Acta Crystallographica Section E: Crystallographic Communications最新文献

In the title compound, C₁₀H₈N₂·2C₆H₅NO₃, 4-nitro-phenol and 4,4'-bi-pyridine crystallized together in a 2:1 ratio in the space group P2₁/n. There is a hydrogen-bonding inter-action between the nitro-gen atoms on the 4,4'-bi-pyridine mol-ecule and the hydrogen atom on the hydroxyl group on the 4-nitro-phenol, resulting in trimolecular units. This structure is a polymorph of a previously reported structure [Nayak & Pedireddi (2016 ▸). Cryst. Growth Des. 16, 5966-5975], which differs mainly due to a twist in the 4,4'-bi-pyridine mol-ecule.

The mercury(II) halide complex [1,3-di-tert-butyl-2,4-bis-(tert-butyl-amino)-1,3,2λ⁵,4λ⁵-di-aza-diphosphetidine-2,4-diselone-κ² Se,Se']di-iodido-mercury(II)N,N-di-methyl-formamide monosolvate, [HgI₂(C₁₆H₃₈N₄P₂Se₂)]·C₃H₇NO or (1)HgI₂, 2, containing cis-[( ^t BuNH)(Se)P(μ-N ^t Bu)₂P(Se)(NH ^t Bu)] (1) was synthesized and structurally characterized. The crystal structure of 2 confirms the chelation of chalcogen donors to HgI₂ with a natural bite angle of 112.95 (2)°. The coordination geometry around mercury is distorted tetra-hedral as indicated by the τ₄ geometry index parameter (τ₄ = 0.90). In the mercury complex, the exocyclic tert-butyl-amido substituents are arranged in an (endo, endo) fashion, whereas in the free ligand (1), the exocyclic substituents are arranged in an (exo, endo) pattern. Compound 2 displays non-classical N-H⋯O hydrogen-bonding inter-actions with the solvent N,N-di-methyl-formamide. These inter-actions may introduce geometrical distortion and deviation from an ideal geometry. An isostructural HgBr₂ analogue containing cis-[( ^t BuNH)(S)P(μ-N ^t Bu)₂P(S)(NH ^t Bu)] was also synthesized and structurally characterized, CIF data for the compound being presented as supporting information.

The isolation and crystalline structure of N,N'-di-benzyl-ethyl-enedi-ammonium dichloride, C₁₆H₂₂N₂ ²⁺·2Cl^-, is reported. This was obtained as an unintended product of an attempted Curtius rearrangement that involved benzyl-amine as one of the reagents and 1,2-di-chloro-ethane as the solvent. Part of a series of reactions of a course-based undergraduate research experience (CURE), this was not the intended reaction outcome. The goal of the course was to engage students as active participants in a laboratory experience which applies the foundational techniques of a synthetic organic laboratory, using the Curtius rearrangement as a tool for the assembly of medicinally significant scaffolds. The isolation of the title compound, N,N'-di-benzyl-ethyl-enedi-ammonium dichloride, the result of the 1,2-di-chloro-ethane solvent outcompeting the Curtius iso-cyanate inter-mediate in the reaction with the nucleophilic amine, confirms the importance of conducting research at the undergraduate level where the outcome is not predetermined. The solid-state structure of N,N'-di-benzyl-ethyl-enedi-ammonium dichloride was found to feature an all-trans methyl-ene-ammonium backbone. Strong N-H⋯Cl hydrogen bonds and C-H⋯Cl inter-actions lead to a layered structure with pseudo-translational symmetry emulating a C-centered setting. Different phenyl torsion angles at each end of the mol-ecule enable a more stable packing by allowing stronger hydrogen-bonding inter-actions, leading to a more ordered but lower symmetry and modulated structure in P2₁/n.

