Journal of Structural Chemistry最新文献

Gradient films of ternary BCN phases on a Si(100) substrate are prepared for the first time by plasma-enhanced chemical vapor deposition using trimethylamine borane complex and ammonia. The gradient character of films is provided by a stepwise ammonia content decrease at a constant synthesis temperature or by a stepwise temperature decrease at the constant initial composition of the gas phase. The reliability of the interpretation of experimental data obtained for the gradient films is verified using a specially prepared series of reference BCN films. Structural and chemical features of the reference and thickness-gradient films are studied by FTIR and Raman spectroscopy, HRTEM, SAED, and SEM/EDX. Several interesting nanostructures formed with different sequences and thickness are determined for both gradient films. The textural relationships between amorphous and nanocrystalline components of these films as well as chemical compositions of the latter are discussed in detail.

A copper(II) complex based on N-(2-pyridylmethyl)iminodiethane sulfonic acid is synthesized for the first time, and its structure is analyzed by single crystal X-ray diffraction (CCDC deposit No. 2431746). The coordination polymer is formed by [(Cu₂L₂(H₂O)₂)·6H₂O]_n monomer links in which the octahedral coordination environment of the metal center is composed of nitrogen atoms of pyridine and the amino group and oxygen atoms of the sulfo group and the water molecule, which are located in the equatorial plane. The axial positions contain oxygen atoms of the sulfo group of the adjacent ligand and the neighboring molecule, which form the 1D coordination polymer. The Cu⋯Cu distances between the nearest atoms of the coordination polymer is 5.273 Å, and the second nearest copper atom is at a distance of 5.313 Å. Unit cell parameters are: a, b, c = 11.2986(5) Å, 21.3011(8) Å, 7.4884(4) Å; α, β, γ = 90.00°, 108.993(6)°, 90.00°.

Crystals of the [Co(en)₃][Co(NO₂)₆]·3H₂O (1) double complex salt (DCS) are prepared upon isothermal evaporation of an aqueous solution containing [Co(en)₃]Cl₃ and Na₃[Co(NO₂)₆] in the 1:1 molar ratio. The new compound is trigonal, space group R32, a = 12.9915(4) Å, c = 11.7113(4) Å, V = 1711.81(9) Å³. Its crystal structure is characterized by partial disorder due to the incompatibility local symmetry of the [Co(NO₂)₆]^3– anion and the overall symmetry of the structure. In contrast to most DCSs containing structurally similar [Co(NH₃)₆]³⁺ cation, the hydrate 1 is well soluble in water.

Results of the Rietveld X-ray diffraction analysis are presented for PbZr_0.53Ti_0.47O₃, Pb_0.95Sr_0.05Zr_0.53Ti_0.47O₃, PZT-19, and PZT-23 samples along with the results of studying their dielectric, piezo-, and pyroelectric properties. The samples are found to consist of a mixture of solid solutions having the perovskite structure with tetragonal (T), monoclinic (M), and rhombohedral (R) crystal lattices. Their weight fractions are 48T/39M/13R, 39T/61M, 49T/51M, and 72T/28M in the samples respectively. Main structural parameters of the phases are determined (unit cell symmetry and parameters of the phases, atomic coordinates and isotropic thermal displacements). The effect of the phase compositions of the samples on their electrophysical properties is discussed. Based on the results of the theoretical-group analysis, the conclusion is drawn that the observed differences in the ferroelectric and related (dielectric, piezoelectric) properties of the studied samples are due to: 1) concentration of monoclinic phase Cm, 2) structural parameters of the Cm phase.

The preparation, X-ray crystal structure, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis of the two organic adducts derived from the salicylamide and the carboxylic acids are reported. XRD and FTIR analysis illustrated that 1 is an organic salt, while 2 belongs to a cocrystal. Salt 1 adopts the monoclinic, space group Cc, with a = 20.2877(19) Å, b = 12.0739(11) Å, c = 10.2892(9) Å, α = 90°, β = 107.512(3)°, γ = 90°，V = 2403.5(4) Å³, Z = 8. The cocrystal 2 crystallizes into the triclinic, space group (Pbar{1}), with a = 6.4730(6) Å, b = 8.0829(8) Å, c = 10.4601(9) Å, α = 107.089(2)°, β = 105.638(2)°, γ = 90.8710(10)°, V = 501.10(8) Å³, Z = 1. Here, the salicylamide at 1, 2 are both involved in the multiple conventional H-bonds. Apart from the conventional H-bonds, the auxiliary extending associates of CH⋯Cl, CH⋯O, O⋯O, O⋯Cl, O⋯Br, and CH-π also show critical roles in the space extension. Analysis by the Hirshfeld surface provides extra insights into the prevalence of the various short contacts in the crystal structures. The (text{R}_{1}^{2})(5), (text{R}_{2}^{1})(7), (text{R}_{2}^{2})(8), (text{R}_{4}^{2})(8), (text{R}_{7}^{6})(26), (text{R}_{8}^{6})(32), and (text{R}_{8}^{8})(30) synthons were enclosed at the adducts. For the interplay of the conventional H-bonds plus the various non-covalent contacts, both adopt the 3D net. In conclusion, we demonstrat that 3D motifs can be constructed by the collective non-covalent interactions.

