Ray Structural Analysis Research Articles

Effect of ligand steric bulk on coordination geometry of pyridine adducts of cadmium(II) carbamodithioates

Pyridine adducts of four different carbodithiolate cadmium compounds [Cd (2–mpipdtc)2(py)] (5); [Cd (4–mpipdtc)2(py)2] (6); [Cd(thqdtc)2(py)] (7) and [Cd(padtc)2(py)2] (8) have been successfully prepared and analysed by using Infrared and nuclear magnetic resonance spectroscopies and single crystal X–ray structural analysis. The N 13CS2 carbon signal for 5 and 6 noticed at 202.7 and 202.9 ppm due to an upfield shift of about 5 ppm matched with that found in 7 (208.2 ppm) and 8 (208.5 ppm). The observed shielding in 5 and 6 expresses the more electron density movement from 2–mpipdtc and 4–mpipdtc to cadmium and closer approach of the 2–mpipdtc & 4–mpipdtc and cadmium. Single crystal X–ray structural analysis showed that the structural patterns of [Cd (2–mpipdtc)2(py)], [Cd (4–mpipdtc)2(py)2], [Cd(thqdtc)2(py)] and [Cd(padtc)2(py)2] compounds are mononuclear distorted trigonal bipyramidal, mononuclear distorted octahedral, dimeric distorted octahedral and mononuclear highly distorted octahedral i.e. trigonal prismatic geometry, respectively. The variation in structure is due to the steric influence of organic substituents of corresponding ligands as well as the size of metal. This point is also supported by bond valence sum analysis.

The influence of ancillary NCS− ions on structural, spectroscopic, magnetic and biological properties of copper(II) l-argininato complex

The anions are one of the factors that govern the self-organization of the crystal structure involving [Cu(l−Arg)]2+ cation complex. Therefore, the crystals of hexa−coordinated l−argininato copper(II) complex with coordinated isothiocyanato ions, trans−[Cu(l−Arg)2(NCS)2]⋅2H2O (1), were synthesized and studied by X−ray structural analysis, spectroscopic techniques (FT−IR, Raman, X− and Q−band EPR, NIR−Vis−UV), magnetic and thermal methods. The distortion of elongated octahedron (T = 0.757) shows the static character. The complex presents a monomeric nature but the [Cu(l−Arg)2(NCS)2] units are bound via O‒H∙∙∙O, N‒H∙∙∙O and N‒H∙∙∙N hydrogen bonds forming two dimensional layers. One broad band with three well−marked maxima at 15,850 cm−1, 16,630 cm−1 and 17,500 cm−1 are generated by 2B1g(dx2-y2) → A1g(dz2), 2B2g(dxy) and 2Eg(dxz ≈ dyz) transitions. The values of g tensor components g⊥=gx=gy 2.056 (77 K) / 2.057 (298 K) agree well with the g⊥ found for other trans−N2O2 chromophore with two chelating l−Arg-ligands in copper(II) xy plane. The relation of gz (g||=2.245) >>gx=gy (g⊥= 2.056) > 2.0023 is characteristic for dx2-y2 orbital of unpaired electron ground state in the axial symmetry of copper(II) environment. The field induced slow magnetic relaxation is observed, despite the lack of the zero-field splitting of Cu(II) monomeric complex 1. Due to the labile character and the preference for distorted coordination geometries leading to plasticity of copper(II) coordination sphere, the comprehensive spectroscopic studies of the complexes arising in aqueous solutions when complex 1 was in aqueous solutions, were conducted (NIR−Vis−UV, EPR). The antimicrobial activity of 1 was evaluated against the yeast, dermatophyte and bacteria. Microsporum gypseum was the most sensitive strain, with a 4-time lower MIC comparing to the reference drug - Fluconazole.

Synthesis and antihypoxic activity of new diphenylguanidine derivatives

Previously undescribed derivatives of diphenylguanidine were obtained, structure and individuality of which have been proven by 1 H, 13 C NMR, IR, X -ray structural analysis, elemental analysis and mass spectrometry. For all compounds, an in vivo study of antihypoxic activity was carried out on a model of acute hemic hypoxia. High antihypoxic activity of 2,5-dioxo- N,N' -diphenylpyrrolidine-1-carboxymidamide was revealed, exceeding the strength of the comparison drug - mexidol.

