Home – Home – Jornals – Journal of Structural Chemistry 2015 number 5

Adsorption of aliphatic sulfide on the faces of a 1.4x1.4x2.1 nm anatase nanoparticle of the stoichiometry Ti₁₁₄O₂₂₈ with ideal (001) and (100) faces are considered in this work. Molecular adsorption on the (001) face proceeds with the enthalpy varying from -6 kcal/mol to -38 kcal/mol by coordinating the sulfide sulfur atom to titanium and oxygen atoms, with the most exothermic adsorption occurring on atoms of the edges between (001) and (010) or (100) faces. Molecular adsorption on the (100) face proceeds with the enthalpy varying from -18 kcal/mol to -30 kcal/mol by coordinating the sulfur atom to oxygen atoms or simultaneously to oxygen and titanium atoms. In molecular adsorption complexes the S-Ti coordination bond length is 2.56-2.69 Å and the S-O bond length is 2.35-2.57 Å. Dissociative adsorption is observed on the (100) face and proceeds with the enthalpy up to -23 kcal/mol by coordinating the thiyl group to titanium and oxygen atoms and the ethyl group to surface oxygen atoms.

The electronic energy spectrum of the crystal and its sublattices of the crystalline a-phase of zinc chloride, the density of states, the total and deformation density of the charge distribution of valence electrons are calculated from the first principles using the density functional method. Optical vibrational modes are also calculated.

A two-parameter molecular descriptor is proposed in the QSPR model. It relates the ionization energies of molecules with topological indices and integrated oscillator strengths. Integrated oscillator strengths are obtained from electron spectroscopy data in the UV and visible spectral ranges. The regularities obtained are confirmed by the statistical processing of the data by multiple regression analysis methods in series of 1,4-naphthoquinone, 1-oxyanthraquinone, and 1-(4- tret-butylphenoxy)-9,10-anthraquinone derivatives.

Based on the full optimized molecular geometric structures at the B3LYP/cc-pVTZ level, a new designed compound 5-nitro-2-nitratomethyl-1,2,3,4-tetrazole is investigated in order to look for high energy density compounds (HEDCs). The IR spectrum, the heat of formation (HOF), and frontier molecular orbitals are predicted. The detonation velocity and pressure are evaluated using Kamlet-Jacobs equations based on the theoretical density and condensed HOF. The bond dissociation energies (BDEs) and bond orders for the weakest bonds are analyzed to investigate the thermal stability of the title compound. The results show that the O ₁-N ₆ bond is the trigger bond. The crystal structure obtained by molecular mechanics belongs to the Pna 2 ₁ space group with lattice parameters Z = 4, a = 13.7565 Å, b = 12.4737 Å, c = 4.3445 Å.

A newly synthesized Schiff base 3,3'-dihydroxy-4,4'-[4,4'-diphenylmethanebis(nitrilomethylidyne)]-bis-phenol is characterized experimentally. Also, the geometry optimization for the tautomers, tautomerism and assignment of the IR bands and NMR chemical shifts of the Schiff base were performed using the DFT method. Good consistency between the theoretical and experimental results confirms the validity of the optimized geometry. Geometries of four possible tautomers are fully optimized. None of them has a planar structure, but each of the benzene rings is in a separate plane. In the most stable tautomer L1, the phenolic protons are engaged in the intramolecular-hydrogen bond with the azomethine nitrogen atoms. Tautomerization of L1 can occur in two different pathways which are computationally studied using DFT and the Atoms In Molecules (AIM) analysis. Both pathways have the same barrier energy.

Random sampling analysis on the molecular surface (RASMS) is used to describe the chemical structures of 35 HEPT derivatives as anti-HIV drugs. Here a quantitative structure activity relationship (QSAR) model is built by multiple linear regression (MLR). The estimation stability and prediction ability of the model are strictly analyzed by both internal and external validations. The correlation coefficients of the established MLR model, leave-one-out (LOO) cross-validation, and predicted values versus experimental ones of external samples were r ² = 0.851, = 0.746, and r ²(test) = 0.815 respectively. The satisfactory results show that RASMS can express the information related to the biological activity of HEPT derivatives.

