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Journal of Structural Chemistry

2008 year, number 5

1.
Electronic structure and magnetic properties of double perovskites Sr2FeMO6 (M = Sc, Ti, , Ni, Cu) according to the data of FLAPW-GGA band structure calculations

V. V. Bannikov, I. R. Shein, V. L. Kozhevnikov, A. L. Ivanovskii
Keywords: double perovskites Sr2FeMO6, band structure, magnetism, modeling
Pages: 815-820

Abstract >>
Changes in the electronic structure and magnetic characteristics of Sr2FeMO6 double perovskites were studied by the FLAPW-GGA ab initio band structure method in relation to the type of the cation M = Sc, Ti, , Ni, Cu.



2.
ELECTRONIC ENERGY STRUCTURE OF MBiS2 (M = Li, Na, K) CALCULATED WITH ALLOWANCE FOR THE DIFFERENCE BETWEEN THE M-S and Bi-S bond lengths

B. V. Gabrel'yan, A. A. Lavrentiev, I. Y. Nikiforov, V. V. Sobolev
Keywords: electronic structure, sulfides, density of electronic states, X-ray spectra
Pages: 821-826

Abstract >>
The modified augmented plane wave method (WIEN2k program) was used to study the electronic energy structure and calculate the SK-absorption spectra of LiBiS2, NaBiS2, and KBiS2. The crystal structures of the compounds were modeled using symmetric structures, in which each sulfur atom was surrounded by three alkali metal atoms and three bismuth atoms in such a way that the alkali metal-sulfur and bismuth-sulfur bond length differed. This difference between bond lengths was calculated from the sum of the ionic radii of the components of compounds and by the geometry optimization of the crystal lattice. The two variants of calculation allowed us to check the applicability of Pauling's idea about preservation of the bond lengths of elements in compounds for modeling the crystal structures of LiBiS2, NaBiS2, and KBiS2. The SK absorption spectra and optically forbidden bands were calculated.



3.
Electronic structure and chemical bond in carbides crystallizing in the Fe-W-C system

A. V. Ilyasov, A. A. Ryzhkin, V. V. Ilyasov
Keywords: electronic energy structure, chemical bonding
Pages: 827-834

Abstract >>
The electronic energy structure of MC, M6C, and M12C carbide systems and iron martensite in the absence of spin polarization was studied by the local coherent potential method using the cluster version of the approximation in terms of multiple scattering theory. The local partial density of the electronic states of atoms in crystals was calculated and their electronic structures were compared. The peculiarities of chemical bonding in crystals are discussed.



4.
QUANTUM-CHEMICAL STUDY OF THE ROLE OF CONICAL INTERSECTIONS IN PHOTOISOMERIZATION PROCESSES OF the [RuCl5NO]2- COMPLEX

V. I. Baranovskii, O. V. Sizova
Keywords: transition metal nitroso complexes, bond isomers, conical intersections, quantum-chemical calculation, density functional method
Pages: 835-841

Abstract >>
The potential surfaces of the ground and lowest excited states of the [RuCl5NO]2- complex ion were studied by density functional theory. The conical intersections between the potential surfaces of the ground and lowest excited states were found and characterized. The possible routes from the conical intersection points to the ground state and metastable bond isomers were traced. A preliminary scheme, describing photoisomerizations in the complex, was suggested.



5.
Quantum-chemical study of the structure of COPPER(i) acetate and trifluoroacetate oligomers

Z. G. Bazhanova, Y. I. Tarasov, D. M. Kovtun, A. I. Boltalin, B. K. Novosadov, I. V. Kochikov
Keywords: copper(I) acetate, copper(I) trifluoroacetate, quantum-chemical calculations, oligomers, structure
Pages: 842-850

Abstract >>
The results of B3LYP quantum-chemical calculations of the equilibrium structures of [(CX3COOCu)2]3, [(CX3COOCu)2]2, and (CX3COOCu)2 oligomers (X = H, F) using the cc-pVTZ correlation-consistent basis for C, O, and F atoms and the Stuttgart 1997 RSC basis and relativistic effective core potential for Cu(I) atoms are presented. The differences in the structures of the free dimer and dimer units in oligomers. The hexamer structure was chosen as the model of a fragment of the crystalline phase. Good agreement was obtained between the experimental and calculated differences between the geometrical parameters of the structures in the "gas phase−crystal" and "acetate−trifluoroacetate" series. Based on the calculated data, the increase in the Cu(I)-Cu(I) bond length in the silver acetate crystal compared with the gas phase can be explained by the effect of the neighboring dimer units of the polymer ribbon and the increase in the Cu(I)-Cu(I) bond length in gaseous trifluoroacetate compared with acetate, by the acceptor effect of fluorine atoms.



