Acta Crystallographica Section C Structural Chemistry最新文献

Two crystal structures of bis(2,3,5,6-tetramethylphenyl)phosphine, C₂₀H₂₇P, are reported constituting the first recorded case of polymorphism in a secondary phosphine (R₂PH). The two structures differ in their conformation and, as a result, the steric hindrance experienced at the phosphorus centre is observed to be dependent on the packing environment. Each polymorph exhibits a distinct supramolecular structure; in polymorph I the molecules are arranged in columns in two directions, whereas polymorph II forms layers. There is a distinct lack of significant intermolecular interactions in either form, with the exception of some weak Me...π interactions observed in polymorph II. These interactions are likely the cause of the variation in the C-P-C angles observed between the two structures.

In this study, we present a new N-derivative of L-phenylalanine with 2-naphthaldehyde (PN), obtained by the Schiff base formation procedure and its subsequent reduction. This compound was crystallized as a zwitterion {2-[(naphthalen-2-ylmethyl)azaniumyl]-3-phenylpropanoate, C₂₀H₁₉NO₂}, as an anion in a sodium salt (catena-poly[[diaquasodium(I)-di-μ-aqua] 2-[(naphthalen-2-ylmethyl)amino]-3-phenylpropanoate monohydrate], {[Na(H₂O)₄](C₂₀H₁₈NO₂)·H₂O}_n), as a cation in a chloride salt [(1-carboxy-2-phenylethyl)(naphthalen-2-ylmethyl)azanium chloride acetic acid monosolvate, C₂₀H₂₀NO₂⁺·Cl^-·CH₃COOH], and additionally acting as a ligand in the pentacoordinated zinc compound aquabis{2-[(naphthalen-2-ylmethyl)amino]-3-phenylpropanoato-κO}zinc(II), [Zn(C₂₀H₁₈NO₂)₂(H₂O)] or [Zn(PN)₂(H₂O)], denoted (PN-Zn), with the amino acid derivative in its carboxylate form. Interestingly, both enantiomers of the zinc complex co-exist within the crystalline structure, one constructed by the ligands with the L (or S) configuration and the other with the ligands having the D (or R) configuration, represented as L,L-PN-Zn and D,D-PN-Zn, respectively. Also, in the structure of the zwitterion, the racemate L,D is observed. These results imply that chirality inversion of the amino acid derivative synthesized from enantiomerically pure L-phenylalanine is taking place, a phenomenon known as oscillatory transenantiomerization. The analysis of these crystal structures reveals that they are primarily stabilized through electrostatic interactions assisted by hydrogen bonds. An interesting finding is that the conformation of PN varies along this family: it is unfolded in the zwitterionic and cationic forms, and folded in the anionic form. To evaluate such conformational differences, we propose the use of a dimensionless Shape Factor quantity defined as the Structural Aspect Ratio (SA_R), computed from the geometrical features of the parallelepiped that tightly encloses a conformer constructed by rigid spheres. This parameter provides a simple but useful tool to distinguish conformational differences, providing insights that complement traditional structural analyses. The study of the structural features, conformational diversity, chirality and supramolecular properties of these compounds is also supported by density functional theory (DFT) calculations.

The article by Guzmán-Hernández & Jancik [(2024). Acta Cryst. C80, 766-774] is an excellent example of how QC-QCT (quantum crystallography-quantum chemical topology) methodology can extract structural information from a crystal.

Acyl fluorides and acyl cations represent typical reactive intermediates in organic reactions, such as Friedel-Crafts acylation. However, the comparatively stable phenyl-substituted compounds have not been fully characterized yet, offering a promising backbone. Attempts to isolate the benzoacylium cation have only been carried out starting from the acyl chloride with weaker chloride-based Lewis acids. Therefore, only adducts of 1,4-stabilized acyl cations could be obtained. Due to the low melting point of benzoyl fluoride, together with its volitality and sensitivity toward hydrolysis, the structures of the acyl fluoride and its acylium cation have not been determined. Herein, we report the first crystal structure of benzoyl fluoride, C₇H₅FO or PhCOF (monoclinic P2₁/n, Z = 8) and the benzoacylium undecafluorodiarsenate, C₇H₅O⁺·As₂F₁₁^- or [PhCO]⁺[As₂F₁₁]^- (monoclinic P2₁/n, Z = 4). The compounds were characterized by low-temperature vibrational spectroscopy and single-crystal X-ray analysis, and are discussed together with quantum chemical calculations. In addition, their specific π-interactions were elucidated.

Lithium-sulfur batteries are a promising candidate for the next generation of rechargeable batteries. Despite extensive research on this system over the last decade, a complete understanding of the phase transformations has remained elusive. Conventional in-situ powder X-ray diffraction has struggled to determine the unit cell and space group of the polysulfides formed during charge and discharge cycles due to the high solubility of these solid products in the liquid electrolyte. With the improvement in in-situ electrochemical set-ups dedicated to transmission electron microscopes, three-dimensional electron diffraction (3D ED) has the potential to capture the crystal structures of the polysulfides during cycling. In this work, the structure solution and refinement from 3D ED data of elemental sulfur, known to sublimate in the vacuum of transmission electron microscopes, is enabled through the use of an environmental cell with a micro-electromechanical system. This work represents the first step in characterizing sulfur's transformation into lithium polysulfides using in-situ 3D ED.