Results of a theoretical study of the molecular structure of arglabin are pesented. Quantum chemical calculations of the geometry and physicochemical characteristics of arglabin are performed by the semi-empirical РМ6 method, the non-empirical Hartree-Fock method, and the hybrid B3LYP DFT method with 6-31G and 6-31G( d ) basis sets. By the B3LYP/6-31G( d ) method the vibrational frequencies and intensities of IR absorption bands of arglabin are also calculated and the detailed interpretation of the IR spectrum is given. The theoretical frequencies are well consistent with the experimental data.

The work presents Raman spectra of platelike crystals of the CuCrS ₂ compound, which were grown from polycrystalline CuCrS ₂ by the CVD method with an elementary iodine as a carrier. The spectra are measured in the temperature range of 5-300 K. Observed vibrational modes are assigned based on the temperature dependences of their frequencies. In the temperature range of magnetic ordering ( Т < 40 K) a weak increase is observed in the frequencies of totally symmetric vibrations, which is interpreted as a result of the phonon-magnon interaction.

Binuclear [Pt(bt)m-(N^S)] ₂ complexes (bt ^- is the deprotonated form of 2-phenylbenzothiazole, (N^S) ^- = 2-mercaptopyridineate, 2-mercaptopyrimidineate, 2-mercaptobenzothiazoleate, 2-mercaptobenzoxazoleate ions) are characterized by the following methods: X-ray crystallography, ¹Н and ¹⁹⁵Pt NMR spectroscopy, electronic absorption and emission spectroscopy, cyclic voltammetry. The occurrence of the Pt-Pt chemical bond and complexes in both crystalline state and solution in the form of cis -N _(bt),S-binding isomers with the asymmetrical arrangement of two cyclometalated and two bridging ligands is shown. Long-wavе absorption bands and luminescence of the complexes in the red spectral range are due to spin-allowed and spin-forbidden optical charge transfer transitions from the metal-metal bond to the metalated ligand. In cyclic voltammetry, two-electron redox waves of the complexes are attributed to metal- and ligand-centered processes involving s* HOMO and p*(bt) LUMO of the complexes.

Elemental analyses, single crystal X-ray diffraction method, and ¹H and ¹³C NMR spectral techniques are used to synthesize and characterize the crystal structure of 4-diethylamino-2-{[4-(3-methyl-3-phenyl-cyclobutyl)-thiazol-2-yl]-hydrazonomethyl}-phenol. In order to calculate the molecular geometry along with vibrational frequencies and the gauge including atomic orbital (GIAO) ¹H and ¹³C NMR chemical shift values of the title crystal structure in the ground state, the Hartree-Fock (HF) and density functional theory (DFT) methods with 6-311G( d,p ) basis sets are utilized. The assignments of the vibrational frequencies are calculated with the help of the potential energy distribution (PED) analysis using the VEDA 4 software. Experimental data are used for comparison. The molecule contains C-H⋯O intra-inter-molecular interactions.

The possibility of modifying carbon materials by RCVD and MOCVD of complex high-melting coatings consisting of the inner hafnium carbide layer and the outer iridium layer is studied. The morphological features, microstructure, and phase composition of the carbide and complex HfC-Ir coating on a carbon material are examined by scanning electron microscopy and powder X-ray diffraction analysis. The HfC coating is uniform, continuous, repeating the geometry of a carbon substrate. A scheme of chemical reactions describing the processes of hafnium transfer on carbon in the form of gaseous hafnium fluorides with a lower valence is proposed. The iridium coating consists of slightly elongated crystallites and has a good adhesion to the carbide layer.

The structure of two new ionic compounds of sparfloxacin (C ₁₉H ₂₂F ₂N ₄O ₃, SfH), SfH ₃[ZnCl ₄]×1.5H ₂O (I) and SfH ₃[CdBr ₄]×H ₂O (II), is determined. Crystallographic data are as follows: for I a = 14.505(3) Å, b = 12.615(3) Å, c = 29.118(7) Å, V = 5254(4)Å ³, space group Pbca , Z = 8; for II a = 13.2822(5) Å, b = 10.2564(4) Å, c = 21.3250(8) Å, b = 100.7248(4)°, V = 2854.3(3) Å ³, space group P 2 ₁/ n , Z = 4. The structures of the compounds are stabilized by intra- and intermolecular hydrogen bonds and the structure of I is additionally stabilized by the p-p interaction between the SfH ions.

