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Characterizing electron-collecting CdTe for use in a 77 ns burst-rate imager

The Keck-PAD (pixel array detector) was developed at Cornell as a burst-rate imager capable of recording images from successive electron bunches (153 ns period) from the Advanced Photon Source (APS). Both Si and hole-collecting Schottky CdTe have been successfully bonded to this ASIC (application-specific integrated circuit) and used with this frame rate. The facility upgrades at the APS will lower the bunch period to 77 ns, which will require modifications to the Keck-PAD electronics to image properly at this reduced period. In addition, operation at high X-ray energies will require a different sensor material having a shorter charge collection time. For the target energy of 40 keV for this project, simulations have shown that electron-collecting CdTe should allow >90% charge collection within 35 ns. This collection time will be sufficient to sample the signal from one frame and prepare for the next. 750 µm-thick electron-collecting Schottky CdTe has been obtained from Acrorad and bonded to two different charge-integrating ASICs developed at Cornell, the Keck-PAD and the CU-APS-PAD. Carrier mobility has been investigated using the detector response to single X-ray bunches at the Cornell High Energy Synchrotron Source and to a pulsed optical laser. The tests indicate that the collection time will meet the requirements for 77 ns imaging.




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Correcting angular distortions in Bragg coherent X-ray diffraction imaging

Bragg coherent X-ray diffraction imaging (BCDI) has emerged as a powerful technique for strain imaging and morphology reconstruction of nanometre-scale crystals. However, BCDI often suffers from angular distortions that appear during data acquisition, caused by radiation pressure, heating or imperfect scanning stages. This limits the applicability of BCDI, in particular for small crystals and high-flux X-ray beams. Here, we present a pre-processing algorithm that recovers the 3D datasets from the BCDI dataset measured under the impact of large angular distortions. We systematically investigate the performance of this method for different levels of distortion and find that the algorithm recovers the correct angles for distortions up to 16.4× (1640%) the angular step size dθ = 0.004°. We also show that the angles in a continuous scan can be recovered with high accuracy. As expected, the correction provides marked improvements in the subsequent phase retrieval.




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Prediction of the treatment effect of FLASH radiotherapy with synchrotron radiation from the Circular Electron–Positron Collider (CEPC)

The Circular Electron–Positron Collider (CEPC) in China can also work as an excellent powerful synchrotron light source, which can generate high-quality synchrotron radiation. This synchrotron radiation has potential advantages in the medical field as it has a broad spectrum, with energies ranging from visible light to X-rays used in conventional radiotherapy, up to several megaelectronvolts. FLASH radiotherapy is one of the most advanced radiotherapy modalities. It is a radiotherapy method that uses ultra-high dose rate irradiation to achieve the treatment dose in an instant; the ultra-high dose rate used is generally greater than 40 Gy s−1, and this type of radiotherapy can protect normal tissues well. In this paper, the treatment effect of CEPC synchrotron radiation for FLASH radiotherapy was evaluated by simulation. First, a Geant4 simulation was used to build a synchrotron radiation radiotherapy beamline station, and then the dose rate that the CEPC can produce was calculated. A physicochemical model of radiotherapy response kinetics was then established, and a large number of radiotherapy experimental data were comprehensively used to fit and determine the functional relationship between the treatment effect, dose rate and dose. Finally, the macroscopic treatment effect of FLASH radiotherapy was predicted using CEPC synchrotron radiation through the dose rate and the above-mentioned functional relationship. The results show that the synchrotron radiation beam from the CEPC is one of the best beams for FLASH radiotherapy.




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A distributed software system for integrating data-intensive imaging methods in a hard X-ray nanoprobe beamline at the SSRF

The development of hard X-ray nanoprobe techniques has given rise to a number of experimental methods, like nano-XAS, nano-XRD, nano-XRF, ptychography and tomography. Each method has its own unique data processing algorithms. With the increase in data acquisition rate, the large amount of generated data is now a big challenge to these algorithms. In this work, an intuitive, user-friendly software system is introduced to integrate and manage these algorithms; by taking advantage of the loosely coupled, component-based design approach of the system, the data processing speed of the imaging algorithm is enhanced through optimization of the parallelism efficiency. This study provides meaningful solutions to tackle complexity challenges faced in synchrotron data processing.




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Electrochemical cell for synchrotron nuclear resonance techniques

Developing new materials for Li-ion and Na-ion batteries is a high priority in materials science. Such development always includes performance tests and scientific research. Synchrotron radiation techniques provide unique abilities to study batteries. Electrochemical cell design should be optimized for synchrotron studies without losing electrochemical performance. Such design should also be compatible with operando measurement, which is the most appropriate approach to study batteries and provides the most reliable results. The more experimental setups a cell can be adjusted for, the easier and faster the experiments are to carry out and the more reliable the results will be. This requires optimization of window materials and sizes, cell topology, pressure distribution on electrodes etc. to reach a higher efficiency of measurement without losing stability and reproducibility in electrochemical cycling. Here, we present a cell design optimized for nuclear resonance techniques, tested using nuclear forward scattering, synchrotron Mössbauer source and nuclear inelastic scattering.




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Accelerating imaging research at large-scale scientific facilities through scientific computing

To date, computed tomography experiments, carried-out at synchrotron radiation facilities worldwide, pose a tremendous challenge in terms of the breadth and complexity of the experimental datasets produced. Furthermore, near real-time three-dimensional reconstruction capabilities are becoming a crucial requirement in order to perform high-quality and result-informed synchrotron imaging experiments, where a large amount of data is collected and processed within a short time window. To address these challenges, we have developed and deployed a synchrotron computed tomography framework designed to automatically process online the experimental data from the synchrotron imaging beamlines, while leveraging the high-performance computing cluster capabilities to accelerate the real-time feedback to the users on their experimental results. We have, further, integrated it within a modern unified national authentication and data management framework, which we have developed and deployed, spanning the entire data lifecycle of a large-scale scientific facility. In this study, the overall architecture, functional modules and workflow design of our synchrotron computed tomography framework are presented in detail. Moreover, the successful integration of the imaging beamlines at the Shanghai Synchrotron Radiation Facility into our scientific computing framework is also detailed, which, ultimately, resulted in accelerating and fully automating their entire data processing pipelines. In fact, when compared with the original three-dimensional tomography reconstruction approaches, the implementation of our synchrotron computed tomography framework led to an acceleration in the experimental data processing capabilities, while maintaining a high level of integration with all the beamline processing software and systems.




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Comparing single-shot damage thresholds of boron carbide and silicon at the European XFEL

Xray free-electron lasers (XFELs) enable experiments that would have been impractical or impossible at conventional X-ray laser facilities. Indeed, more XFEL facilities are being built and planned, with their aim to deliver larger pulse energies and higher peak brilliance. While seeking to increase the pulse power, it is quintessential to consider the maximum pulse fluence that a grazing-incidence FEL mirror can withstand. To address this issue, several studies were conducted on grazing-incidence damage by soft X-ray FEL pulses at the European XFEL facility. Boron carbide (B4C) coatings on polished silicon substrate were investigated using 1 keV photon energy, similar to the X-ray mirrors currently installed at the soft X-ray beamlines (SASE3). The purpose of this study is to compare the damage threshold of B4C and Si to determine the advantages, tolerance and limits of using B4C coatings.




