Journal of Structural Chemistry最新文献

(2R,3R)-5-(2-(Chloroacetoxy)-2-(3,4-diacetoxyphenyl)-4-oxochroman-3,7-diyl diacetate containing two symmetrically independent molecules in the crystal unit cell is analyzed by single crystal X-ray diffraction. Molecular coordination numbers are studied in the crystal structure together with the topology of nets of intermolecular contacts. Intermolecular interaction energies are calculated and Hirshfeld surfaces of symmetrically independent molecules are analyzed.

Two salts of 1,2-diaminobenzene (dab) as acceptor with the trichloroacetic acid and 4-nitro-phthalic acid as donor were prepared and featured by the multiple analytical techniques of FTIR, elemental analysis (EA), and single crystal X-ray diffraction (SCXRD). The structural studies tell that the cation and anion are joined together by the energetic N⁺–H⋯O^– H-bonds due to the transfer of the proton from the donor to the acceptor. The salts show well resolved proton transfer bands in the regions where neither the donor nor the acceptor has any IR peaks. Spectrophotomeric and crystallographic studies have ensured the formation of 2:1/1:1 salts. The chief non-covalent interactions were counted via the Hirshfeld surface analysis. Despite variations of the carboxylic acids, there both bore the strong intermolecular N–HO H-bonds. Apart from the strong classical H-bonds, other supramolecular associates of O–O, Cl–C/Cl–O/Cl–Cl, CH–O, C–π, and π–π are also involved in the spatial stretchings. The anionic C7 chain was built at 2 by the O–H⋯O H-bonds. The roles of these non-covalent contacts are made clear. For the combination of the weak contacts, both salts exhibited the 3D views.

A series of ZnZrF₆·nH₂O (n = 6, 5, 4, 2, 0) hexafluorozirconates is studied by ¹⁹F, ¹H NMR. Assignments are made for the obtained ¹⁹F MAS NMR signals. Behavior of the shape of NMR spectra and positions of their signals upon structural changes is considered depending on the composition and hydration degree of the cation. The obtained data are compared with known NMR data for fluorozirconates. The shapes of broad lines of the recorded spectra are analyzed, and their temperature dependence as a result of reorientational motions of water molecules (n = 2, 5), (text{ZrF}_{ 6}^{2-}) ions (n = 6), and ZnF₂(H₂O)₄ ions (n = 4) is considered.

Barium hexaferrites BaFe_12–xIn_xO₁₉ (where x varies from 0 to 5 with a step of 0.25) is prepared by the solid-phase synthesis conducted at 1400 °C for 5 h. The crystal lattice parameters and chemical compositions of the samples prepared are determined. Dielectric and magnetic permeability values are calculated for each sample with x = 0-1.25.

Supramolecular lanthanide complexes with cucurbituril [{Eu_xPr_1–x(H₂O)₅(NO₃)}₂CB[6]](NO₃)₄·HNO₃ 6H₂O (x = 0.25, 0.5, 0.75, structural type I) are prepared. Keeping these compounds over CaCl₂ results in a phase transition which is caused by partial loss of water molecules and leads to the formation of [{Eu_{x Pr1–x}(H₂O)₃(NO₃)₂}₂CB[6]](NO₃)₂HNO₃ (structural type II). The I to II transition takes 24 h and is reversible: when kept in water vapors for 2 h, II transforms completely into I. Luminescent properties of I and II are studied. Differences between the intensities of bands assigned to hypersensitive Eu-centered ⁵D₀ → ⁷F₂ transitions are due to the fact that coordination environments of the central atom are different and contain five (for I) and three (for II) aqualigands. Significantly higher quantum yield of II is due to the suppression of luminescence quenching by O–H vibrations.

Phase equilibria in the Li₂O–B₂O₃–LiF ternary system are studied. It is established that the LBO primary crystallization region has a narrow concentration interval limited by Li₃B₇O₁₂–LiF and Li₂B₈O₁₈–LiF lines. The hydropyrolysis of LiF in air is studied. It is shown experimentally that the decomposition of LiF from the LiBO₂–LiF melt at 800 °C is insignificant, but the LiF content decreases notably with time at 900 °C.

The reaction of zinc nitrate with 3,6-di-4-pyridyl-1,2,4,5-tetrazine (4-DPT), 3,6-di-3-pyridyl-1,2,4,5-tetrazine (3-DPT), and trans-β-hydromuconic acid (H₂TBHMA) yields new MOFs of the following compositions: [Zn(3-DPT)(DMF)(NO₃)₂] (1), [Zn(3-DPT)(TBHMA)]·(MeOH) (2·MeOH), and [Zn₂(4-DPT)₂(TBHMA)(NO₃)₂]·2MeOH (3·2MeOH). Structures of the compounds are studied by single crystal X-ray diffraction (CIF file CCDC Nos. 2450436(1), 2450437 (2), 2450438 (3)).

Two known polymorphic modifications of racemic isobornylacetamide (C2/c (1a) and P2₁/n (1b) space groups) are prepared quantitatively for the first time and are characterized in comparison with each other using physico-chemical methods such as low-temperature XRD, DSC, and IR spectroscopy. The alternation of molecules of opposite configurations in the H-bonded chain of the crystal of 1b leads to the formation of stronger hydrogen bonding than in the homo-chiral chain of the crystal of 1a (as is indicated by the XRD and IR spectroscopy data on the H-bond parameters) and a larger number of secondary interactions. Thermochemical parameters of both modifications are obtained for the first time by DSC, and it is shown that the 1b polymorph is thermodynamically preferable in the melting point region.

Polymorphism is an infrequent phenomenon in platinum group complexes. Surprisingly, we found a new monoclinic crystal modification (C2/c) of a relatively simple compound, platinum (II) acetate Pt₄(OCOMe)₈ (2) (monoclinic C2/c (2), monoclinic P2₁/c (3) and tetragonal P4₃2₁2 (4)). The polymorph was prepared by a novel synthetic protocol and structurally identified by single-crystal X-ray diffraction (SC-XRD) using synchrotron radiation X-ray source. Examination of the intermolecular interaction by Hirshfeld surface analysis of 2 and its comparison with another known polymorphs - monoclinic (P2₁/c, 3) and tetragonal (P4₃2₁2, 4) ones, - as well as analysis of packaging motifs revealed the responsibility of weak interactions for their formation.