6.
Camphor-based α-Bromoketones for the Asymmetric Darzens Reaction: Insights into the Mechanism Using Density Functional Theory

J.Y. Yuan1, X.C. Liao2, H.M. Wang3, M.S. Tang4
1 Center of Computational Chemistry, Department of Chemistry, Zhengzhou University, hmwang06@163.com
2 Center of Computational Chemistry, Department of Chemistry, Zhengzhou University, hmwang06@163.com
3 Center of Computational Chemistry, Department of Chemistry, Zhengzhou University, hmwang06@163.com
4 Center of Computational Chemistry, Department of Chemistry, Zhengzhou University, hmwang06@163.com
Keywords: DFT, Darzens condensation, benzaldehyde, acetaldehyde, endo-2-bromoacetylisoborneol, mechanism, transition states, diastereoselectivity, aldol, boat-like, chair-like
Pages: 851-860

Abstract >>
Density functional theory (DFT) calculations at B3LYP/6-31G(d,p) level were carried out to investigate the mechanism of the reaction of benzaldehyde (BA) or acetaldehyde (AD) with (1R)-2-endo-bromoacetyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol (endo-2-bromoacetylisoborneol) 1 (Scheme 1). The calculations indicate that the reactions are diastereoselective, in good agreement with the experimental results [1]. Moreover, the calculations show that these reactions proceed via two steps: (1) an aldol-like reaction and (2) the formation of an epoxide. Our calculation study of the transition states demonstrate that the terminal hydroxyl group in compound 1 is vital to the stereoselectivity of the reactions.



7.
Quantum-chemical study of germanium−substituent bonds in tricoordinated germanium compounds

N. V. Alekseev, E. A. Chernyshev
Keywords: quantum chemistry, NBO method, AIM method, tricoordinated germanium compounds
Pages: 861-870

Abstract >>
The spatial and electronic structures of molecules with three substituents at the germanium atom (tricoordinated germanium) were calculated by the DFT method (Gaussian-98 program package, B3LYP functional, 6-311G(d,p) basis set). The main characteristics of Ge-X bonds in thee molecules were determined by NBO and AIM procedures. It is shown that Ge-X are weak, "intermediate" type bonds. The bond energies were calculated.



8.
MOLECULAR STRUCTURE OF NICKEL(II) AND COPPER(II) N,N′-ETHYLENE-BIS(ACETYLACETONEIMINATES) MO2N2C12H18 AcCORDING TO GAS-PHASE ELECTRON DIFFRACTION DATA AND QUANTUM-CHEMICAL CALCULATIONS

G. V. Girichev, N. I. Giricheva, N. P. Kuzmina, Y. S. Medvedeva, A. Y. Rogachev
Keywords: structure, Schiff bases, CuO2N2C12H18, NiO2N2C12H18, Cu(acacen), Ni(acacen), electron diffraction, quantum-chemical calculations
Pages: 871-882

Abstract >>
The molecular structure of nickel(II) and copper(II) N,N′-ethylene-bis(acetylacetoneiminates), NiO2N2C12H18 and CuO2N2C12H18, at 442(5) K and 425(5) K, respectively. Both molecules have 2 symmetry with a nearly planar MN2O2 coordination site and internuclear distances rh1(M-O) = 1.862(10)/1.923(17) and rh1(M-N) = 1.879(10)/1.947(18) for Ni(acacen) and Cu(acacen), respectively. The structure of free molecules is close to the structure of molecules in crystal. The DFT/3LYP quantum-chemical calculations (CEP-31G and 6-31G* basis sets) gave a molecular structure that agreed satisfactorily with the one found in experiment. The low-spin 1 and high-spin 3 states of the Ni(acacen) molecule were considered. It was found that a change in multiplicity caused significant changes in the geometrical and electronic structure of the MN2O2 coordination site. As shown by experiment and calculations for the NiO2N2C12H18 molecule, the low-spin 1 state is the ground state. The internal rotation of CH3(CN) and CH3(CO) methyl groups was studied by the 3LYP/CEP-31G method. It was shown that steric hindrances led to a high rotation barrier of the CH3(CN) group.