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Indirect detector for ultra-high-speed X-ray micro-imaging with increased sensitivity to near-ultraviolet scintillator emission

Ultra-high-speed synchrotron-based hard X-ray (i.e. above 10 keV) imaging is gaining a growing interest in a number of scientific domains for tracking non-repeatable dynamic phenomena at spatio-temporal microscales. This work describes an optimized indirect X-ray imaging microscope designed to achieve high performance at micrometre pixel size and megahertz acquisition speed. The entire detector optical arrangement has an improved sensitivity within the near-ultraviolet (NUV) part of the emitted spectrum (i.e. 310–430 nm wavelength). When combined with a single-crystal fast-decay scintillator, such as LYSO:Ce (Lu2−xYxSiO5:Ce), it exploits the potential of the NUV light-emitting scintillators. The indirect arrangement of the detector makes it suitable for high-dose applications that require high-energy illumination. This allows for synchrotron single-bunch hard X-ray imaging to be performed with improved true spatial resolution, as herein exemplified through pulsed wire explosion and superheated near-nozzle gasoline injection experiments at a pixel size of 3.2 µm, acquisition rates up to 1.4 MHz and effective exposure time down to 60 ps.




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A new dual-thickness semi-transparent beamstop for small-angle X-ray scattering

An innovative dual-thickness semi-transparent beamstop designed to enhance the performance of small-angle X-ray scattering (SAXS) experiments is introduced. This design integrates two absorbers of differing thicknesses side by side into a single attenuator, known as a beamstop. Instead of completely stopping the direct beam, it attenuates it, allowing the SAXS detector to measure the transmitted beam through the sample. This approach achieves true synchronization in measuring both scattered and transmitted signals and effectively eliminates higher-order harmonic contributions when determining the transmission light intensity through the sample. This facilitates and optimizes signal detection and background subtraction. This contribution details the theoretical basis and practical implementation of this solution at the SAXS station on the 1W2A beamline at the Beijing Synchrotron Radiation Facility. It also anticipates its application at other SAXS stations, including that at the forthcoming High Energy Photon Source, providing an effective solution for high-precision SAXS experiments.




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Methyl 1-(4-fluoro­benz­yl)-1H-indazole-3-carboxyl­ate

The title compound, C16H13FN2O2, was synthesized by nucleophilic substitution of the indazole N—H hydrogen atom of methyl 1H-indazole-3-carboxyl­ate with 1-(bromo­meth­yl)-4-fluoro­benzene. In the crystal, some hydrogen-bond-like inter­actions are observed.




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A second crystalline modification of 2-{3-methyl-2-[(2Z)-pent-2-en-1-yl]cyclo­pent-2-en-1-yl­idene}hydrazinecarbo­thio­amide

A second crystalline modification of the title compound, C12H19N3S [common name: cis-jasmone thio­semicarbazone] was crystallized from tetra­hydro­furane at room temperature. There is one crystallographic independent mol­ecule in the asymmetric unit, showing disorder in the cis-jasmone chain [site-occupancy ratio = 0.590 (14):0.410 (14)]. The thio­semicarbazone entity is approximately planar, with the maximum deviation from the mean plane through the N/N/C/S/N atoms being 0.0463 (14) Å [r.m.s.d. = 0.0324 Å], while for the five-membered ring of the jasmone fragment, the maximum deviation from the mean plane through the carbon atoms amounts to 0.0465 (15) Å [r.m.s.d. = 0.0338 Å]. The mol­ecule is not planar due to the dihedral angle between these two fragments, which is 8.93 (1)°, and due to the sp3-hybridized carbon atoms in the jasmone fragment chain. In the crystal, the mol­ecules are connected by N—H⋯S and C—H⋯S inter­actions, with graph-set motifs R22(8) and R21(7), building mono-periodic hydrogen-bonded ribbons along [010]. A Hirshfeld surface analysis indicates that the major contributions for the crystal cohesion are H⋯H (67.8%), H⋯S/S⋯H (15.0%), H⋯C/C⋯H (8.5%) and H⋯N/N⋯H (5.6%) [only non-disordered atoms and those with the highest s.o.f. were considered]. This work reports the second crystalline modification of the cis-jasmone thio­semicarbazone structure, the first one being published recently [Orsoni et al. (2020). Int. J. Mol. Sci. 21, 8681–8697] with the crystals obtained in ethanol at 273 K.




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2-{1-[(6R,S)-3,5,5,6,8,8-Hexamethyl-5,6,7,8-tetra­hydro­naphthalen-2-yl]ethyl­idene}-N-methyl­hydrazinecarbo­thioamide

The reaction between a racemic mixture of (R,S)-fixolide and 4-methyl­thio­semicarbazide in ethanol with a 1:1 stoichiometric ratio and catalysed with HCl, yielded the title compound, C20H31N3S [common name: (R,S)-fixolide 4-methyl­thio­semicarbazone]. There is one crystallographically independent mol­ecule in the asymmetric unit, which is disordered over the aliphatic ring [site-occupancy ratio = 0.667 (13):0.333 (13)]. The disorder includes the chiral C atom, the neighbouring methyl­ene group and the methyl H atoms of the methyl group bonded to the chiral C atom. The maximum deviations from the mean plane through the disordered aliphatic ring amount to 0.328 (6) and −0.334 (6) Å [r.m.s.d. = 0.2061 Å], and −0.3677 (12) and 0.3380 (12) Å [r.m.s.d. = 0.2198 Å] for the two different sites. Both fragments show a half-chair conformation. Additionally, the N—N—C(=S)—N entity is approximately planar, with the maximum deviation from the mean plane through the selected atoms being 0.0135 (18) Å [r.m.s.d. = 0.0100 Å]. The mol­ecule is not planar due to the dihedral angle between the thio­semicarbazone entity and the aromatic ring, which amounts to 51.8 (1)°, and due to the sp3-hybridized carbon atoms of the fixolide fragment. In the crystal, the mol­ecules are connected by H⋯S inter­actions with graph-set motif C(4), forming a mono-periodic hydrogen-bonded ribbon along [100]. The Hirshfeld surface analysis suggests that the major contributions for the crystal cohesion are [(R,S)-isomers considered separately] H⋯H (75.7%), H⋯S/S⋯H (11.6%), H⋯C/C⋯H (8.3% and H⋯N/N⋯H (4.4% for both of them).




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2-{3-Methyl-2-[(2Z)-pent-2-en-1-yl]cyclo­pent-2-en-1-yl­idene}-N-phenylhydrazinecarbo­thio­amide. Corrigendum

In the paper by Oliveira et al. [IUCrData (2023), 8, x230971], there was an error in the name of the first author.