Three alkali metal salt forms of the diuretic chlorothiazide (systematic name: 6-chloro-1,1-dioxo-2H-1,2,4-benzothiazine-7-sulfonamide, HCTZ) are described. When crystallized from aqueous solution, the Na and K salts, namely, poly[[μ-aqua-aqua(μ₃-6-chloro-1,1-dioxo-7-sulfamoyl-2H-1,2,4-benzothiadiazin-2-ido)sodium] hemihydrate], {[Na(C₇H₅ClN₃O₄S₂)(H₂O)₂]·0.5H₂O}_n, and poly[[diaqua(μ₅-6-chloro-1,1-dioxo-7-sulfamoyl-2H-1,2,4-benzothiadiazin-2-ido)potassium] hemihydrate], {[K(C₇H₅ClN₃O₄S₂)(H₂O)₂]·0.5H₂O}_n, are both found to have stoichiometry MCTZ·2.5H₂O, with CTZ deprotonated at a heterocyclic ring N atom. Both the stoichiometry and the deprotonation site are different to those described in previously published versions of these structures. The Cs salt form is found to be the monohydrate CsCTZ·H₂O, namely, poly[[aqua(μ₅-6-chloro-1,1-dioxo-7-sulfamoyl-2H-1,2,4-benzothiadiazin-2-ido)caesium], [Cs(C₇H₅ClN₃O₄S₂)(H₂O)]_n. As with the Na and K cognates, this structure is also deprotonated at the heterocyclic ring. NaCTZ is found to be a two-dimensional coordination polymer with bridges between Na centres formed by H₂O and SO₂ groups, and by links through the length of the coordinated CTZ anions. Water ligands in KCTZ and CsCTZ are terminal, rather than bridging between metal centres, but both compounds form structures where M-Cl interactions link two-dimensional motifs formed via M-O bonds (and in CsCTZ, M-N bonds) into three-dimensional coordination polymers.

Three bisferrocene-based bis(acylthiourea) positional isomers, namely, 1,2-bis(ferrocenylcarbonylthioureido)benzene (1), 1,3-bis(ferrocenylcarbonylthioureido)benzene (2) and 1,4-bis(ferrocenylcarbonylthioureido)benzene (3), all [Fe₂(C₅H₅)₂(C₂₀H₁₆N₄O₂S₂)], have been synthesized via facile nucleophilic addition reactions of 2.3 equivalents of ferrocenoyl isothiocyanate with o-, m- and p-phenylenediamine, respectively. The structures of the three new synthesized isomers were fully characterized by ¹H NMR, ¹³C NMR, IR and UV-Vis spectroscopy, elemental analyses and cyclic voltammetry. In addition, the structures of acetone monosolvated compound 1 (1·CH₃COCH₃), as well as compounds 2 and 3, have been determined by single-crystal X-ray diffraction. A combination of intermolecular N-H...S and C-H...S hydrogen bonds connects the components of compound 1·CH₃COCH₃ into infinite helix chains. Two pairs of different N-H...S and C-H...S intermolecular hydrogen bonds, as well as N-H...O and C-H...π co-operating interactions, link the molecules of compound 2 into a two-dimensional network. In contrast, compound 3 displays a one-dimensional double-chain array via two intermolecular C-H...S hydrogen bonds. Therefore, the three reported positional isomers present unique individual crystal assemblies.

The monoprotonated species of 2-aminomalonyl difluoride, namely, 1,3-difluoro-1,3-dioxopropan-2-aminium dihydrogen trifluoride, [C₃H₄F₂NO₂][H₂F₃], was synthesized from sulfur tetrafluoride in anhydrous hydrogen fluoride (aHF) with [NH₄][C₃H₅NO₄] as the starting material. The solvent was removed and the salt was dissolved in aHF and crystallized. In the solid state, the three-dimensional network is built by medium-strong N-H...F hydrogen bonds and C...F contacts. This is the first structure determination of an aminoacyl difluoride and the second of an aminoacyl fluoride.

Methyl prop-2-ynoate (C₄H₄O₂) was investigated in the binary superacidic system HF/MF₅ (M = Sb or As) and dimethyl fumarate (C₆H₈O₄) in the superacidic system HF/SbF₅, as well as HF/BF₃. The starting materials methyl prop-2-ynoate and dimethyl fumarate were crystallized, the former for the first time. The protonated species of these esters, namely, (1-methoxyprop-2-yn-1-ylidene)oxidanium hexafluoroarsenate, C₄H₅O₂⁺ AsF₆^-, 1,4-dimethoxy-4-oxobut-2-en-1-ylidene]oxidanium tetrafluoroborate bis(hydrogen fluoride), C₆H₉O₄⁺ BF₄^- 2HF, and hemi{[1,4-dimethoxy-4-oxidaniumylidenebut-2-en-1-ylidene]oxidanium} undecafluorodiantimonate, 0.5C₆H₁₀O₄²⁺ Sb₂F₁₁^-, were characterized by single-crystal X-ray diffraction and Raman spectroscopy. The protonated species were recrystallized from anhydrous hydrogen fluoride. In the solid state of the monoprotonated species of methyl prop-2-ynoate and the diprotonated species of dimethyl fumarate, strong intramolecular O-H...F hydrogen bonds build a three-dimensional network. The monoprotonated species of dimethyl fumarate builds chains by strong O-H...O hydrogen bonds between the cations.

The DIALS package provides a set of tools for crystallographic data processing. The open-source nature of the project, and a flexible interface in which individual command-line programs each have a dedicated job, have enabled the adaptation of DIALS to a wide range of experiment types, including electron diffraction. Here we present detailed instructions for the use of DIALS to process chemical crystallography diffraction data from continuous rotation electron diffraction experiments. We demonstrate processing and structure solution from three different samples from three different instruments, including two commercial instruments dedicated to electron diffraction. Each instrument has a pixel array detector, allowing low-noise data to be obtained, resulting in high quality structures. Various new features were added to DIALS to simplify the workflow for these use cases. These are described in detail, along with useful program options for electron diffraction work.