9.
electron diffraction and quantum-chemical study of the molecular structure of 2-chlorobenzenesulfonyl chloride

V. N. Petrova, V. M. Petrov, G. V. Girichev, H. Oberhammer, S. N. Ivanov
Keywords: 2-chlorobenzenesulfonyl chloride, conformer, molecular structure, internal rotation, potential functions, gas-phase electron diffraction, quantum chemistry, mass spectrometry
Pages: 883-890

Abstract >>
The molecular structure of 2-chlorobenzenesulfonyl chloride was studied by electron diffraction and quantum-chemical (2/6-31G**, B3LYP/6-311++G**) methods at 337(3) K. Only one (C1) conformer was found in the gas phase. The following structural parameters were obtained: rh1(C-H)av = 1.105(6) , rh1(C-C)av = 1.398(3) , rh1(C-S) = 1.783(11) , rh1(S=O)av = 1.427(3) , rh1(S-Cl) = 2.048(4) , rh1(-Cl) = 1.731(9) , ∠(-S=O1) = 109.9(8), ∠(-S=O2) = 106.9(8), ∠(Cl1-S-O1) = 107.3(4), ∠(Cl1-S-O2) = 106.4(4), ∠C-S-Cl = 102.1(6), ∠O=S=O = 122.3(11). The C2-C1-S-Cl1 torsion angle that defines the position of the S-Cl bond relative to the plane of the benzene ring was 69.7(8). The B3LYP/6-311++G** calculated barriers of internal rotation of the sulfonyl chloride group were V01 = 9.7 kcal/mol and V02 = 3.6 kcal/mol.



10.
epr study of the nature of the impurity centers responsible for the scintillation proeprties of the Li2Zn2(MoO4)3 crystal

V. A. Nadolinnyi, N. V. Chernei, A. V. Sinitsyn, A. A. Pavlyuk, S. F. Solodovnikov
Keywords: EPR, X-ray analysis, scintillator, copper ions, EPR spectrum modeling
Pages: 891-895

Abstract >>
The binary molybdate Li2Zn2(MoO4)3 of a new crystal type was characterized by EPR, optical spectroscopy, and X-ray diffraction methods. The crystals have the Pnma symmetry group and the lattice parameters = 5.1139(5) , b = 10.4926(13) , c = 17.6445(22) ; Z = 4. The crystals possess scintillation properties; emission is caused by the presence of impurity levels in the forbidden band. The EPR studies of the nature of the impurity centers responsible for the scintillation characteristics of the crystal showed that the centers were Cu2+ ions substituted for zinc ions in the oxygen octahedra. The directions of the main values of the g and tensors (gzz, Azz) correspond to the direction of O-Cu-O of the oxygen octahedron distorted along the Z axis. The EPR spectra of the copper ions are described by the spin Hamiltonian with the parameters g|| = 2.38, g = 2.06; A|| = 116 G, = 0 G.



11.
ANGULAR INVARIANTS and local order in the structures of substances

D. L. Tytik
Keywords: crystal module, Delaunay partitioning
Pages: 896-900

Abstract >>
A method is suggested for analyzing the model structures of crystals by calculating the spherical coordinates of the normals to the simplex faces of the simplicial Delaunay partitioning of a set of points (atoms). The normals to the simplex faces of the Delaunay partitioning of the crystal structure characterize the structure at the local level. An algorithm for constructing the invariant of the crystal structure (crystal module) was considered. Crystals modules were constructed for hexagonal and cubic ices.