New coordination Ni(II), Zn(II), and Cd(II) compounds with 1-(5-methyl-1H-pyrazol-3-yl)-1,2,3-triazole-4-carboxylic acid (H₂L) are prepared and characterized. It is established by SCXRD that [Ni(HL)₂(H₂O)₂]·2H₂O and [Zn(HL)₂(H₂O)₂]·2H₂O are isostructural discrete complexes with a ligand coordinated in the N,O-bidentate chelate mode. A [Zn(HL)₂]_n 1D metal-organic framework with bridging carboxylate groups is prepared by changing the synthesis conditions. The interaction of H₂L with cadmium perchlorate leads to the formation of the [Cd(HL₂]_n layered 2D metal-organic framework bearing a ligand coordinated in the N,O,O-tridentate mode via the pyrazole ring′s nitrogen atom and the bridging carboxylate group. The cadmium coordination polymer exhibits two-band luminescence with maxima at 460 nm and 530 nm.

We report the synthesis and characterization of two new rhenium(I) complexes [ReBr(CO)₃(L)] (1) and [Re(CO)₃(L)(m-XylylNC)]OTf (2), where m-XylylNC is 2,6-dimethylphenylisocyanide. These compounds are derived from the dipyrido[3,2-a:2′,3′-c]phenazine ligand functionalized with borneol group at the second position (m-XylylNC = 2,6-dimethylphenyl isocyanide). As determined by single crystal X-ray diffraction, the molecular structure of the 2 cation has a distorted octahedral geometry at the rhenium center coordinated by N,N′-chelating ligand L, one isonitryl and three carbonyl ligands.

The X-ray diffraction analysis of Sc(thd)₃ single crystals (thd is 2,2,6,6-tetramethylheptane-2,4-dionate) and Sc(thd)₃ and Fe(thd)₃ solid solutions is performed in the temperature range of 90-300 K. The new crystalline modification of Sc(thd)₃ is found in the range of 90-170 K (space group (Pbar{1})) and a phase transition is detected at 170 K. The DSC analysis of the Sc(thd)₃ samples reveals that a smeared thermal anomaly with the signal maximum at T_max = 176.4 K corresponds to the phase transition with a change in the space group. It is demonstrated that in comparison with Fe(thd)₃, the phase transition occurs in Sc(thd)₃ at a lower temperature, and the second phase transition is not observed up to 90 K. In the study of the crystals of Sc(thd)₃:Fe(thd)₃ solid solutions with component ratios of 1:7, 1:3, 1:1, and 3:1 at different temperatures it is established that the phase transition temperature increases with an increase in the Fe fraction in the crystal.

The synthesis of Zn_0.3Ni_0.7–xCo_xFe₂O₄ ferrites, where x = 0 – 0.7, is presented along with the results of studying their structures and microwave properties. These results show that cobalt substitution for nickel increases the unit cell parameter of the crystal lattice. The magnetic permittivity spectra contains two resonance peaks: low-frequency (1.31-2.04 GHz) related to the motion of domain boundaries and high-frequency (4.78-12.05 GHz) corresponding to the natural ferromagnetic resonance. An increase in the cobalt concentration shifts both resonances to higher frequencies. The Curie temperature of ferrites monotonically decreases as the cobalt concentration increases.

The polymorphism of pinaverium bromide has been further explored by characterizing two novel crystalline forms: a solvate with isopropanol and a dihydrate. The crystal structures of both forms were determined using single crystal X-ray diffraction. These new forms are compared to the previously reported anhydrous polymorph [1]. All three forms exhibit distinct packing motifs, crystal systems, and intermolecular interactions. The solvate crystallizes in the triclinic system with the inclusion of two isopropanol molecules per asymmetric unit, the dihydrate adopts a triclinic arrangement involving two water molecules in a hydrogen-bonded network. Structural analysis highlights the role of solvent interactions in crystal stabilization and polymorph selection. These findings contribute to a deeper understanding of the solid-state behaviour of pinaverium bromide, a clinically used antispasmodic agent [2, 3].