Ammonium dicobalt(II)-octa-molybdenum with the composition (NH ₄) ₂[Co(H ₂O) ₄] ₂[Mo ₈O ₂₇]×6H ₂O (I) is synthesized and studied by X-ray diffraction, IR spectroscopy, and thermogravimetry. The compound crystallizes in a triclinic system with the following unit cell parameters: a = 8.62923(9) Å, b = 9.4795(10) Å, c = 12.2071(13) Å, a = 104.326(2)°, b = 109.910(2)°, g = 100.820(2)°, V = 868.18(16) Å ³, ρ _(calc.) = 3.071 g/cm ³, Z = 1. Space group is Р -1. IR spectroscopic and thermogravimetric analyses are performed.

The complex of the composition [Pd ₂(H ₂L ¹)Cl ₄] (I) (H ₂L ¹ is a chiral bis-α-sulfanyl oxime, a derivative of natural monoterpenoid (+)-3-carene) is synthesized. Single crystals of I and solvate [Pd ₂(H ₂L ¹)Cl ₄]×0.5CH ₂Cl ₂ (II) are grown. According to the X-ray crystallographic data, the crystal structure of I consists of acentric molecules of the binuclear [Pd ₂(H ₂L ¹)Cl ₄] complex. The structure of solvate II consists of the molecules of binuclear complex I and CH ₂Cl ₂ molecules. The PdCl ₂NS coordination sites are distorted squares (trapezia). In the structures of I and II, the PdCl ₂ fragments are in the transoid position. In I, the Cl ₂NS planes of the two coordination sites are nearly parallel (the angle between the planes is 7.7(1)°). The similar angle in solvate II is 22.0(1)°.

Conditions are determined for the formation of sodium heteropolyhexamolybdenumnickelate(II) Na ₄[Ni(OH) ₆Мо ₆O ₁₈]·16H ₂O (I) in a Ni(NO ₃) ₂-Na ₂МоO ₄-HNO ₃-H ₂O solution acidified to Z = ν(H ⁺)/ν(МоO ) = 1.00. Synthesized salt I is investigated by chemical analysis, single crystal XRD, powder XRD, thermal analysis, and IR spectroscopy. The heteropolyanion is shown to belong to the Anderson type. Compound I is analyzed by single crystal XRD ( M _r = 1404.61, triclinic, space group P , a = 8.0586(4) Å, b = 10.5445(6) Å, c = 12.1374(5) Å, α= 69.557(5)Å, β = 70.604(4)Å, γ = 84.123(4)Å, V = 911.45(8) Å ³) to find that it is isostructural to Na ₄[Ni(OH) ₆W ₆O ₁₈]·16H ₂O. All metal atoms in the structure of I are in an octahedral environment: the coordination sphere of the Ni heteroatom consists of OH groups; that of Mo consists of O atoms and OH groups; Na atoms are linked to the heteropolyanion via the terminal O atoms of the polyanion and surrounded by water molecules. In the crystal packing, the [Ni(OH) ₆Mo ₆O ₁₈] ^4- anions lie in planes parallel to (1 0) and the polyanion layers alternate with those formed by the paired octahedra [Na ₂(μ-H ₂O) ₂(H ₂O) ₆(O) ₂] in the direction of the y axis.

The synthesis, crystal structures, and characterization (IR, TGA/DSC) of [Nd(C ₅H ₆O ₄)·(H ₂O) ₄]·Cl (1) and Pr(C ₅H ₆O ₄)(C ₅H ₇O ₄)(H ₂O)]·H ₂O (2) are described. Compound 1 is a one-dimensional coordination polymer containing double chains incorporating pairs of edge-sharing NdO ₉ polyhedra linked by glutarate dianions. A network of O-H⋯O and O-H⋯Cl hydrogen bonds helps to consolidate the structure. Compound 2 is a three-dimensional coordination polymer incorporating chains of edge-sharing PrO ₁₀ polyhedra. Its glutarate ion adopts an extended conformation, whereas its hydrogen glutarate ion takes on a twisted conformation. O-H⋯O hydrogen bonds are seen in the crystal structure, which features small channels occupied by water molecules. Crystal data: 1, C ₅H ₁₄ClNdO ₈, M _r = 381.85, monoclinic, P 2 ₁/ c (No. 14), a = 8.9763(6) Å, b = 15.9277(11) Å, c = 8.8690(6) Å, β = 112.090(2)°, V = 1174.94(14) Å ³, Z = 4, R ( F ) = 0.016, wR ( F ²) = 0.037. 2, C ₁₀H ₁₇O ₁₀Pr, M _r = 438.15, orthorhombic, Pbca (No. 61), a = 16.3030(7) Å, b = 8.6714(4) Å, c = 19.3899(8) Å, V = 2741.1(2) Å ³, Z = 8, R ( F ) = 0.020, wR ( F ²) = 0.050.