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N-Methyl-2-{3-methyl-2-[(2Z)-pent-2-en-1-yl]cyclo­pent-2-en-1-yl­idene}hydrazinecarbo­thio­amide

The equimolar and hydro­chloric acid-catalysed reaction between cis-jasmone and 4-methyl­thio­semicarbazide in ethano­lic solution yields the title compound, C13H21N3S (common name: cis-jasmone 4-methyl­thio­semicarbazone). Two mol­ecules with all atoms in general positions are present in the asymmetric unit. In one of them, the carbon chain is disordered [site occupancy ratio = 0.821 (3):0.179 (3)]. The thio­semicarbazone entities [N—N—C(=S)—N] are approximately planar, with the maximum deviation from the mean plane through the selected atoms being −0.0115 (16) Å (r.m.s.d. = 0.0078 Å) for the non-disordered mol­ecule and 0.0052 (14) Å (r.m.s.d. = 0.0031 Å) for the disordered one. The mol­ecules are not planar, since the jasmone groups have a chain with sp3-hybridized carbon atoms and, in addition, the thio­semicarbazone fragments are attached to the respective carbon five-membered rings and the dihedral angles between them for each mol­ecule amount to 8.9 (1) and 6.3 (1)°. In the crystal, the mol­ecules are connected through pairs of N—H⋯S and C—H⋯S inter­actions into crystallographically independent centrosymmetric dimers, in which rings of graph-set motifs R22(8) and R21(7) are observed. A Hirshfeld surface analysis indicates that the major contributions for the crystal cohesion are from H⋯H (70.6%), H⋯S/S⋯H (16.7%), H⋯C/C⋯H (7.5%) and H⋯N/N⋯H (4.9%) inter­actions [considering the two crystallographically independent mol­ecules and only the disordered atoms with the highest s.o.f. for the evaluation].




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Bis[S-octyl 3-(2-methyl­propyl­idene)di­thio­carb­az­ato-κ2N3,S]nickel(II)

The central NiII atom in the title complex, [Ni(C13H25N2S2)2], is located on an inversion center and adopts a roughly square-planar coordination environment defined by two chelating N,S donor sets of two symmetry-related ligands in a trans configuration. The Ni—N and Ni—S bond lenghts are 1.9193 (14) and 2.1788 (5) Å, respectively, with a chelating N—Ni—S bond angle of 86.05 (4)°. These data are compared with those measured for similar di­thio­carbazato ligands that bear n-octyl or n-hexyl alkyl chains. Slight differences are observed with respect to the phenyl­ethyl­idene derivative where the ligands are bound cis relative to one another.




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Methyl N-{(1R)-2-[(meth­oxy­carbon­yl)­oxy]-1-phenyleth­yl}carbamate

The title mol­ecule, C12H15NO5, is a methyl carbamate derivative obtained by reacting (R)-2-phenyl­glycinol and methyl chloro­formate, with calcium hydroxide as heterogeneous catalyst. Supra­molecular chains are formed in the [100] direction, based on N—H⋯O hydrogen bonds between the amide and carboxyl­ate groups. These chains weakly inter­act in the crystal, and the phenyl rings do not display significant π–π inter­actions.




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4-Fluoro­benzyl (Z)-2-(2-oxoindolin-3-yl­idene)hydrazine-1-carbodi­thio­ate

The title compound, C16H12FN3OS, a fluorinated di­thio­carbazate imine derivative, was synthesized by the one-pot, multi-component condensation reaction of hydrazine hydrate, carbon di­sulfide, 4-fluoro­benzyl chloride and isatin. The compound demonstrates near-planarity across much of the mol­ecule in the solid state and a Z configuration for the azomethine C=N bond. The Z form is further stabilized by the presence of an intra­molecular N—H⋯O hydrogen bond. In the extended structure, mol­ecules are linked into dimers by N—H⋯O hydrogen bonds and further connected into chains along either [2overline{1}0] or [100] by weak C—H⋯S and C—H⋯F hydrogen bonds, which further link into corrugated sheets and in combination form the overall three-dimensional network.




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mer-Bis(quinoline-2-carboxaldehyde 4-ethyl­thio­semicarbazonato)nickel(II) methanol 0.33-solvate 0.67-hydrate

In the title compound, [Ni(C13H13N4S)2]·0.33CH3OH·0.67H2O, the NiII atom is coordinated by two tridentate quinoline-2-carboxaldehyde 4-ethyl­thio­semi­car­ba­zonate ligands in a distorted octa­hedral shape. At 100 K, the crystal symmetry is monoclinic (space group P21/n). A mixture of water and methanol crystallizes with the title complex, and one of the ethyl groups in the coordinating ligands is disordered over two positions, with an occupancy ratio of 58:42. There is inter­molecular hydrogen bonding between the solvent mol­ecules and the amine and thiol­ate groups in the ligands. No other significant inter­actions are present in the crystal packing.




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(S)-2-Carb­oxy­ethyl l-cysteinyl sulfone

The title compound {systematic name: (2S)-2-aza­niumyl-3-[(2-carb­oxy­ethane)­sulfon­yl]propano­ate}, C6H11NO6S, forms enanti­opure crystals in the monoclinic space group P21 and exists as a zwitterion, with a protonated α-amino group and a deprotonated α-carboxyl group. Both the carboxyl groups and the amino group are involved in an extensive multicentered inter­molecular hydrogen-bonding scheme. In the crystal, the diperiodic network of hydrogen bonds propagates parallel to (101) and involves inter­connected heterodromic R43(10) rings. Electrostatic forces are major contributors to the structure energy, which was estimated by DFT calculations as Etotal = −333.5 kJ mol−1.




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Poly[[{μ2-5-[(di­methyl­amino)(thioxo)meth­oxy]benzene-1,3-di­carboxyl­ato-κ4O1,O1':O3,O3'}(μ2-4,4'-di­pyridyl­amine-κ2N4:N4')cobalt(II)] di­methyl­formamide hemisolvate monohydrate]

In the crystal structure of the title compound, {[Co(C11H9NSO5)(C10H9N3)]0.5C3H7NO·H2O}n or {[Co(dmtb)(dpa)]·0.5DMF·H2O}n (dmtb2– = 5-[(di­meth­yl­amino)­thioxometh­oxy]-1,3-benzene­dicarboxyl­ate and dpa = 4,4'-di­pyridyl­amine), an assembly of periodic [Co(C11H9NSO5)(C10H9N3)]n layers extending parallel to the bc plane is present. Each layer is constituted by distorted [CoO4N2] octa­hedra, which are connected through the μ2-coordination modes of both dmtb2– and dpa ligands. Occupationally disordered water and di­meth­yl­formamide (DMF) solvent mol­ecules are located in the voids of the network to which they are connected through hydrogen-bonding inter­actions.




