion symmetry. The pyrazole ring is approximately parallel to the aromatic ring of the oxy-ethanone group and approximately perpendicular to the tolyl ring of the sulfonyl substituent. An extensive system of classical and `weak' hydrogen bonds connects the residues to form a layer structure parallel to (201), within which dimeric subunits are conspicuous; neighbouring layers are connected by classical hydrogen bonds to dioxanes and by `weak' hydrogen bonds from Htol­yl donors.

This paper summarizes brief perspectives on the historic process of establishing an African Crystallographic Association (AfCA) and includes representative references. It covers activities within four arbitrarily selected, approximate time slots, i.e., 1890s–1999, 2000–2013, 2014–2019 and 2020–2023. A genuine attempt is made to include appropriate role players, organizations and accompanying events within these periods. It concludes with the official admission of AfCA as the fifth Regional Associate of the IUCr at the 26th Congress and General Assembly of the IUCr in Melbourne, Australia in 2023.

The title compound, [Cu(HL)2(H2O)2] or [Cu(C4H4N3O2)2(H2O)2], is a mononuclear octa­hedral CuII complex based on 5-methyl-1H-1,2,4-triazole-3-carb­oxy­lic acid (H2L). [Cu(HL)2(H2O)2] was synthesized by reaction of H2L with copper(II) nitrate hexa­hydrate (2:1 stoichiometric ratio) in water under ambient conditions to produce clear light-blue crystals. The central Cu atom exhibits an N2O4 coordination environment in an elongated octa­hedral geometry provided by two bidentate HL− anions in the equatorial plane and two water mol­ecules in the axial positions. Hirshfeld surface analysis revealed that the most important contributions to the surface contacts are from H⋯O/O⋯H (33.1%), H⋯H (29.5%) and H⋯N/N⋯H (19.3%) inter­actions.

The title compound, [Co(NCS)2(C6H7NO)]n or Co(NCS)2(2-methyl­pyridine N-oxide), was prepared by the reaction of Co(NCS)2 and 2-methyl­pyridine N-oxide in methanol. All crystals obtained by this procedure show reticular pseudo-merohedric twinning, but after recrystallization, one crystal was found that had a minor component with only a very few overlapping reflections. The asymmetric unit consists of one CoII cation, two thio­cyanate anions and one 2-methyl­pyridine N-oxide coligand in general positions. The CoII cations are octa­hedrally coordinated by two O-bonding 2-methyl­pyridine N-oxide ligands, as well as two S- and two N-bonding thio­cyanate anions, and are connected via μ-1,3(N,S)-bridging thio­cyanate anions into chains that are linked by μ-1,1(O,O) bridging coligands into layers. No pronounced directional inter­molecular inter­actions are observed between the layers. The 2-methyl­pyridine coligand is disordered over two orientations and was refined using a split model with restraints. Powder X-ray diffraction (PXRD) indicates that a pure sample was obtained and IR spectroscopy confirms that bridging thio­cyanate anions are present. Thermogravimetry and differential thermoanalysis (TG-DTA) shows one poorly resolved mass loss in the TG curve that is accompanied by an exothermic and an endothermic signal in the DTA curve, which indicate the decomposition of the 2-methyl­pyridine N-oxide coligands.

In the title compound, C25H25NO7S, the mol­ecular conformation is stabilized by intra­molecular O—H⋯O and N—H⋯O hydrogen bonds, which form S(6) and S(8) ring motifs, respectively. The mol­ecules are bent at the S atom with a C—SO2—NH—C torsion angle of −70.86 (11)°. In the crystal, mol­ecules are linked by C—H⋯O and N—H⋯O hydrogen bonds, forming mol­ecular layers parallel to the (100) plane. C—H⋯π inter­actions are observed between these layers.

In the title compound, C20H18N2S, the asymmetric unit comprises two similar mol­ecules (A and B). In mol­ecule A, the central thio­phene ring makes dihedral angles of 89.96 (12) and 57.39 (13)° with the 1H-pyrrole rings, which are bent at 83.22 (14)° relative to each other, and makes an angle of 85.98 (11)° with the phenyl ring. In mol­ecule B, the corresponding dihedral angles are 89.49 (13), 54.64 (12)°, 83.62 (14)° and 85.67 (11)°, respectively. In the crystal, mol­ecular pairs are bonded to each other by N—H⋯N inter­actions. N—H⋯π and C—H⋯π inter­actions further connect the mol­ecules, forming a three-dimensional network. A Hirshfeld surface analysis indicates that H⋯H (57.1% for mol­ecule A; 57.3% for mol­ecule B), C⋯H/H⋯C (30.7% for mol­ecules A and B) and S⋯H/H⋯S (6.2% for mol­ecule A; 6.4% for mol­ecule B) inter­actions are the most important contributors to the crystal packing.

In the title compound, C18H22O7, two hexane rings and an oxane ring are fused together. The two hexane rings tend toward a distorted boat conformation, while the tetra­hydro­furan and di­hydro­furan rings adopt envelope conformations. The oxane ring is puckered. The crystal structure features C—H⋯O hydrogen bonds, which link the mol­ecules into a three-dimensional network. According to a Hirshfeld surface study, H⋯H (60.3%) and O⋯H/H⋯O (35.3%) inter­actions are the most significant contributors to the crystal packing.