A nonsymmetric salamo-based turn-off fluorescent probe for the detection of Cu2+ and its structurally rare dinuclear Cu(II) complex

A salamo-based fluorescent probe H2LS was synthesized by grafting 3-tert-butyl-5-bromosalicylaldehyde and 2-hydroxy-1-naphthaldehyde onto 1, 2-bis(aminooxy)ethane. The probe can selectively and sensitively recognize Cu2+ ions, accompanied by a significant fluorescence quenching change from blue fluorescence to no fluorescence, and the probe can rapidly respond to Cu2+ ions in a short time. Meanwhile, there is a linear relationship between the fluorescence intensity at 393 nm and the concentration of Cu2+ ions (0.05–10 mM). Therefore, the probe can realize the quantitative detection of Cu2+ ions in aqueous solutions with a low detection limit of 4.64 × 10−7 M. In addition, X–ray structure analysis of the Cu(II) complex of H2LS showed that one of the two oxime-oxygen atoms of the probe (LS)2− unit is involved in the coordination with Cu(II) atom. The density functional theory (DFT) was validated to further confirm the recognition mechanism of the probe H2LS to Cu2+ ions.

Temperature Dependences of Structural Parameters of PMN in the Region of Diffuse Phase Transition

In this work, we analyzed the structural parameters of the lead magnoniobate sample in the temperature range from 20 ºC to 450 ºC by X- ray structural analysis. It was found that the PMN cubic perovskite cell does not undergo distortions over the entire temperature range under study. In the vicinity of a temperature of 250 ºC in PMN, an abrupt decrease in the coefficient of linear expansion from 1.06∙10-5 K-1 to 0.32∙10-5 K-1, which is possibly associated with a change in the anharmonicity of the potential relief of atoms in the structure, is recorded.

Polarization effect in luminescent mesogenic BF2 complexes derived from heterocyclic benzothiazoles

Two series of benzo(thia)xazoles 1–2 and one series of boron difluoride complexes 2-BF2 derived from benzothiazoles 2 were reported, and their mesomorphic and optical properties were investigated. The crystal and molecular structures of compound 2 and 2-BF2 (all n = 8) were determined by means of X−ray structural analysis, and both crystallize in the triclinic P-1 and monoclinic P21/c. The geometry at boron center is perfectly tetrahedral, and the overall molecular shapes are considered as rod−shape. Both benzo(thia)xazoles 1 and 2 exhibited N or/and SmC phase, and boron complexes 2-BF2 formed N or/and SmC phase. Benzothiazoles 2 showed a much wider temperature range of mesophase than those of benzoxazoles 1, which were attributed to the better polarization by sulfur atom incorporated. Boron complexes 2-BF2 (n = 10, 12) emitted a yellow−to−green emission at λmax = 569–571 nm in CH2Cl2. This is the first mesogenic BF2 complexes derived from benzothiazoles.

X-ray investigation of alloys on the cross sections RGe2–LuGe2 (R – Pr, Nd) and SmGe2–R′Ge2 (R′ – Gd, Tb, Ho, Er, Tm)

The experimental data on ternary R – R ′–Ge systems, where R and R ′ – rare earth metals of cerium or yttrium subgroups, are available in the literature. The investigations were mainly devoted to the sections between digermanides R Ge 2 – R ′Ge 2 . Alloys of the quasi-binary section R Ge 2 –LuGe 2 ( R – Pr, Nd) and SmGe 2 – R ′Ge 2 ( R′ – Gd, Tb, Ho, Er, Tm) annealed at 870 K were investigated by means of X -ray phase and structural analyses, and energy-dispersive X -ray spectroscopy. The alloys for the investigation were synthesized by arc melting of pure metals (purity of the elements higher than 99.9 wt. %) in an arc furnace under argon atmosphere. The alloys were annealed at 870 K in evacuated quartz tubes for 720 h, and subsequently quenched in ice water, and examined by powder X-ray diffraction (DRON-4.07 diffractometer, Fe K α-radiation). The crystal structure of the compounds was refined by the Rietveld method using the program FullProf. The alloys of cross sections R Ge 2 –LuGe 2 ( R – Pr, Nd) contains two phase wth α -ThSi 2 and ZrSi 2 structure types. The alloy Nd 0 . 16 Lu 0 . 18 Ge 0 . 66 contain one phase. The alloys of cross sections SmGe 2 – R ′Ge 2 ( R ′ – Gd, Tb) contain only one phase with α -ThSi 2 structure type. Isostructure ternary phases with the composition Sm 1- x R ′ x Ge 2 (structure type TbGe 2 ), R ′ – Ho, Er, Tm are formed. The polycrystalline samples Pr 0 . 22 Lu 0 . 12 Ge 0 . 66 , Nd 0 . 22 Lu 0 . 12 Ge 0 . 66 , Nd 0 . 19 Lu 0 . 15 Ge 0 . 66 and Sm 0 . 16 Ho 0 . 18 Ge 0 . 66 were investigated by X -ray energy spherical spectroscopy. Keywords : rare-earth metal, X -ray phase analysis, X -ray structure analysis, energy dispersive X -ray spectroscopy, phase equilibria, crystal structure, structure type.

