High-temperature crystal chemistry of normal paraffins with even numbers of carbon atoms

Thermal deformations and phase transformations of evennumbered paraffins C_nH_2n+2(n=20, 22, and 24) have been investigated in a thermal X-ray diffraction study. In homologs with n=20 and 24, phase transformations occur in two steps: triclinic-to-orthorhombic and orthorhombic-to-hexagonal transitions. An orthorhombic rotator phase of even n-paraffins is described for the first time. A crystal-chemical model of the phase transformations of the homologs is suggested. St. Petersburg State University. Translated fromZhurnal Strukturmoi Khimii, Vol. 36, No. 5, pp. 790–798, September–October, 1995. Translated by L. Smolina     

Limits of isomorphous substitution of molecules in normal paraffins as a function of temperature

The limits of isomorphous substitutions and the symmetry of synthetic binary solid solutions of paraffins C_nH_2n+2 with n=17–24 have been studied by X-ray diffraction and thermal X-ray diffraction. Principles of isomorphous substitutions of paraffin molecules are suggested which take into consideration the length (n), the symmetry (parity of n), and the intensity of thermal rotational motion of component molecules.St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii Vol. 34, No. 4, pp. 117–127, July–August, 1993.Translated by T. Yudanova     

Types of rotary crystal state of solid solutions of paraffins

Thermal deformations and polymorphous transformations of solid solutions of paraffins in C₁₇–C₁₉, C₁₉–C₂₁, C₂₁–C₂₃, C₂₂–C₂₄, and C₂₃–C₂₄ systems are investigated by thermal X-ray diffractometry using a temperature step of several tenths of a degree. It is examined how the length of a molecular chain of a homolog (n) and the difference in length (Δn) between the chains as well as the molecular composition of a solid solution affect these transitions, and the data are compared with those for the individual homologs of paraffins. St. Petersburg University. Translated fromZhurnal Struktumoi Khimii, Vol. 39, No. 3, pp. 380–394, May–June, 1998. This work was supported by RFFR grant No. 97-05-65534 and ISSEP grants No. 156p and a97-2633.     

Synthesis and crystal structure of a new molecular complex of fullerene C70, 4BNDY·3C70·4C6H6 (BNDY is binaphtho[1,8-d,e]-1,3-dithiin-2-ylidene)

A new C₇₀-based molecular complex 4BNDY·3C₇₀·4C₆H₆ (1) (BNDY is binaphtho[1,8-d.e]-1,3-dithiin-2-ylidene) was prepared, and its full X-ray diffraction study at room temperature was performed. The C₇₀ molecules in crystal 1 are ordered in different ways, and their ordering depends on van der Waals interactions between them and nonplanar BNDY molecules in the boat conformation. The neighboring BNDY molecules in the structure are bound to each other by π-π interactions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 99–102, January, 2000.     

Volatile mixed-ligand complexes of bis(diisobutyldithiocarbamato)zinc with 1,10-phenanthroline, 2,2′-bipyridyl,and 4,4′-bipyridyl. Crystal and molecular structure of the binuclear complex [Zn2(C10H8N2){(i-C4H9)2NCS2∼4]

Mixed-ligand complexes ZhPhen(i-Bu₂Dtc)₂, Zn(2,2′-Bipy)(i-Bu₂Dtc)₂, and Zn₂(4,4′-Bipy)(i-Bu₂Dtc)₄, where i-Bu₂Dtc=(i-C₄H₉)₂NCS ₂ ⁻ , have been synthesized. The structure of Zn₂(4,4′-Bipy)(i-Bu₂Dtc)₄ was determined by X-ray diffraction analysis; it consists of centrosymmetric binuclear molecules with trigonal-bipyramidal coordination of the central Zn atom. When heated in vacuum, the compounds quantitatively sublimate or evaporate. Thermal decomposition of the compounds in air (350°C) gives α-ZnS. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 6, pp. 1114–1121, November–December, 1996. Translated by L. Smolina     

Synthesis and crystal and molecular structure of mixed-ligand compounds Eu(S2CN(C2H5)2)3(2,2′-Bipy) and Eu(S2CN(C2H5)2)3(1,10-Phen)

Synthetic procedures were developed and X-ray diffraction analysis was performed for two mixed-ligand compounds of europium(III) with diethyldithiocarbamate ions and 2,2′-bipyridyl (2,2′-Bipy) or 1,10-phenanthroline (Phen): Eu(S₂CN(C₂H₅)₂)₃(2,2′-Bipy) (I) and Eu(S₂CN(C₂H₅)₂)₃Phen (II). The structures of the complexes consist of discrete monomer molecules; the coordination polyhedron of Eu (EuN₂S₆ is a node) is a distorted dodecahedron. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 2, pp. 300–309, March–April, 1997.     