At room temperature, the title salt, C7H10NO+·Cl−, is ortho­rhom­bic, space group Pbca with Z' = 1, as previously reported [Zhao (2009). Acta Cryst. E65, o2378]. Between 250 and 200 K, there is a solid-state phase transition to a twinned monoclinic P21/c structure with Z' = 2. We report the high temperature structure at 250 K and the low-temperature structure at 100 K. In the low-temperature structure, the –NH3 hydrogen atoms are ordered and this group has a different orientation in each independent mol­ecule, in keeping with optimizing N—H⋯Cl hydrogen bonding, some of which are bifurcated: these hydrogen bonds have N⋯Cl distances in the range 3.1201 (8)–3.4047 (8) Å. In the single cation of the high-temperature structure, the NH hydrogen atoms are disordered into the average of the two low-temperature positions and the N⋯Cl hydrogen bond distances are in the range 3.1570 (15)–3.3323 (18) Å. At both temperatures, the meth­oxy group is nearly coplanar with the rest of the mol­ecule, with the C—C—O—C torsion angles being −7.0 (2)° at 250 K and −6.94 (12) and −9.35 (12)° at 100 K. In the extended ortho­rhom­bic structure, (001) hydrogen-bonded sheets occur; in the monoclinic structure, the sheets propagate in the (010) plane.

Syntheses of the acyclic amidinium salts, morpholino­formamidinium hexa­fluorido­phosphate [OC4H8N—CH=NH2]PF6 or C5H11N2O+·PF6−, 1, and pyrrolidinoformamidinium hexa­fluorido­phosphate [C4H8N—CH= NH2]PF6 or C5H11N2+·PF6−, 2, were carried out by heating either morpholine or pyrrolidine with triethyl orthoformate and ammonium hexa­fluorido­phosphate. Crystals of 1 obtained directly from the reaction mixture contain one cation and one anion in the asymmetric unit. The structure involves cations linked in chains parallel to the b axis by N—H⋯O hydrogen bonds in space group Pbca, with glide-related chains pointing in opposite directions. Crystals of 1 obtained by recrystallization from ethanol, however, showed a similar unit cell and the same basic structure, but unexpectedly, there was positional disorder [occupancy ratio 0.639 (4):0.361 (4)] in one of the cation chains, which lowered the crystal symmetry to the non-centrosymmetric space group Pca21, with two cations and anions in the asymmetric unit. In the pyrrolidino compound, 2, cations and anions are ordered and are stacked separately, with zigzag N—H⋯F hydrogen-bonding between stacks, forming ribbons parallel to (101), extended along the b-axis direction. Slight differences in the delocalized C=N distances between the two cations may reflect the inductive effect of the oxygen atom in the morpholino compound.

In the title compound, (2-methyl­idene-1,2-di­hydro­pyridinium-κN)tris­(tetra­hydro­furan-κO)lithium, [Li(C6H6N)(C4H8O)3], the lithium ion adopts a distorted LiNO3 tetra­hedral coordination geometry and the 2-picolyl anion adopts its enamido form with the lithium ion lying close to the plane of the pyridine ring. A methyl­ene group of one of the thf ligands is disordered over two orientations. In the crystal, a weak C—H⋯O inter­action generates inversion dimers. A Hirshfeld surface analysis shows that H⋯H contacts dominate the packing (86%) followed by O⋯H/H⋯O and C⋯H/H⋯C contacts, which contribute 3% and 10.4%, respectively.

JUAMI, the joint undertaking for an African materials institute, is a project to build collaborations and materials research capabilities between PhD researchers in Africa, the United States, and the world. Focusing on research-active universities in the East African countries of Kenya, Ethiopia, Tanzania and Uganda, the effort has run a series of schools focused on materials for sustainable energy and materials for sustainable development. These bring together early-career researchers from Africa, the US, and beyond, for two weeks in a close-knit environment. The program includes lectures on cutting-edge research from internationally renowned speakers, highly interactive tutorial lectures on the science behind the research, also from internationally known researchers, and hands-on practicals and team-building exercises that culminate in group proposals from self-formed student teams. The schools have benefited more than 300 early-career students and led to proposals that have received funding and have led to research collaborations and educational non-profits. JUAMI continues and has an ongoing community of alumni who share resources and expertise, and is open to like-minded people who want to join and develop contacts and collaborations internationally.

The reaction of the Schiff base 2-[1-(pyridin-2-yl)ethyl­idene­amino]­ethanol (HL), which is formed by reaction of 2-amino­ethanol and 2-acetyl­pyridine with CuBr2 in ethanol results in the isolation of the new polymeric complex poly[hexa-μ-bromido-bis­{2-[1-(pyridin-2-yl)ethyl­idene­amino]­ethano­lato}tetra­copper(II)], [Cu4Br6(C9H11N2O)2]n or [Cu4Br6L2]n. The asymmetric unit of the crystal structure of the polymeric [Cu4Br6L2]n complex is composed by four copper (II) cations, two monodeprotonated mol­ecules of the ligand, and six bromide anions, which act as bridges. The ligand mol­ecules act in a tridentate fashion through their azomethine nitro­gen atoms, their pyridine nitro­gen atoms, and their alcoholate O atoms. The crystal structure shows two types of geometries in the coordination polyhedrons around Cu2+ ions. Two copper cations are situated in a square-based pyramidal environment, while the two other copper cations adopt a tetra­hedral geometry. Bromides anions acting as bridges between two metal ions connect the units, resulting in a tetra­nuclear polymer compound.