12.
structure modification in crystallizations according to molecular dynamic simulations of NaCl CLUSTERS

Y. G. Bushuev, S. V. Davletbaeva
Keywords: structure of metastable liquids, nucleation, nucleation kinetics, crystallization, computer simulation of liquids
Pages: 901-906

Abstract >>
A simulation of crystallization and a structural study of an overcooled NaCl melt are reported. A criterion is suggested for classifying the structural states of ions in the transition mode of nucleation. It is shown that in the bulk of overcooled liquid, short-lived crystal phase germs appear and vanish. A distribution of the critical clusters according to form and size was found. It was assumed that crystal growth occurred by collective synchronization of particle motions in crystal and liquid near the interface. The NaCl nanocrystals formed during nucleation are cubic crystals with clear-cut faces and edges. Overcooling the liquid to a greater extent led to the formation of defective polycrystalline structures.



13.
Dielectric properties of a liquid of dipole hard spheres

G. B. Litinskii
Keywords: Kirkwood factor, dielectric permittivity, polar liquids, dipole hard spheres
Pages: 907-911

Abstract >>
The Kirkwood factor gK of a model polar liquid of dipolar hard spheres (DHSs) was approximated by analytical equations using the approximation of the interaction of the second neighbors within the hindered rotation model. The derived equations describe the temperature and density dependences of the dielectric functions of the DHS liquid.



14.
Solvation of magnesium chloride and sulfate in aqueous solutions at 278.15-323.15 K

V. N. ??fanasiev, A. N. Ustinov
Keywords: hydration number, compressibility of hydration complexes
Pages: 912-919

Abstract >>
Isoentropy compressibilities of aqueous magnesium chloride and sulfate were determined based on precision measurements of ultrasound velocity, density, and isobaric heat capacity at low to high concentrations at 278.15-323.15 K. The hydration numbers h and the molar parameters of volume and compressibility were calculated based on thermodynamically correct equations for hydration complexes (Vh, βhVh), water in the hydration shell (V1h, β1hV1h), and the void containing a stoichiometric mixture of ions (V2h, β2hV2h). The h and βhVh values were found to be independent of the temperature; the molar compressibility of the hydration sphere (β1hV1h) and the stoichiometric mixture of ions without a hydration shell (β2hV2h) were independent of the concentration under the stated conditions. The effect of the electrostatic field of ions on the temperature dependence of the molar volume of water in the hydration sphere was more significant than the effect of pressure on the temperature dependence of the molar volume of bulk water. This is attributed to changes in the dielectric constant of water in the vicinity of the electrolyte ions.



15.
Thermodynamic analysis of the dynamic structure of micellar solutions of sodium alkyl sulfates

Y. A. Mirgorod
Keywords: sodium alkylsulfates, micelle, thermodynamic cycles, hydrophobic interaction, bistable structure
Pages: 920-925

Abstract >>
The results of previous studies of the increments ΔG0CH2, ΔH0CH2, TΔS0CH2 and in hydrocarbon solution processes in water, evaporation, hydration, and transfer from vapor and water to surfactant micelles are summarized. The corresponding thermodynamic cycles were constructed. A micelle was shown to be a bistable structure formed by the contact and water-separated hydrophobic interactions of the alkyl groups of surfactants. The fraction in ΔG0CH2M is -2.3 kJ⋅mol-1 for the contact associate and -0.7 kJ⋅mol-1 for the hydrated one. Water is involved in the hydrophobic interaction of each associate. In a dualist micelle, however, ΔG0CH2 = -3.0 kJ⋅mol-1 equals that of the dispersion interaction after condensation from vapor. The dual nature of the dynamic properties of micelles is discussed.



16.
X-ray and conformation analysis of the new trinuclear cluster of osmoim Os3(μ,η2-OCC6H5)(η3-C3H5)(CO)9

V. A. Maksakov, N. V. P??rvukhina, N. V. Podberezskaya, M. Y. Afonin, V. A. Potemkin, V. P. Kirin
Keywords: triosmium carbonyl clusters, synthesis, crystal structure, conformation analysis
Pages: 926-932