Composition and structure refinement of superconducting crystals Y1? x Tb x Ba2Cu3O6+δ ( x = 0.10; δ = 0.75)

Crystals of Y_0.90Tb_0.10Ba₂Cu₃O_6.75 have been prepared by spontaneous crystallization from slowly cooled non-stoichiometric melt of the system Y-Tb-Ba-Cu-O. Average size of platelet crystals having mirror surface is 2×2, the largest — 8×9 mm with thickness 0.1–0.2 mm. The crystals have been characterized by powder X-ray diffraction and electron microprobe analysis. Tetragonal symmetry of the crystals has been determined by X-ray diffraction. Magnetic susceptibility measurements have revealed that the crystals manifest transition to superconducting state without additional annealing (T _c = 60 K). Structures and compositions — Y/Tb ratio (σ = 0.01) and oxygen content (σ = 0.04) — have been refined for two single crystals. Possibility of rhombic distortion of the tetragonal symmetry is discussed. __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 6, pp. 1101–1107, November–December, 2008. Original Russian Text Copyright ? 2008 by L. P. Kozeeva, N. V. Podberezskaya, N. V. Kuratieva, M. Yu. Kamaneva, and A. G. Blinov     

Synthesis, crystal structure, and spectral studies of the molecular complex of [60]fullerene with chloro(triphenylphosphine)gold(I), C60·2[(Ph3P)AuCl]

The molecular complex C₆₀·2[(Ph₃P)AuCl] (1) was synthesized. The crystal and molecular structure of1 was established by X-ray diffraction analysis. At room temperature, the [60]fullerene molecules in complex1 are ordered due to π—π interactions between C₆₀ and the phenyl rings of the chloro(triphenylphosphine)gold(1) molecules. The satellite structure, which accompanies the Cls photoelectron peak of complex1, is indicative of a partial suppression of a channel of losses due to π→π transition in the phenyl ring. The 1R spectral data indicate that either a charge is absent or the charge transfer to the fullerene molecule is negligible. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 365–369, February, 2000.     

Structure reinterpretation and determination of the clathrate nature of the compounds of the general formula MX2·6Py

Unit cell parameters and space group (Ccca) were determined by X-ray diffraction analysis for 11 compounds of the general formula [MPy₄X₂]·2Py (M=Cd, Co, Cu, Ni, Zn; X=Br, I, NO₃, HCOO). It was found that these compounds, together with the five known compounds, form a large group of clathrates, in which [MPy₄X₂) (host) complex molecules are packed with pyridine (guest) molecules held in the voids of the crystal framework by van der Waals forces. The results of the study and literature data are analyzed, and it is concluded that there are at least several dozens more clathrates of the molecular formula MX₂·6Py that are known but not defined structurally. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physical Chemistry, Polish Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 6, pp. 1070–1073, November–December 1995. Translated by L. Smolina     

Synthesis and structure of a product of interaction of acetonitrile with hydrogen bromide, [H2N=C(Me)−NH−C(Me)Br2]Br

A mixture of solid products was obtained upon absorption of dry HBr by MeCN. One of the products, [H₂N=C(Me)−NH−C(Me)Br₂]Br, was isolated as white single crystals and characterized by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2274–2277, November, 1998.     

Crystallographic evidence for intramolecular C−H...O interactions in principal nucleosides. Refinement of the crystal structure of thymidine

An analysis of crystallographic data for the major nucleosides has shown that their molecules (except for guanosine) exhibit specific intramolecular C−H...O interactions, which are weak hydrogen bonds. In purine nucleosides these interactions are rare and rather weak. For pyrimidine nucleosides, in addition to the previously known intramolecular interaction C₆−H₆...O_5′, we have revealed the intramolecular interactions C_1′−H_1′...O₂ and C₆−H₆...O_1′. The three interactions make approximately equal contributions to the stabilization of the anti-conformation in pyrimidine nucleosides and make this conformation prevailing. To enhance the reliability of the results of studying the C−H...O interactions in thymidine, we performed an additional, more exact, X-ray diffraction analysis of the substance. Institute of Physiologically Active Substances, Russian Academy of Sciences, Chernogolovka. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 1, pp. 178–184, January–February, 1995. Translated by I. Izvekova     

Synthesis and structure of layered fluorine-containing crystal hydrates based on aquacomplexes of noble metals

Crystal hydrates were synthesized based on aquaions of noble metals [M(H₂O)₆]F₃·nH₂O, where n = 3–8 and M = Ir, Rh. The structure of the resulting crystal hydrates with three aqueous molecules is characterized by the space group P3, Z = 1 and has a layered form. The positively charged layers [M(H₂O)₆F ₂ ⁺ which alter with negatively charged layers of the composition ∼_-·3H₂O, are located perpendicular to the c axis. According to X-ray structural and nuclear magnetic resonance data, the water molecules and the F_- ions in the negatively charged layers are disordered. Translated fromZhurnal Strukturnoi Khimii, Vol.40, No. 2, pp. 259–264, March–April, 1999.     