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Chlorido­[5,10,15,20-tetra­kis­(quinoline-7-carboxamido)­porphinato]iron(III)

The title compound, [Fe(C84H52N12O4)Cl], crystallizes in space group C2/c. The central FeIII cation (site symmetry 2) is coordinated in a fivefold manner, with four pyrrole N atoms of the porphyrin core in the basal sites and one Cl atom (site symmetry 2) in the apical position, which completes a slightly distorted square-pyramidal environment. The porphyrin macrocycle shows a characteristic ruffled-shape distortion and the iron atom is displaced out of the porphyrin plane by 0.42 Å with the average Fe—N distance being 2.054 (4) Å; the Fe—Cl bond length is 2.2042 (7) Å. Inter­molecular C—H⋯N and C—H⋯O hydrogen bonds occur in the crystal structure.




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(2,5-Di­methyl­imidazole){N,N',N'',N'''-[porphyrin-5,10,15,20-tetra­yltetra­(2,1-phenyl­ene)]tetra­kis(pyridine-3-carboxamide)}manganese(II) chloro­benzene disolvate

In the title compound, [Mn(C68H44N12O4)(C5H8N2)]·2C6H5Cl, the central MnII ion is coordinated by four pyrrole N atoms of the porphyrin core in the basal sites and one N atom of the 2,5-di­methyl­imidazole ligand in the apical site. Two chloro­benzene solvent mol­ecules are also present in the asymmetric unit. Due to the apical imidazole ligand, the Mn atom is displaced out of the 24-atom porphyrin mean plane by 0.66 Å. The average Mn—Np (p = porphyrin) bond length is 2.143 (8) Å, and the axial Mn—NIm (Im = 2,5-di­methyl­imidazole) bond length is 2.171 (8) Å. The structure displays inter­molecular and intra­molecular N—H⋯O, N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonding. The crystal studied was refined as a two-component inversion twin.




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trans-Di­aqua­tetra­kis­(tetra­hydro­furan-κO)iron(II) μ-carbonyl-tetra­deca­carbonyl­tetra­chlorido-μ-di­methyl­silanediolato-tetra­galliumtetra­iron(7 Ga–Fe)(Fe–Fe) tetra­hydro&#

The title compound, [Fe(C4H8O)4(H2O)2][Fe4Ga4(C2H6O2Si)Cl4(CO)15]·4C4H8O, consists of an iron(II) cation octa­hedrally coordinated by two water mol­ecules (trans) with four tetra­hydro­furans (THF) at equatorial sites. Two additional THF mol­ecules are hydrogen bonded to each of the water mol­ecules. The dianion of the title compound is an organometallic butterfly complex with a dimethyl siloxane core and two iron-gallium fragments. The lengths of the iron to gallium metal–metal bonds range from 2.3875 (6) to 2.4912 (6) Å.




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Dicarbonyl-1κ2C-μ-chlorido-2:3κ2Cl:Cl-penta­chlorido-2κ2Cl,3κ3Cl-[1(η6)-toluene]digallium(III)ruthenium(I)(Ru—Ga)

The title compound, [RuGa2Cl6(C7H8)(CO)2] or [(CO)2(GaCl2)(η6-toluene)Ru]+[GaCl4]−, was isolated from the reaction of Ga2Cl4 with di­phenyl­silanediol in toluene, followed by the addition of Ru3(CO)12. The compound contains a ruthenium–gallium metal–metal bond with a length of 2.4575 (2) Å.




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Methyl 2-[(Z)-5-bromo-2-oxoindolin-3-yl­idene]­hydrazinecarbodi­thio­ate

The title compound, C10H8BrN3OS2, a brominated di­thio­carbazate imine deriv­ative, was obtained from the condensation reaction of S-methyl­dithio­carbazate (SMDTC) and 5-bromo­isatin. The essentially planar mol­ecule exhibits a Z configuration, with the di­thio­carbazate and 5-bromo­isatin fragments located on the same sides of the C=N azomethine bond, which allows for the formation of an intra­molecular N—H⋯Ob (b = bromo­isatin) hydrogen bond generating an S(6) ring motif. In the crystal, adjacent mol­ecules are linked by pairs of N—H⋯O hydrogen bonds, forming dimers characterized by an R22(8) loop motif. In the extended structure, mol­ecules are linked into a three-dimensional network by C—H⋯S and C—H⋯Br hydrogen bonds, C—Br⋯S halogen bonds and aromatic π–π stacking.




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Bis(2-carb­oxy­quinolinium) hexa­chlorido­stan­nate(IV) dihydrate

In the hydrated title salt, (C10H8NO2)2[SnCl6]·2H2O, the tin(IV) atom is located about a center of inversion. In the crystal structure, the organic cation, the octa­hedral inorganic anion and the water mol­ecule of crystallization inter­act through O—H⋯O, N—H⋯O and O—H⋯Cl hydrogen bonds, supplemented by weak π–π stacking between neighboring cations, and C—Cl⋯π inter­actions.




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Redetermined structure of methyl 3-{4,4-di­fluoro-2-[2-(methoxy­car­bon­yl)­ethyl]-1,3,5,7-tetra­methyl-4-bora-3a,4a-di­aza-s-in­da­cen-6-yl}pro­pion­ate

In the title compound, C21H27BF2N2O4, a highly fluorescent boron–dipyrromethene dye, the methyl­propionate moieties have different conformations. In the crystal, weak C—H⋯F and C—H⋯O inter­actions link the mol­ecules. Some optical properties are presented.




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(1R,2S,4aR,6S,8R,8aS)-1-(3-Hy­droxy­propano­yl)-1,3,6,8-tetra­methyl-1,2,4a,5,6,7,8,8a-octa­hydronaphthalene-2-carb­oxy­lic acid

The mol­ecular structure of C18H28O4, (+)-diplodiatoxin, is described, whereby the absolute configuration of the structure of diplodiatoxin has been confirmed by single-crystal X-ray diffraction. Diplodiatoxin crystallizes in the chiral P43212 space group with one mol­ecule in the asymmetric unit.




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Methyl 2-[(Z)-5-methyl-2-oxoindolin-3-yl­idene]hydrazinecarbodi­thio­ate

The title di­thio­carbazate imine, C11H11N3OS2, was obtained from the condensation reaction of S-methyl­dithio­carbazate (SMDTC) and 5-methyl­isatin. It shows a Z configuration about the imine C=N bond, which is associated with an intra­molecular N—H⋯O hydrogen bond that closes an S(6) ring. In the crystal, inversion dimers linked by pairwise N—H⋯O hydrogen bonds generate R22(8) loops. The extended structure features C—H⋯S contacts as well as reciprocal carbon­yl–carbonyl (C=O⋯C=O) inter­actions.




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1-Eth­oxy-3-[4-(eth­oxy­carbon­yl)phen­yl]-3-hy­droxy-1-oxopropan-2-aminium chloride

The title compound, C14H20NO5+·Cl−, was prepared as a racemate of R,R- and S,S-enanti­omers by reduction of the corresponding hy­droxy­imino­ketone. In the crystal, layers are formed via hydrogen bridges of four ammonium groups to chloride ions; these lamellae are connected via inter­digitated benzoic ester groups.