Энергетические затраты при формировании упругонапряженного состояния в слоях ступенчатого метаморфного буфера в гетероструктуре, выращенной на подложке (001) GaAs

AbstractOn the basis of data on X -ray structural analysis performed by the method of reciprocal-space mapping and investigations using secondary-ion mass spectrometry and transmission electron microscopy, it is shown that vertical compressive stresses also arise in a multilayer epitaxial heterostructure comprised of a step-graded metamorphic buffer along with lateral compressive stresses. The cause of the appearance of vertical stresses is the effect of interlayer hardening, which arises due to the deceleration of fragments of glide dislocations by interphase boundaries. Analysis performed within the framework of the linear theory of elasticity shows that the elastically stressed state of the buffer steps is similar to the state that can be achieved as a result of a two-stage deformation process: bulk and biaxial compression. Bulk compression leads to large energy expenditures in the formation of the structure of the buffer steps, which is reflected, in particular, in violation of the coherence between the dislocation-free and the underlying layers.

A noncanonical binding site of chloramphenicol revealed via molecular dynamics simulations

Chloramphenicol, an antibiotic belonging to the family of amphenicols, is an inhibitor of translation. On the basis of X–ray structural analysis of the binding of chloramphenicol to free bacterial ribosomes, the chloramphenicol action mechanism that consists in preventing the binding of aminoacyl-tRNA to the A–site of the large subunit of the ribosome was adopted. However, the known structures of chloramphenicol complexes with bacterial ribosomes poorly explain the results of the experiments on the chemical modification of 23S rRNA, the resistance to chloramphenicol caused by mutations in 23S rRNA and, which is particularly important, the selectivity of chloramphenicol in suppression of translation, depending on the amino acid sequence of the nascent peptide. In the present study the putative structure of the chloramphenicol complex with a bacterial ribosome in the A,A/P,P–state has been obtained by molecular dynamics simulations methods. The proposed structure of the complex allows us to explain the results of biochemical studies of the interaction of chloramphenicol with the bacterial ribosome.

Spontaneous Bicyclometalation of a Single Cobalt(I) Complex Stabilized by a δ‐C–H Agostic Interaction

CoCH3(PMe3)4 is known for a long time for its potential to activate less reactive C–H Bonds under extremely mild conditions by methane elimination. A spontaneous second C–H bond activation at the same center of cobalt complex is not expected. In contrast to previous investigations with certain aryl‐iminophosphane chelating ligands, in this work two consecutive metalation steps at the same complex center lead to a rare example of a cobalt metallabicycle. In the first step a C–H activation results in a five‐membered chelate ring, whereas the second ring is formed by an incomplete C–H activation which stops at a stable, rarely observed δ‐C–H agostic interaction. The results are supported by NMR spectroscopy, X ray structure analysis and density functional theory (DFT) calculations. Knowledge of such agostic interactions are essential in order to understand catalytic reaction paths and studies of such molecular structures of their ring sizes, bite angles and electronic properties have shown that these ligands allow sensitive control within the metal coordination sphere.