Determining the orientations of BrF3 and FeBr3 molecules in graphite fluoride matrices using the XANES and EXAFS polarization dependences

Synchrotron radiation was used to measure the EXAFS and XANES polarization dependences for intercalation compounds of graphite fluoride. An approach is developed which allows one to analyze the orientation of molecules of arbitrary shapes using XANES and EXAFS data. Analyzing the orientation dependences of BrK XANES spectra for the T-shaped BrF₃ molecules, we determined possible combinations and admissible ranges of angles between the normal to the graphite fluoride matrix planes and the Br−F bond directions (α=52–90°, β=27–82°) and between the normal to the matrix planes and the molecular planes (γ=27–53°). The average orientation angles obtained by the combined analysis of the EXAFS and XANES data are as follows: α=62±1.5°, β=58±1.5°, γ=45±1.5°. The interatomic distances Br−F, Br−Br, and Fe−Br are determined. It is established that thermal treatment, which recovers the X-ray diffraction pattern from the unfilled matrix, does not affect the predominant orientation of the BrF₃ molecules. This suggests that the thermally treated graphite fluoride matrix contains thin layers of ordered molecules. The absence of the polarization dependence of the spectra of FeBr₃ in graphite fluoride allows the assumption that the molecular planes are oriented with respect to the normal to the matrix planes at a “magic” angle of 35°. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 6, pp. 1020–1029, November–December, 1995. Translated by I. Izvekova     

Synthesis of mixed-ligand managanese(II) complexes with alkyl xanthate ions and nitrogen-containing heterocycles. Crystal and molecular structure of the [Mn(S2COC3H7−i )2(2,2′-Bipy)] complex

We have synthesized high-spin mixed-ligand Mn²⁺ complexes Mn(S₂COR)₂L where R=i−C₃H₇, i−C₄H₉; [L=1,10-phenanthroline (Phen), 2,2′-bipyridyl (2,2′-Bipy), 4,4′-bipyridyl (4,4′-Bipy)]. As solids, the compounds are stable to oxidation by atmospheric oxygen. An X-ray structural study of the [Mn(S₂COC₃H₇−i)₂(2,2′-Bipy)] complex was carried out. The structure is composed of discrete monomeric molecules. The corrdination polyhedron of the Mn atom is a distorted [4S+2N] octahedron. The molecules are bonded by van der Waals interactions. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 2, pp. 106–111, March–April, 1994. Translated by T. Yudanova     

Synthesis and structure of the complex of 2-(2-pyridyl)-2-oxazoline with PdCl2

The reaction ofN-2-nitroxyethylpicolinamide with PdCl₂ afforded the new complexcis-[2-(2-pyridyl)-2-oxazoline-N,N′]dichloropalladium(u). The structure of this complex was established by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 561–563, March, 2000.     

Force fields of halide-substituted methane derivatives

The paper describes methods for determining the force fields of large sets of molecules which share the common property that in their constituent groups of molecules the equivalent force constants always change monotonically with the properties of substituent atoms belonging to the same subgroup of the periodic table. The force fields of the CH_4−nX_n (n=0–4, X=F, Cl, Br, I) molecules of the methane series are obtained. The applications of these force fields are discussed. In particular, they can serve as a basis for a data bank of the force fields of fragments suitable for constructing the force fields of more complex molecules. Russian Scientific Center “Applied Chemistry”, St. Petersburg. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 2, pp. 250–256, March–April, 1996. Translated by I. Izvekova     

X-ray fluorescent and EXAFS studies of the electronic and spatial structure of dialkyl sulfides and their PdCl2 complexes in extraction systems

SK_α, SK_β, ClK_β, ClK_β, and PdL_β2 X-ray fluorescent and PdK EXAFS spectra were obtained for some organic solutions of dialkyl sulfide complexes with palladium chloride. Solvent effects on the electronic and spatial structure of complexes in solution are discussed. In the benzene solution of [PdCl₂2(C₆H₁₃)₂S], complex molecules interact with solvent molecules along a coordinate that is perpendicular to the plane of the complex molecule. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 4, pp. 105c111, July–August, 1994. Translated by L. Smolina     

Development and study of zeolite catalytic systems for the transformation of lower hydrocarbons into valuable chemicals

The results of studies aimed at the development of highly efficient catalysts based on zeolites of the pentasil family for synthesis of aliphatic and aromatic hydrocarbons from C₂−C₅ olefins and paraffins are summarized. Dedicated to the memory of Academician M. E. Vol'pin timed to his 75th birthday. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1071–1080, June, 1998.     

Water clusters in supramolecular inclusion hydrates. Crystal structure of decaazatricyclo[28.2.2.213.16]tetratriacontane nanohydrate

Inclusion compounds of solvate water molecules in a crystal matrix are investigated by X-ray diffraction analysis of a macrocyclic polyamine decaazatricyclo[28.2.2.2^13.16]tetratriacontane nanohydrate (I). When included in a crystal, water molecules are bonded by water-water (O-H...O) and water—macrocycle (0-H...N and N-H...O) hydrogen bonds, forming a linear cluster. Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 5, pp. 993–1001, September–October, 1999.