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2-Amino-5-oxo-4-(thio­phen-2-yl)-5,6,7,8-tetra­hydro-4H-chromene-3-carbo­nitrile

The crystal structure of the title compound, C14H12N2O2S, reveals two symmetrically independent mol­ecules within the asymmetric unit. Each mol­ecule contains a chromenone core attached to a 2-thio­phene ring, cyano, and amino groups. The 2-thio­phene ring of one of the two mol­ecules in the asymmetric unit was found to be disordered over two positions, with the major component having a site occupancy factor of 0.837 (2). The 2-thio­phene ring is nearly orthogonal to the fused 4H-pyran ring, with dihedral angles between the two sets of planes being 89.5 (5) and 89.63 (8)°. Inter­molecular hydrogen bonding, involving N—H⋯N and N—H⋯O inter­actions, creates two distinct motifs leading to the formation of a two-dimensional supra­molecular network along the crystallographic ac plane.




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Structural insights into 1,4-bis­(neopent­yloxy)pillar[5]arene and the pyridine host–guest system

The crystal structure of 1,4-bis­(neopent­yloxy)pillar[5]arene, C95H140N2O10 (TbuP), featuring two encapsulated pyridine mol­ecules, reveals significant host–guest inter­actions. Inter­estingly, the pyridine guests are positioned near the neopent­yloxy substituents instead of the electron-rich aromatic core of the pillar[5]arene. This spatial arrangement suggests a preference for the pyridine mol­ecules to engage with the aliphatic regions of the host. Detailed analysis of the structural characteristics of this host–guest system (TbuP·2Py), as well as its packing pattern within the crystal network, is presented and discussed.




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Crystal structure and analytical profile of 1,2-di­phenyl-2-pyrrolidin-1-yl­ethanone hydro­chloride or `α-D2PV': a synthetic cathinone seized by law enforcement, along with its diluent sugar, myo-inositol

A confiscated package of street drugs was characterized by the usual mass spectral (MS) and FT–IR analyses. The confiscated powder material was highly crystalline and was found to consist of two very different species, accidentally of sizes convenient for X-ray diffraction. Thus, one each was selected and redundant com­plete sets of data were collected at 100 K using Cu Kα radiation. The selected crystals contained: (a) 1,2-diphenyl-2-(pyrrolidin-1-yl)ethanone hy­dro­chloride hemihydrate or 1-(2-oxo-1,2-di­phenyl­eth­yl)pyrrolidin-1-ium chloride hemihydrate, C18H20NO+·Cl−·0.5H2O, (I), a synthetic cathinone called `α-D2PV', and (b) the sugar myo-inositol, C6H12O6, (II), probably the only instance in which the drug and its diluent have been fully characterized from a single confiscated sample. Moreover, the structural details of both are rather attractive showing: (i) inter­esting hydrogen bonding observed in pairwise inter­actions by the drug mol­ecules, mediated by the chloride counter-anions and the waters of crystallization, and (ii) π–π inter­actions in the case of the phenyl rings of the drug which are of two different types, namely, π–π stacking and edge-to-π. Finally, the inositol crystallizes with Z' = 2 and the resulting diastereoisomers were examined by overlay techniques.




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Synthesis, crystal structure and in-silico evaluation of aryl­sul­fon­amide Schiff bases for potential activity against colon cancer

This report presents a comprehensive investigation into the synthesis and characterization of Schiff base com­pounds derived from benzene­sul­fon­amide. The synthesis process, involved the reaction between N-cyclo­amino-2-sulf­anil­amide and various substituted o-salicyl­aldehydes, resulted in a set of com­pounds that were subjected to rigorous characterization using advanced spectral techniques, including 1H NMR, 13C NMR and FT–IR spectroscopy, and single-crystal X-ray diffraction. Furthermore, an in-depth assessment of the synthesized com­pounds was conducted through Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) analysis, in conjunction with docking studies, to elucidate their pharmacokinetic profiles and potential. Impressively, the ADMET analysis showcased encouraging drug-likeness properties of the newly synthesized Schiff bases. These computational findings were substanti­ated by mol­ecular properties derived from density functional theory (DFT) calculations using the B3LYP/6-31G* method within the Jaguar Module of Schrödinger 2023-2 from Maestro (Schrodinger LLC, New York, USA). The ex­plor­ation of frontier mol­ecular orbitals (HOMO and LUMO) enabled the computation of global reactivity descriptors (GRDs), encompassing charge separation (Egap) and global softness (S). Notably, within this analysis, one Schiff base, namely, 4-bromo-2-{N-[2-(pyr­rol­idine-1-sul­fonyl)phenyl]car­box­imid­oyl}phenol, 20, em­erged with the smallest charge separation (ΔEgap = 3.5780 eV), signifying heightened potential for biological properties. Conversely, 4-bromo-2-{N-[2-(piper­idine-1-sul­fonyl)phenyl]car­box­imid­oyl}phenol, 17, exhibited the largest charge separation (ΔEgap = 4.9242 eV), implying a relatively lower propensity for biological activity. Moreover, the synthesized Schiff bases displayed re­marke­able inhibition of tankyrase poly(ADP-ribose) polymerase enzymes, integral in colon cancer, surpassing the efficacy of a standard drug used for the same purpose. Additionally, their bioavailability scores aligned closely with established medications such as trifluridine and 5-fluoro­uracil. The ex­plor­ation of mol­ecular electrostatic potential through colour mapping delved into the electronic behaviour and reactivity tendencies intrinsic to this diverse range of mol­ecules.




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Absolute structure determination of Berkecoumarin by X-ray and electron diffraction

X-ray and electron diffraction methods independently identify the S-enanti­omer of Berkecoumarin [systematic name: (S)-8-hy­droxy-3-(2-hy­droxy­prop­yl)-6-meth­oxy-2H-chromen-2-one]. Isolated from Berkeley Pit Lake Penicillium sp., Berkecoumarin is a natural product with a light-atom com­position (C13H14O5) that challenges in-house absolute structure determination by anomalous scattering. This study further demonstrates the utility of dynamical refinement of electron-diffraction data for absolute structure determination.




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Mol­ecular structure and selective theophylline com­plexation by conformational change of diethyl N,N'-(1,3-phenyl­ene)dicarbamate

The receptor ability of diethyl N,N'-(1,3-phenyl­ene)dicarbamate (1) to form host–guest com­plexes with theophylline (TEO) and caffeine (CAF) by mechanochemistry was evaluated. The formation of the 1–TEO com­plex (C12H16N2O4·C7H8N4O2) was preferred and involves the conformational change of one of the ethyl carbamate groups of 1 from the endo conformation to the exo conformation to allow the formation of inter­molecular inter­actions. The formation of an N—H⋯O=C hydrogen bond between 1 and TEO triggers the conformational change of 1. CAF mol­ecules are unable to form an N—H⋯O=C hydrogen bond with 1, making the conformational change and, therefore, the formation of the com­plex impossible. Conformational change and selective binding were monitored by IR spectroscopy, solid-state 13C nuclear magnetic resonance and single-crystal X-ray diffraction. The 1–TEO com­plex was characterized by IR spectroscopy, solid-state 13C nuclear magnetic resonance, powder X-ray diffraction and single-crystal X-ray diffraction.