Solid state structural investigations of the bis(chalcone) compound with single crystal X-ray crystallography, DFT, gamma-ray spectroscopy and chemical spectroscopy methods

A bis(chalcone), (2E,6E)-2,6-bis((E)-3phenylallidene)cyclohexanone, was characterized by 1H NMR, 13C NMR, FTIR, UV-Vis spectroscopy, gamma-ray spectroscopy and single crystal X- ray structural analysis. The optimized molecular structure of the compound is calculated using DFT/B3LYP with 6-31G (d,p) level. The calculated geometrical parameters are in good agreement with the experimental data obtained from our reported X-ray structure. The powder and single crystal compounds were gama-irradiated using clinical electron linear accelerator and 60Co gamma-ray source, respectively. Spectral studies (1H NMR, 13C NMR, FTIR and UV-Vis) of powder chalcone compound were also investigated before and after irradiation. Depending on the irradiation notable changes were observed in spectral features powder sample. Single crystal X-ray diffraction investigation shows that both unirradiated and irradiated single crystal samples crystallizes in a orthorhombic crystal system in the centrosymmetric space group Pbcn and exhibits an C-H..O intramolecular and intermolecular hydrogen bonds. The crystal packing is stabilised by strong intermolecular bifurcate C-H..O hydrogen bonds and π…π stacking interactions. The asymmetric unit of the title compound contains one-half of a molecule. The other half of the molecule is generated with (1-x,y,-3/2-z) symmetry operator. The molecule is almost planar due to having π conjugated system of chalcones. However, irradiated single crystal compound showed significant changes lattice parameters, crystal volume and density. According to results of gamma-ray spectroscopy, radioactive elements of powder compound which are 123Sb(n,g),124Sb,57Fe(g,p),56Mn, 55Mn(g,n), and 54Mn were determined using photoactivation analysis. However, the most intensive gamma-ray energy signals are 124Sb.

Crystal and Electronic Structures of [5]Radialene Substituted with Quintuple 1,3‐Dithiol‐2‐ylidenes and Its Oxidative Species

AbstractX‐ray structure analysis of the [5]radialene with quintuple 1,3‐benzodithiol‐2‐ylidenes (4) and its tetracation salt, 4 a⋅CS2 and (4 a)4+(ReO4–)4(CH3CN), was successfully carried out. The neutral [5]radialene molecule in 4⋅CS2 adopted a non‐planar structure with an envelope conformation of the central five‐membered ring. In contrast, the central five‐membered ring of 4 a4+ in (4 a)4+(ReO4−)4(CH3CN) adopted a planar structure with significant contribution of an aromatic cyclopentadienide structure. An anion‐π interaction was observed between the ReO4– anion and the central five‐membered ring in (4 a)4+(ReO4–)4(CH3CN). The electronic structures of 4 a and its oxidative species (4 a2+ and 4 a4+) were estimated by density functional theory (DFT) calculations. The optimized structure of 42+ suggested the delocalization of a positive charges over two 1,3‐benzodithiol‐2‐ylidene units through the central five‐membered ring.

Synthesis, crystal structure and magnetic properties of trinuclear chromium(III) basic carboxylate assembly: [Cr3O(salH)7(H2O)2] (salH2=salicylic acid), a new member of [Cr3O] family

Synthesizing a novel trinuclear chromium(III) basic carboxylate complex could give rise to new materials with interesting properties. Complex [Cr3O(salH)7(H2O)2] is formed in a one-pot, self-assembly reaction when the inert reaction mixture is exposed to dioxygen. The structural property of the complex has been acquired by single-crystal X-ray crystallography and further characterized by elemental analysis (EA), infrared (IR), UV–Visible (UV–Vis), fluorescence spectroscopy and thermo gravimetric and differential thermal analysis (TG–DTA). X–ray structural analysis shows a slightly distorted equilateral of the Cr triangle. The most important feature of the title complex is the unusual framework of the [Cr3O] family due to a terminal Ph(OH)CO2- ion of Cr(2) center, which is unique among the structurally characterized (μ3-oxo)-trichromium(III) complexes. Variable-temperature magnetic susceptibility studies indicate that the total spin value of the ground state is 1/2.