Two new phenyl-sulfonyl-indole derivatives, namely, N-{[3-bromo-1-(phenyl-sulfon-yl)-1H-indol-2-yl]meth-yl}-N-(4-bromo-3-meth-oxy-phen-yl)benzene-sulfonamide, C₂₈H₂₂Br₂N₂O₅S₂, (I), and N,N-bis-{[3-bromo-1-(phenyl-sulfon-yl)-1H-indol-2-yl]meth-yl}benzene-sulfonamide, C₃₆H₂₇Br₂N₃O₆S₃, (II), reveal the impact of intra-molecular π-π inter-actions of the indole moieties as a factor not only governing the conformation of N,N-bis-(1H-indol-2-yl)meth-yl)amines, but also significantly influencing the crystal patterns. For I, the crystal packing is dominated by C-H⋯π and π-π bonding, with a particular significance of mutual indole-indole inter-actions. In the case of II, the mol-ecules adopt short intra-molecular π-π inter-actions between two nearly parallel indole ring systems [with the centroids of their pyrrole rings separated by 3.267 (2) Å] accompanied by a set of forced Br⋯O contacts. This provides suppression of similar inter-actions between the mol-ecules, while the importance of weak C-H⋯O hydrogen bonding to the packing naturally increases. Short contacts of the latter type [C⋯O = 3.389 (6) Å] assemble pairs of mol-ecules into centrosymmetric dimers with a cyclic R ₂ ²(13) ring motif. These findings are consistent with the results of a Hirshfeld surface analysis and together they suggest a tool for modulating the supra-molecular behavior of phenyl-sulfonyl-ated indoles.

The crystal structure of the title organic-inorganic hybrid salt, (C₁₃H₁₂N₃)₂[CdCl₄], (I), has been reported with four mol-ecules in the asymmetric unit in a monoclinic cell [Vassilyeva et al. (2021 ▸). RSC Advances, 11, 7713-7722]. While using two different aldehydes in the oxidative cyclization-condensation involving CH₃NH₂·HCl to prepare a new monovalent cation with the imidazo[1,5-a]pyridinium skeleton, a new polymorph was obtained for (I) in space group P1 and a unit cell with approximately half the volume of the monoclinic form. The structural configurations of the two crystallographically non-equivalent organic cations as well as the geometry of the moderately distorted tetra-hedral CdCl₄ ^2- dianion show minor changes. In the crystal, identically stacked cations and tetra-chloro-cadmate anions form separate columns parallel to the a axis. The loose packing of the anions leads to a minimal separation of approximately 9.53 Å between the metal atoms in the triclinic form versus 7.51 Å in the monoclinic one, indicating that the latter is packed slightly more densely. The two forms also differ by aromatic stacking motifs. Similar to the monoclinic polymorph, the triclinic one excited at 364 nm shows an intense unsymmetrical photoluminescent band with maximum at 403 nm and a full width at half maximum of 51 nm in the solid state.

The title mol-ecule, C₂₅H₂₃BrN₂O₂, adopts a cup shaped conformation with the distinctly ruffled imidazolidine ring as the base. In the crystal, weak C-H⋯O hydrogen bonds and C-H⋯π(ring) inter-actions form helical chains of mol-ecules extending along the b-axis direction that are linked by additional weak C-H⋯π(ring) inter-actions across inversion centres. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (51.0%), C⋯H/H⋯C (21.3%), Br⋯H/H⋯Br (12.8%) and O⋯H/H⋯O (12.4%) inter-actions. The volume of the crystal voids and the percentage of free space were calculated to be 251.24 ų and 11.71%, respectively, showing that there is no large cavity in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the stabilization is dominated by the dispersion energy.

This virtual collection is a celebration. It is a celebration of crystallography in Africa, and a celebration of the international crystallography community. It commemorates the founding of the African Crystallographic Association (AfCA), which was accepted as the newest Regional Associate of the International Union of Crystallography (IUCr) in 2023, the year of the 75th anniversary of the first IUCr Congress and General Assembly. The collection contains research articles authored by scientists across the African continent, as well as a selection of articles giving context to crystallography in Africa. These discuss history, collaboration between scientists and between associations, and various educational and outreach initiatives.