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Rebuttal to the article Pathological crystal structures

A section in the Acta Crystallographica Section C article by Raymond & Girolami [Acta Cryst. (2023), C79, 445–455] stated that the product of the reaction of [(Cp*Rh)2(μ-OH)3]+ (Cp* is 1,2,3,4,5-penta­methyl­cyclo­penta­diene) with 1-methyl­thymine (1-MT) at pH 10 and 60 °C, to synthesize the anionic com­ponent [RhI(η1-N3-1-MT)2]−, was not an RhI com­plex, but rather an AgI com­plex, due to the use of silver triflate (AgOTf) to remove Cl− from [Cp*RhCl2]2 to synthesize [Cp*Rh(H2O)3](OTf)2, a water-soluble crystalline com­plex. We will clearly show that this premise, as stated, is invalid, while the authors have simply avoided several important facts, including that Cp*OH, a reductive elimination product, at pH 10 and 60 °C, was unequivocally identified, thus leading to the RhI anionic com­ponent [RhI(η1-N3-1-MT)2]−. More importantly, AgOH, from the reaction of NaOH at pH 10 with any potentially remaining AgOTf, after the AgCl was filtered off, would be insoluble in water. Furthermore, a control experiment with the inorganic com­plex Rh(OH)3, reacting with 1-methyl­thymine at pH 10, provided no product, and this bodes well for a similar fate with AgOTf and 1-methyl­thymine, i.e. at pH 10, AgOTf would again be converted to the water-insoluble AgOH; therefore, no reaction would occur! Finally, a 1H NMR spectroscopy experiment was carried out with synthesized and crystallized [Cp*Rh(H2O)3](OTf)2 in D2O at various pD values; at pD 8.65 no reaction took place, while at pD 13.6, and at 60 °C for 2 h, a reductive elimination reaction caused the precipitation of Cp*OH. The subsequent 1H NMR spectrum clearly demonstrated, in the absence of any AgI com­plexes, that the solution structure and the X-ray crystals in D2O were similar. A postulated mechanism for this novel anionic com­ponent structure, as published previously [Smith et al. (2014). Organometallics, 33, 2389–2404], will be presented, along with the experimental data, to insure the credibility of our results. We will also answer the comments in the response of Drs Raymond and Girolami to this rebuttal.




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Response to the rebuttal of the article Pathological crystal structures

We stand fully behind our earlier suggestion [Raymond & Girolami (2023). Acta Cryst. C79, 445–455] that the claim by Fish and co-workers [Chen et al. (1995). J. Am. Chem. Soc. 117, 9097–9098; Smith et al. (2014). Organometallics, 33, 2389–2404] of a linear two-coordinate rhodium(I) species is incorrect, and that the putative rhodium atom is in fact silver.




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Applying 3D ED/MicroED workflows toward the next frontiers

We report on the latest advancements in Microcrystal Electron Diffraction (3D ED/MicroED), as discussed during a symposium at the National Center for CryoEM Access and Training housed at the New York Structural Biology Center. This snapshot describes cutting-edge developments in various facets of the field and identifies potential avenues for continued progress. Key sections discuss instrumentation access, research applications for small mol­ecules and biomacromolecules, data collection hardware and software, data reduction software, and finally reporting and validation. 3D ED/MicroED is still early in its wide adoption by the structural science community with ample opportunities for expansion, growth, and innovation.




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Formation of extended polyiodides at large cation templates

By studying the structures of (μ-1,4,10,13-tetra­thia-7,16-di­aza­cyclo­octa­deca­ne)bis[iodidopalladium(II)] diiodide penta­(diiodine), [Pd2I2(C12H26N2S4)](I)2·5I2 or [Pd2I2([18]aneN2S4)](I)2·(I2)5, and 4,7,13,16,21,24-hexa­oxa-1,10-diazo­niabi­cyclo­[8.8.8]hexa­cosane triiodide iodide hemi­penta­(diiodine) di­chloro­methane mono­solvate, C18H38N2O62+·I3−·I−·2.5I2·CH2Cl2 or [H2([2.2.2]cryptand)](I3)(I)(I2)2.5·CH2Cl2, we confirm the structural variety of extended polyiodides achievable upon changing the shape, charge and dimensions of the cation template, by altering the synthetic strategy adopted and/or the experimental conditions. Although it is still often difficult to characterize discrete [I2m+n]n− polyiodides higher than I3− on the basis of structural parameters, such as I—I bond distances, FT–Raman spectroscopy appears to identify them as aggregates of I2, I− and (symmetric or slightly asymmetric) I3− building blocks linked by I⋯I inter­actions of varying strengths. However, because FT–Raman spectroscopy carries no information about the topological features of extended polyiodides, the two techniques should therefore be applied in combination to enhance the analysis of this kind of compounds.




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Synthesis, characterization and structural analysis of com­plexes from 2,2':6',2''-terpyridine derivatives with transition metals

The synthesis and structural characterization of three families of coordination com­plexes synthesized from 4'-phenyl-2,2':6',2''-terpyridine (8, Ph-TPY), 4'-(4-chloro­phen­yl)-2,2':6',2''-terpyridine (9, ClPh-TPY) and 4'-(4-meth­oxy­phen­yl)-2,2':6',2''-terpyridine (10, MeOPh-TPY) ligands with the divalent metals Co2+, Fe2+, Mn2+ and Ni2+ are reported. The com­pounds were synthesized from a 1:2 mixture of the metal and ligand, resulting in a series of com­plexes with the general formula [M(R-TPY)2](ClO4)2 (where M = Co2+, Fe2+, Mn2+ and Ni2+, and R-TPY = Ph-TPY, ClPh-TPY and MeOPh-TPY). The general formula and structural and supra­molecular features were determinated by single-crystal X-ray diffraction for bis­(4'-phenyl-2,2':6',2''-terpyridine)­nickel(II) bis­(per­chlo­rate), [Ni(C21H15N3)2](ClO4)2 or [Ni(Ph-TPY)2](ClO4)2, bis­[4'-(4-meth­oxy­phen­yl)-2,2':6',2''-terpyridine]­manganese(II) bis­(per­chlo­rate), [Mn(C22H17N3O)2](ClO4)2 or [Mn(MeOPh-TPY)2](ClO4)2, and bis­(4'-phenyl-2,2':6',2''-ter­py­ridine)­manganese(II) bis­(per­chlo­rate), [Mn(C21H15N3)2](ClO4)2 or [Mn(Ph-TPY)2](ClO4)2. In all three cases, the com­plexes present distorted octa­hedral coordination polyhedra and the crystal packing is determined mainly by weak C—H⋯π inter­actions. All the com­pounds (except for the Ni derivatives, for which FT–IR, UV–Vis and thermal analysis are reported) were fully characterized by spectroscopic (FT–IR, UV–Vis and NMR spectroscopy) and thermal (TGA–DSC, thermogravimetric analysis–differential scanning calorimetry) methods.