Powdered Calcium Hydride Intermetallide TiNi

There was conducted investigation of physical and chemical properties and structural constituents of calcium hydride intermetallide TiNi. There were examined peculiarities of influence of different kinds of consolidation (hot isostatic pressing and hydrostatic pressing with subsequent sintering in vacuum) on chemical and phase composition of compacts from examined powders by means of optical spectrometry and scanning electron micro- scopy, X -ray structural analysis and analysis of gaseous elements. There was established that sintering in vacuum allows decrease content of gaseous oxygen, nitrogen, and particular hydrogen.

STRUCTURE OF "DIMETHYLENETRICYCLOHEXANONE"

The structure of the product of condensation in basic medium of two molecules of formaldehyde with three molecules of cyclohexanone has been proved using X ray structural analysis. Authors: T. I. Akimova, V. V. Nesterov, M. Yu. Antipin, and V. I. Vysotsky. English Translation in Chemistry of Heterocyclic Compounds , 1999, 35 (11), pp 1299-1304 http://link.springer.com/article/10.1007/BF02251997

SYNTHESIS OF DIHYDRO DERIVATIVES OF 2-AMINO-4,5,7-TRIARYLIMIDAZO[1,5- b ]PYRIDAZINE

7-Amino-2,4,5-triaryl-3,4-dihydroimidazo[1,5-b]pyridazines have been synthesized by reacting 4-aryl-1,2-diaminoimidazoles with 1,3-diarylpropenones. The structure of one of the products was confirmed by X ray structural analysis. Authors: N. N. Kolos, V. D. Orlov, B. V. Paponov, and O. V. Shishkin. English Translation in Chemistry of Heterocyclic Compounds , 1999, 35 (10), pp 1207-1213 http://link.springer.com/article/10.1007/BF02323380

Subvalente Galliumtriflate – mögliche Ausgangsverbindungen für Clusterverbindungen des Galliums

AbstractSubvalent Gallium Triflates – Potentially Useful Starting Materials for Gallium Cluster CompoundsBy reaction of GaCp* with trifluormethanesulfonic acid in hexane a mixture of gallium trifluormethanesulfonates (triflates, OTf) is obtained. This mixture reacts readily with lithiumsilanides [Li(thf)3Si(SiMe3)2R] (R = Me, SiMe3) to afford the cluster compounds [Ga6{Si(SiMe3)Me}6], [Ga2{Si(SiMe3)3}4] and [Ga10{Si(SiMe3)3}6]. By crystallization from various solvents the gallium triflates [Ga(OTf)3(thf)3], [HGa(OTf)(thf)4]+ [Ga(OTf)4(thf)3]−, [Cp*GaGa(OTf)2]2 and [Ga(toluene)2]+ [Ga5(OTf)6(Cp*)2]− were isolated and characterized by single crystal X ray structure analysis.

Design of optical pickups by combining structural analysis and ray tracing

Recently, the demand for slim optical pickups has been increasing due to the expansion of the laptop PC market. As the optical pickups get thinner, they become less rigid, and the quality of the readout signals deteriorates due to thermal deformation. We developed a method to design an optical pickup with high reliability even under harsh conditions by using a combination of ray tracing and structural analysis. We applied this method to design a current DVD slim pickup, and achieved quality equal to that of half-height pickups.

Synthesis and X-ray crystal structure of 3-cyclopentadienyl- 9-(acetomercuro)-3-cobalta-1,2-dicarba-closo-dodecaborane

Electrophilic mercuration of 3-η 5 -cyclopentadienyl-1,2-dicarba-3-cobalta-closo-dodecaborane 1 with (AcO)2Hg in CH2Cl2/AcOH (7:1) leads mainly to 9-acetomercuro-cobaltacarborane 2. In addition, 8-mono- and 9,12-dimercurated products 3 and 4 were isolated in small yields. The X- Ray structural analysis of 2 reveals the Hg-B bond length of 2.10(1) A.

The Causes of Structural Aging of Asphalt

The structure of asphalt, whose colloidal structure is determined by the spin dipole properties of the compounds it contains, is examined. The possibility of constructing models of associates of petroleum systems is evaluated. It is shown that associative combinations of asphalts have a central—spherical structure with two characteristic kinds of nuclei. The possible appearance of a graphite—like stack structure in asphalt with an amorphous paramagnetic nucleus, detected by not only x—ray structural analysis but also by electron paramagnetic resonance, is substantiated.