Journal of Structural Chemistry最新文献

Molecular and crystal structures of the novel [Pd{(PhO)₂PS₂}₂] complex and the known [Pd{(EtO)₂PS₂}₂] complex are studied. According to the XRD data, [Pd{(RO)₂PS₂}₂] (R = Et, Ph) compounds crystallize in centrosymmetric space groups, and their crystal structures consist of mononuclear complex molecules. The ({{(text{EtO})}_{2}}text{PS}_{2}^{-}) and ({{(text{PhO)}}_{2}}text{PS}_{2}^{-}) ions perform an S,S′-donor bidentate-chelating function leading to the formation of square-planar PdS₄ coordination cores. The electronic absorption spectra of the solutions of these complexes are studied; the influence of the ({{(text{RO})}_{2}}text{PS}_{2}^{-}) ligand structure and the solvent polarity on the observed optical properties of the studied compounds is considered.

A fine crystalline sample of the cubic modification (space group (Iabar{3}), Z = 16) of gadolinium oxide (C-Gd₂O₃) is grown by the solution–melt technique. The single crystal X-ray diffraction analysis performed at 150 K and 298 K reveals a relative increase in the unit cell parameter by 0.08%. The parameter at 300 K is refined by two independent procedures: in Bond’s scheme (a = 10.8152(9) Å, relative error Δa/a = 8·10^–5) and by calibrating the equatorial circumference according to the external reference (a = 10.8145(6) Å, relative error Δa/a = 5.1·10^–5). The values obtained coincide within the experimental error with data for the polycrystalline reference described by the National Bureau of Standards of the United States. The dependence a(T) is studied in the range of 90-490 K with a step of 10 K. Experimental points are described by second degree polynomial a = 10.801 + 2.7·10^–5T + 6.0·10^–8T².

We report synthesis and crystal structure of a new copper molybdate oxosulfate Cu₆O₂(MoO₄)₃(SO₄). The new compound is obtained in evacuated silica ampoules at 675-725 °C. Cu₆O₂(MoO₄)₃(SO₄) is monoclinic, space group P2₁/m, a = 7.5208(4) Å, b = 6.8602(3) Å, c = 14.0019(7) Å, β = 93.471(5)°, V = 721.09(6) Å³, R₁ = 0.051. The 3D framework of the new compound consists of oxo-centered [OCu₃]⁴⁺ chains and MoO₄ and SO₄ tetrahedra. The structural motif of the new compound is related to the previously described fumarole minerals, glikinite Zn₃O(SO₄)₂ and vergasovaite Cu₃O(MoO₄)(SO₄). The crystal chemical peculiarities of this group of synthetic compounds and minerals are discussed.

Two isostructural mononuclear cadmium(II) and nickel(II) complexes [Cd(HL)₂(NCS)₂]∙4CH₃OH (1) and [Ni(HL)₂(NCS)₂]∙4CH₃OH (2), where HL is the zwitterionic form of the Schiff base 2,4-difluoro-6-[(2-pyrrolidin-1-ylethylimino)methyl]phenol (HL), were prepared and characterized by elemental analysis, infrared and electronic spectroscopy, as well as X-ray single crystal determination. In both complexes the metal atoms are in octahedral coordination. The Schiff base ligands are coordinate to the metal atoms through phenolate oxygen and imino nitrogen. Molecules of the complexes are stabilized by hydrogen bonds. The biological assay indicates that the complexes have good antimicrobial activities on the bacteria strains Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Staphylococcus aureus.

Single crystals of a new acentric barium iodide-thiocyanate tetrahydrate Ba(SCN)I·4H₂O (1) are prepared by the isothermal evaporation of aqueous solutions containing Ba(SCN)₂·3H₂O and BaI₂·2H₂O in the 1:1 molar ratio. The crystal structure of 1 is determined by XRD. The substance crystallizes in the orthorhombic unit cell, the I2mb space group, a = 7.4803(2) Å, b = 16.0959(4) Å, c = 24.0037(5) Å. The crystal motif is pseudo-layered and is formed by a packing of two types of layers, cationic and anionic ones, parallel to (010). The cationic layer is composed of distorted [BaS₂N₂(H₂O)₆] face-sharing 10-vertex polyhedra forming zigzag chains along the [100] axis. The neighboring chains are combined into a layer through common vertices corresponding to sulfur atoms. The anionic layer is formed by iodine atoms combined with the cationic layer into a 3D framework by O–H⋯I hydrogen bonds.