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Supra­molecular hy­dro­gen-bonded networks formed from copper(II) car­box­yl­ate dimers

The well-known copper car­box­yl­ate dimer, with four car­box­yl­ate ligands ex­ten­ding outwards towards the corners of a square, has been employed to generate a series of crystalline com­pounds. In particular, this work centres on the use of the 4-hy­droxy­benzoate anion (Hhba−) and its deprotonated phe­nol­ate form 4-oxidobenzoate (hba2−) to obtain complexes with the general formula [Cu2(Hhba)4–x(hba)xL2–y]x−, where L is an axial coligand (including solvent mol­ecules), x = 0, 1 or 2, and y = 0 or 1. In some cases, short hy­dro­gen bonds result in complexes which may be represented as [Cu2(Hhba)2(H0.5hba)2L2]−. The main focus of the investigation is on the formation of a variety of extended networks through hy­dro­gen bonding and, in some crystals, coordinate bonds when bridging coligands (L) are employed. Crystals of [Cu2(Hhba)4(di­ox­ane)2]·4(di­ox­ane) consist of the expected Cu dimer with the Hhba− anions forming hy­dro­gen bonds to 1,4-di­ox­ane mol­ecules which block network formation. In the case of crystals of com­position [Et4N][Cu2(Hhba)2(H0.5hba)2(CH3OH)(H2O)]·2(di­ox­ane), Li[Cu2(Hhba)2(H0.5hba)2(H2O)2]·3(di­ox­ane)·4H2O and [Cu2(Hhba)2(H0.5hba)2(H0.5DABCO)2]·3CH3OH (DABCO is 1,4-di­aza­bicyclo­[2.2.2]octa­ne), square-grid hy­dro­gen-bonded networks are generated in which the complex serves as one type of 4-con­necting node, whilst a second 4-con­necting node is a hy­dro­gen-bonding motif assembled from four phenol/phenolate groups. Another two-dimensional (2D) network based upon a related square-grid structure is formed in the case of [Et4N]2[Cu2(Hhba)2(hba)2(di­ox­ane)2][Cu2(Hhba)4(di­ox­ane)(H2O)]·CH3OH. In [Cu2(Hhba)4(H2O)2]·2(Et4NNO3), a square-grid structure is again apparent, but, in this case, a pair of nitrate anions, along with four phenolic groups and a pair of water mol­ecules, combine to form a second type of 4-con­necting node. When 1,8-bis­(di­methyl­amino)­naphthalene (bdn, `proton sponge') is used as a base, another square-grid network is generated, i.e. [Hbdn]2[Cu2(Hhba)2(hba)2(H2O)2]·3(di­ox­ane)·H2O, but with only the copper dimer complex serving as a 4-con­necting node. Complex three-dimensional networks are formed in [Cu2(Hhba)4(O-bipy)]·H2O and [Cu2(Hhba)4(O-bipy)2]·2(di­ox­ane), where the potentially bridging 4,4'-bi­pyridine N,N'-dioxide (O-bipy) ligand is employed. Rare cases of mixed car­box­yl­ate copper dimer complexes were obtained in the cases of [Cu2(Hhba)3(OAc)(di­ox­ane)]·3.5(di­ox­ane) and [Cu2(Hhba)2(OAc)2(DABCO)2]·10(di­ox­ane), with each structure possessing a 2D network structure. The final com­pound re­por­ted is a simple hy­dro­gen-bonded chain of com­position (H0.5DABCO)(H1.5hba), formed from the reaction of H2hba and DABCO.




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Crystal structure and cryomagnetic study of a mononuclear erbium(III) ox­am­ate inclusion com­plex

The synthesis, crystal structure and magnetic properties of an ox­am­ate-con­taining erbium(III) com­plex, namely, tetra­butyl­ammonium aqua­[N-(2,4,6-tri­methyl­phen­yl)oxamato]erbium(III)–di­methyl sulfoxide–water (1/3/1.5), (C16H36N)[Er(C11H12NO3)4(H2O)]·3C2H6OS·1.5H2O or n-Bu4N[Er(Htmpa)4(H2O)]·3DMSO·1.5H2O (1), are reported. The crystal structure of 1 reveals the occurrence of an erbium(III) ion, which is surrounded by four N-phenyl-substituted ox­am­ate ligands and one water mol­ecule in a nine-coordinated environment, together with one tetra­butyl­ammonium cation acting as a counter-ion, and one water and three dimethyl sulfoxide (DMSO) mol­ecules of crystallization. Variable-temperature static (dc) and dynamic (ac) magnetic mea­sure­ments were carried out for this mononuclear com­plex, revealing that it behaves as a field-induced single-ion magnet (SIM) below 5.0 K.




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Synthesis, spectroscopic and crystallographic characterization of various cymantrenyl thio­ethers [Mn{C5HxBry(SMe)z}(PPh3)(CO)2]

Starting from [Mn(C5H4Br)(PPh3)(CO)2] (1a), the cymantrenyl thio­ethers [Mn(C5H4SMe)(PPh3)(CO)2] (1b) and [Mn{C5H4–nBr(SMe)n}(PPh3)(CO)2] (n = 1 for com­pound 2, n = 2 for 3 and n = 3 for 4) were obtained, using either n-butyllithium (n-BuLi), lithium diiso­propyl­amide (LDA) or lithium tetra­methyl­piperidide (LiTMP) as base, followed by electrophilic quenching with MeSSMe. Stepwise consecutive reaction of [Mn(C5Br5)(PPh3)(CO)2] with n-BuLi and MeSSMe led finally to [Mn{C5(SMe)5}(PPh3)(CO)2] (11), only the fifth com­plex to be reported containing a perthiol­ated cyclo­penta­dienyl ring. The mol­ecular and crystal structures of 1b, 3, 4 and 11 were determined and were studied for the occurrence of S⋯S and S⋯Br inter­actions. It turned out that although some inter­actions of this type occurred, they were of minor importance for the arrangement of the mol­ecules in the crystal.




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3-[(Benzo-1,3-dioxol-5-yl)amino]-4-meth­oxy­cyclo­but-3-ene-1,2-dione: polymorphism and twinning of a precursor to an anti­mycobacterial squaramide

The title compound, 3-[(benzo-1,3-dioxol-5-yl)amino]-4-meth­oxy­cyclo­but-3-ene-1,2-dione, C12H9NO5 (3), is a precursor to an anti­mycobacterial squaramide. Block-shaped crystals of a monoclinic form (3-I, space group P21/c, Z = 8, Z' = 2) and needle-shaped crystals of a triclinic form (3-II, space group P-1, Z = 4, Z' = 2) were found to crystallize concomitantly. In both crystal forms, R22(10) dimers assemble through N—H⋯O=C hydrogen bonds. These dimers are formed from crystallographically unique mol­ecules in 3-I, but exhibit crystallographic Ci symmetry in 3-II. Twinning by pseudomerohedry was encountered in the crystals of 3-II. The conformations of 3 in the solid forms 3-I and 3-II are different from one another but are similar for the unique mol­ecules in each polymorph. Density functional theory (DFT) calculations on the free mol­ecule of 3 indicate that a nearly planar conformation is preferred.