Two new oxovanadium(V) complexes [VOL ¹(HQ)] (1) and [VOL ²(HQ)] (2) are prepared by the reaction of [VO(acac) ₂] (where acac = acetylacetonate), 8-hydroxyquinoline (HHQ) with 4-bromo- N'-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide (H ₂L ¹) and 2-bromo- N'-(3-ethoxy-2-hydroxybenzylidene)benzohydrazide (H ₂L ²), respectively, in methanol. Crystal and molecular structures of the complexes are determined by elemental analysis, infrared spectroscopy, and single crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P 2 ₁/ c , with unit cell dimensions a = 12.5236(13) Å, b = 22.5260(15) Å, c = 16.7029(13) Å, b = 90.054(2)°, V = 4712.0(7) Å ³, Z = 8, GOOF = 1.024, R ₁ = 0.0586 and wR ₂ = 0.0835. Complex 2 crystallizes in the triclinic space group P -1, with unit cell dimensions a = 7.4344(12) Å, b = 10.8677(16) Å, c = 14.687(2) Å, α = 85.327(5)°, β = 77.357(5)°, γ = 84.896(5)°, V = 1150.9(3) Å ³, Z = 2, GOOF = 1.153, R ₁ = 0.0917 and wR ₂ = 0.3014. The V atoms are in the octahedral coordination. Thermal stability of the complexes is also studied.

Reaction of the morpholine amide derivative of 2-phenyl-4-quinolinecarboxylic acid with mercury(II) acetate and lithium chloride results in chloromercuration at the ortho position on the phenyl ring; the complex was characterised by ESI mass spectrometry and an X-ray structure determination.

The molecular structure of 3-oxo-urs-12-en-28-oic acid anhydride is determined. Crystals of C ₆₀H ₉₀O ₅ compound (III) are monoclinic, space group С2, at 100 K a = 15.1308(13) Å, b = 23.5150(19) Å, c = 15.1275(12) Å, β = 108.276(2)°. Molecules in the crystal are located in a special position on axis 2.

Branched star-like dextran-polyacrylamide copolymers in nonionic and ionic forms are used as matrices for the fabrication of silver nanoparticles. It is demonstrated that due to the features of their molecular structure providing a high local concentration of functional groups, branched polymers stabilize silver nanoparticles more efficiently as compared with their linear analogs. Stable silver colloids are obtained in a branched anionic matrix, meanwhile a linear matrix does not stabilize a nanosystem.

Structures of different classes of organic crystal hydrates are considered and their structural classification is presented based on the dimensionality and planarity of the included (Н ₂О) _n motif (water associate). The structural data are generalized with respect to the proton excess of the water associate.

Quantum chemistry methods are used to analyze in detail the structure of the van der Waals complex of ethylene with oxygen C ₂H ₄-O ₂, and binding energies for stable configurations of the complex are calculated. The calculations are carried out by the MP2 method using the 6-311++G(2 d ,2 p ) and aug-cc-pV n Z ( n = 2, 3, 4) basis sets. It is demonstrated that the most stable structure of the van der Waals complex of ethylene with oxygen is a structure with C _{2 v} symmetry, where the oxygen and ethylene molecules are located parallel and lie in the same plane. The calculation of the binding energy for this structure using the aug-cc-pV n Z ( n = 2, 3, 4) basis sets with the extrapolation of results to the infinite basis set limit ( n → ∞) gives a value of 206 cm ^-1.

A crystallographic analysis of the highly symmetrical cubic structure of Sc _0,8B _9,64C _0,53Si _0,057 is conducted of both centers of the [B ₁₂] and [B ₁₀] cluster groups with Sc and Si atoms and separately all individual atoms. In the first case, the analysis reveals an ordering with an I _cub sublattice ( а ≈ 5.1 Å) and a competing ordering with an F _cub sublattice ( а ≈ 6.8 Å). In the second case (for individual atoms), the analysis reveals orderings with analogous sublattices with twice as small parameters.