The {[CuCl(L)]·DMF}_n complex compound is prepared by the interaction of (E)-N′-(pyridin-2-ylmethylene)isonicotinohydrazide (L) with CuCl₂·2H₂O in ethanol. The obtained compound is characterized by elemental analysis and IR spectroscopy; its crystal structure is determined by XRD. The compound has a polymeric structure and is composed of {CuCl(L)} fragments connected into zigzag chains due to the coordination of the pyridine nitrogen of the L ligand of one fragment to the copper atom of the neighboring fragment. The copper ion has a distorted square-pyramidal coordination environment (∠NCuO = 155.71° and ∠NCuCl = 101.16°). The unit cell containing four {[Cu(L)Cl]·DMF} fragments is calculated within the quantum chemical approach of the density functional theory. The electronic structure is analyzed; the band structure and density of states diagrams are constructed. It is shown that the electronic structure has no band gap: the Fermi level virtually coincides with the highest occupied crystal orbital (HOCO) and is equal to –5.733 eV. The HOCO and the lowest unoccupied crystal orbital (LUCO) have similar compositions, but the contribution of p orbitals of the organic ligand is higher for the LUCO. The electron density Laplacian values at the critical points of Cu–N, Cu–Cl, and Cu–O bonds indicate that these bonds belong to the intermediate type with a predominant contribution of ionic bonding.

The crystal structure of a new complex of gold(III) with tetrakis-(4-cyanophenyl)porphyrin of composition [Au(TCNPP)][AuCl₄]·DMF is determined by single crystal X-ray diffraction. The structure contains a complex [Au(TCNPP)]⁺ cation and a complex [AuCl₄]^– anion in which the gold(III) atom is in the typical square environment; AuN₄ and AuCl₄ coordination cores respectively. Short intermolecular Au⋯Au and Au⋯Cl contacts are revealed between the mentioned complex ions whose nature is studied by quantum chemical calculations within the density functional theory (ωB97XD/DZP-DKH) and Bader’s topological analysis of the electron density distribution (QTAIM).

An all-atom model of the furfural molecule is proposed. The model is a system of two formally independent configurationally rigid fragments linked by a single covalent bond with a limited range of deformations. Using this model, structural and thermophysical characteristics (density, heat of evaporation, specific isobaric heat capacity, coefficients of isothermal compressibility and volumetric thermal expansion, dielectric constant) of liquid furfural at 298 K under atmospheric pressure are calculated by the Monte Carlo method. It is established that the fraction of trans-conformers at 298 K is 84.5% in the gas phase and as low as 32.3% in the liquid phase. The analysis of instantaneous and vibrationally averaged structures of the simulated system shows that the fraction of molecules participating in the formation of stack-type associates is 15-16%.

POMs modified with lanthanide metals combine the advantages of POMs and lanthanide metals, and show promising properties in the fields of luminescence, magnetism, catalysis, etc. Comparing with the classical Keggin-type POMs, the Preyssler-type POMs with larger size exhibit a rich spatial structure evolution, thereby offering potential for the synthesis of polyoxometalates with excellent properties. In this paper, the Preyssler-type POMs K_12.5Na_1.5[NaP₅W₃₀O₁₁₀] (P₅W₃₀) were selected as the research object, five polyoxometalates KNa{[Tb₄(H₂O)₃₂](NaP₅W₃₀O₁₁₀)}·24H₂O(1), KNa{[Eu₄(H₂O)₃₂](NaP₅W₃₀O₁₁₀)}· ·19H₂O(2), KNa{[La₄(H₂O)₂₄](NaP₅W₃₀O₁₁₀)}·22H₂O(3), KNa{[Gd₄(H₂O)₃₀](NaP₅W₃₀O₁₁₀)}·20H₂O(4), KNa{[Sm₄(H₂O)₂₄](NaP₅W₃₀O₁₁₀)}·21H₂O(5) were designed and synthesized with different lanthanide metals by hydrothermal synthesis method. The effects of pH value, stoichiometric ratio and reaction temperature on the synthesis were summarized. The crystal structures of five polyoxometalates were described, and the coordination environment of lanthanide metals was analyzed. PXRD, infrared spectra, thermogravimetric and fluorescence properties of these compounds were studied.

The influence of the size of the β-diketonate ligand substituent on the structure and thermal properties of volatile Ni(II) complexes is determined. To this aim, a corresponding heptanedione-3.5 (Hhd) derivative is prepared. The structures of [Ni₃(hd)₆] and its derivatives [Ni₄(OMe)₄(hd)₄(MeOH)₄] and [Ni₃(OH) (hd)₅(H₂O)]₂ are studied by XRD. The trinuclear complex is similar to its simplest β-diketonate analogue. Such a tetranuclear structure is typical for mixed-ligand alkoxy-β-diketonate divalent metal complexes, whereas the hexuclear structure is unique. Thermal properties of Ni(II) β-diketonates in the series L = RC(O)CHC(O)R, R = Me, Et, tBu are compared by the thermogravimetry method.