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Na[GeF5]·2HF: the first quarternary phase in the H–Na–Ge–F system

The structure of cis- or trans-bridged [GeF5]− anionic chains have been investigated [Mallouk et al. (1984). Inorg. Chem. 23, 3160–3166] showing the first crystal structures of μ-F-bridged penta­fluoro­germanates. Herein, we report the second crystal structure of trans-penta­fluoro­germanate anions present in the crystal structure of sodium trans-penta­fluoro­germanate(IV) bis­(hy­dro­gen fluoride), Na[GeF5]·2HF. The crystal structure [ortho­rhom­bic Pca21, a = 12.3786 (3), b = 7.2189 (2), c = 11.4969 (3) Å and Z = 8] is built up from infinite chains of trans-linked [GeF6]2− octa­hedra, extending along the b axis and spanning a network of penta­gonal bipyramidal distorted Na-centred polyhedra. These [NaF7] polyhedra are linked in a trans-edge fashion via hy­dro­gen fluoride mol­ecules, in analogy to already known sodium hy­dro­gen fluorides and potassium hy­dro­gen fluorides.




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Synthesis of organotin(IV) heterocycles containing a xanthenyl group by a Barbier approach via ultrasound activation: synthesis, crystal structure and Hirshfeld surface analysis

A series of organotin heterocycles of general formula [{Me2C(C6H3CH2)2O}SnR2] [R = methyl (Me, 4), n-butyl (n-Bu, 5), benzyl (Bn, 6) and phenyl (Ph, 7)] was easily synthesized by a Barbier-type reaction assisted by the sonochemical activation of metallic magnesium. The 119Sn{1H} NMR data for all four com­pounds confirm the presence of a central Sn atom in a four-coordinated environment in solution. Single-crystal X-ray diffraction studies for 17,17-dimethyl-7,7-di­phenyl-15-oxa-7-stanna­tetra­cyclo­[11.3.1.05,16.09,14]hepta­deca-1,3,5(16),9(14),10,12-hexa­­ene, [Sn(C6H5)2(C17H16O)], 7, at 100 and 295 K con­firmed the formation of a mono­nuclear eight-membered heterocycle, with a conformation depicted as boat–chair, resulting in a weak Sn⋯O inter­action. The Sn and O atoms are surrounded by hydro­phobic C—H bonds. A Hirshfeld surface analysis of 7 showed that the eight-membered heterocycles are linked by weak C—H⋯π, π–π and H⋯H noncovalent inter­actions. The pairwise inter­action energies showed that the cohesion between the heterocycles are mainly due to dispersion forces.




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2,4-Di­aryl­pyrroles: synthesis, characterization and crystallographic insights

Three 2,4-di­aryl­pyrroles were synthesized starting from 4-nitro­butano­nes and the crystal structures of two derivatives were analysed. These are 4-(4-meth­oxy­phen­yl)-2-(thio­phen-2-yl)-1H-pyrrole, C15H13NOS, and 3-(4-bromo­phen­yl)-2-nitroso-5-phenyl-1H-pyrrole, C16H11BrN2O. Although pyrroles without sub­stituents at the α-position with respect to the N atom are very air sensitive and tend to polymerize, we succeeded in growing an adequate crystal for X-ray diffraction analysis. Further derivatization using sodium nitrite afforded a nitrosyl pyrrole derivative, which crystallized in the triclinic space group Poverline{1} with Z = 6. Thus, herein we report the first crystal structure of a nitrosyl pyrrole. Inter­estingly, the co-operative hydrogen bonds in this NO-substituted pyrrole lead to a trimeric structure with bifurcated halogen bonds at the ends, forming a two-dimensional (2D) layer with inter­stitial voids having a radius of 5 Å, similar to some reported macrocyclic porphyrins.




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Coordination variety of phenyl­tetra­zolato and di­methyl­amido ligands in dimeric Ti, Zr, and Ta com­plexes

Three structurally diverse 5-phenyl­tetra­zolato (Tz) Ti, Zr, and Ta com­plexes, namely, (C2H8N)[Ti2(C7H5N4)5(C2H6N)4]·1.45C6H6 or (Me2NH2)[Ti2(NMe2)4(2,3-μ-Tz)3(2-η1-Tz)2]·1.45C6H6, (1·1.45C6H6), [Zr2(C7H5N4)6(C2H6N)2(C2H7N)2]·1.12C6H6·0.382CH2Cl2 or [Zr2(Me2NH)2(NMe2)2(2,3-μ-Tz)3(2-η1-Tz)2(1,2-η2-Tz)]·1.12C6H6·0.38CH2Cl2 (2·1.12C6H6·0.38CH2Cl2), and (C2H8N)2[Ta2(C7H5N4)8(C2H6N)2O]·0.25C7H8 or (Me2NH2)2[Ta2(NMe2)2(2,3-μ-Tz)2(2-η1-Tz)6O]·0.25C7H8 (3·0.25C7H8), where TzH is 5-phenyl-1H-tetra­zole, have been synthesized and structurally characterized. All three com­plexes are dinuclear; the Ti center in 1 is six-coordinate, whereas the Zr and Ta atoms in 2 and 3 are seven-coordinate. The coordination environments of the Ti centers in 1 are similar, and so are the ligations of the Ta centers in 3. In contrast, the two Zr centers in 2 bear a different number of ligands, one of which is a bidentate η2-5-phenyl­tetra­zolato ligand that has not been observed previously for d-block elements. The di­methyl­amido ligand, present in the starting materials, remained un­changed, or was converted to di­methyl­amine and di­methyl­ammonium during the synthesis. Di­methyl­amine coordinates as a neutral ligand, whereas di­methyl­ammonium is retained as a hy­dro­gen-bonded entity bridging Tz ligands.




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Methods in mol­ecular photocrystallography

Over the last three decades, the technology that makes it possible to follow chemical processes in the solid state in real time has grown enormously. These studies have important implications for the design of new functional materials for applications in optoelectronics and sensors. Light–matter inter­actions are of particular importance, and photocrystallography has proved to be an important tool for studying these inter­actions. In this technique, the three-dimensional structures of light-activated mol­ecules, in their excited states, are determined using single-crystal X-ray crystallography. With advances in the design of high-power lasers, pulsed LEDs and time-gated X-ray detectors, the increased availability of synchrotron facilities, and most recently, the development of XFELs, it is now possible to determine the structures of mol­ecules with lifetimes ranging from minutes down to picoseconds, within a single crystal, using the photocrystallographic technique. This review discusses the procedures for conducting successful photocrystallographic studies and outlines the different methodologies that have been developed to study structures with specific lifetime ranges. The com­plexity of the methods required increases considerably as the lifetime of the excited state shortens. The discussion is supported by examples of successful photocrystallographic studies across a range of timescales and emphasises the importance of the use of com­plementary analytical techniques in order to understand the solid-state processes fully.