Methods of X-ray diffraction analysis and nuclear magnetic resonance are used to determine the molecular structure of macrobicyclic boron-capped tris -dioxymate iron(II) clathrochelate containing an annellated 5-membered heterocycle.

By alternating current electrochemical synthesis a new [Cu ₂( atfmphet ) ₂(CF ₃SO ₃) ₂] π complex is obtained from the alcohol solution of Cu(CF ₃SO ₃) ₂ and 5-(allylthio)-1-[2-(trifluoromethyl)phenyl]-1 H -tetrazole ( atfmphet ) and studied using single crystal X-ray diffraction.

The inclusion compound of the composition [Zn ₂(dmf)(bdc)(lac)]×C ₅H ₆O is obtained by keeping a porous homochiral metal-organic polymer of the composition [Zn ₂(dmf)(bdc)(lac)]·DMF (DMF = N,N-dimethylformamide, H ₂bdc = terephthalic acid, H ₂lac = S -lactic acid) in liquid 2-cyclopentene-1-one, and the crystal structure of the compound is determined.

In this paper, we report the preparation of a four-coordinated copper(I) thiosemicarbazone complex [CuI(PPh ₃)(catsc)] from the reaction of PPh ₃ and catsc (3-phenylpropenalthiosemicarbazone) with CuI. The synthesized complex is characterized by elemental analyses (CHNS) and FT-IR spectroscopy. The crystal structure of [CuI(PPh ₃)(catsc)] is investigated by single crystal X-ray diffraction. The catsc coordinates to the copper(I) ion as a bidentate ligand via the N and S atoms. The complex has a distorted tetrahedral coordination geometry.

A two-dimensional Ni(II) complex {[Ni(BTX)(SDBA)(H ₂O)]·0.29H ₂O} _n (1) (BTX = 1,4-bis(1,2,4-triazol-1-ylmethyl)-benzene, H ₂SDBA = 4,4'-sulfonyldibenzoic acid) is synthesized and characterized using single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. The single crystal X-ray diffraction analysis reveals that complex 1 is a two-dimensional polymer containing 28-membered rings based on the rhomboid subunit [Ni ₂(C ₁₄H ₈O ₆S) ₂] with a Ni-Ni separation of 12.923 Å. The thermal stability and magnetic property of the title complex are briefly investigated.

A one-dimensional Zn(II) complex [Zn(Im) ₂(NO ₂-BDC)] _n (1) (Im = Imdazole, NO ₂-H ₂BDC = 5-nitro-1,3-benzenedicarboxylic acid) is synthesized and characterized using single crystal X-ray diffraction, IR spectroscopy and elemental analysis. Single crystal X-ray diffraction analysis reveals that complex 1 is a one-dimensional chain polymer with a Zn⋯Zn separation of 9.6190(2) Å arranged parallel to the (1 0 0) crystal direction. In addition, the luminescence measurements reveal that complex 1 exhibits strong fluorescent emissions in the solid state at room temperature.

The crystal structures of two N-heterocyclic carbene (NHC)-palladacycles are determined by single crystal X-ray diffraction. The intermolecular C-H⋯Cl hydrogen bonds and π⋯π interactions are found in the crystals.

A method for the synthesis of the Mo(acac) ₃ complex is proposed and its crystal structure is determined by single crystal X-ray diffraction. Space group P 2 ₁/ c , a = 19.7538(5) Å, b = 7.4821(2) Å, c = 34.6190(8) Å, b = 96.8055(12)°, V = 5080.6(2) Å ³, Z = 12. The compound is studied by the thermogravimetric analysis, and MoO ₃ is shown to be the result of its decomposition.

By single crystal X-ray diffraction, the structure of a new compound based on octahedral mixed-ligand anionic cluster complexes of rhenium and cadmium(II) cations is determined: K _0.4Cs _0.6{Cd(H ₂O) ₂Re ₆S ₈(CN) ₄(OH)(H ₂O)}·8H ₂O (1). The compound has a framework structure with a pts (platinum sulfide) topology. The cluster anions are additionally chained together by strong OH…H ₂O hydrogen bonds between the terminal ligands of neighboring clusters; the O…O distance is 2.464 Å.