Abstract >>
The crystal structure of the Os3(μ,η2-O=CC6H5)(η3-C3H5)(CO)9 cluster synthesized by the reaction of the (μ-H)Os3(μ-O=CC6H5)(CO)10 complex with allylamine in chloroform was determined by X-ray analysis. Prolonged storage of the reaction mixture led to N-C bond cleavage in allylamine and η3-addition of the allyl fragment at one of the Os atoms (Os-C 2.246 , 2.248 , and 2.273 ). The unit cell parameters of the complex are a = 9.494(1) , b = 10.479(1) , c = 12.474(2) , α = 84.55(1), β = 70.08(1), γ =
70.72(1), V = 1255.8(4) 3, space group Z = 2; C19H10O10Os3; dcalc = 2.922 g/cm3, 3085 Ihkl > 2σI of 3611 collected reflections; R = 0.0252. The structure of Os3(μ,η2-O=CC6H5)(η3-C3H5)(CO)9 is molecular. The plane of the Os3 triangle and the OsCOOs plane are connected according to the "butterfly" principle with an angle of 103.4 between them. The Os-Os distances in the cluster core vary from 2.836(1) to 2.844(1) ; the Os-Ccarb distances are 1.88(1)-1.97(1) ; the distances to the atoms of the bridging ligands are Os-C 2.11(1), Os-O 2.14(1) ; the O-C bridging bond is 1.24(1) . The conformations of the Os3(μ,η2-O=CC6H5)(η3-C3H5)(CO)9 triosmium cluster were studied theoretically. The potential curve of the internal rotation of the allyl ligand relative to the Os(1)-(9) bond was determined. The rotation barrier of the allyl ligand in crystal relative to the Os(1)-(9) bond is 8.38 kJ/mol, and the rotation of the ligand is not hindered. The effects of the intra- and intermolecular interactions on the conformation state of the cluster complex is considered.



17.
X-ray and quantum-topological studies of intermolecular interactions in partially fluorinated quinoline crystals

I. Y. Bagryanskaya, M. A. Grishina, L. Y. Safina, G. A. Selivanova, V. A. Potemkin, Y. V. Gatilov
Keywords: X-ray analysis, quantum-topological analysis, fluorinated quinolines, supramolecular motifs, π-stacking, NH, FH, FF, and C-Fπ nonvalent interactions
Pages: 933-941

Abstract >>
An X-ray study of the crystals of bicyclic compounds containing fluorinated aromatic and nonfluorinated heteroaromatic rings, 5,6,7,8-tetrafluoroquinoline, 5,6,8-trifluoroquinoline, 5,7-difluoroquinoline, 5,7,8-trifluoro-2-phenylquinoline, and 5,7,8-trifluoro-6-trifluoromethylquinoline, was carried out. The basic supramolecular motifs and the underlying intermolecular interactions that control the lattice structure of these compounds were investigated. B3LYP DFT quantum-chemical calculations (6-311G(d,p) basis set) and the topological analysis of the electron density distribution in terms of Bader's QTAIM theory were performed for the compounds. It is shown that the intermolecular interactions in question, traditionally regarded as nonvalent interactions, are related, to a definite extent, to the formation of very weak covalent chemical bonds in the intermolecular space due to the overlap of the "tails" of the molecular wave functions.



18.
SEVERAL ASPECTS OF INTERMOLECULAR INTERACTIONS BETWEEN THE CARBONYL AND IMINE GROUPS IN THE CRYSTALS OF COMPOUNDS CONTAINING SIX-MEMBERED HETEROCYCLES

N. I. Golovina, G. N. Nechiporenko, I. N. Zyuzin, D. B. Lempert, G. G. Nemtsev, G. V. Shilov, A. N. Utenyshev, K. V. Bozhenko
Keywords: X-ray analysis, intermolecular interactions, quantum-chemical calculations, 1, 3, 5-trihydro- xyisocyanuric acid dihydrate, 4-aminouracil, 4-aminouracil monohydrate
Pages: 942-949

Abstract >>
Three modifier compounds that stabilize the phase state of ammonium nitrate over a wide range of temperatures, 1,3,5-trihydroxyisocyanuric acid dihydrate (1), 4-aminouracil (2), and 4-aminouracil monohydrate (3) were studied by X-ray diffraction. Strong donor-acceptor intermolecular interactions were found for structures 2 and 3. The electronic parameters of the molecules were calculated by quantum-chemical methods, and it was found that additional intermolecular interactions were possible.



19.
rystal and molecular structures of (3Z)-()-4-(2′-hydroxypropyl)amino- and (3Z)-4-(2′-hydroxyethyl)aminopent-3-en-2-ones

A. B. Dobrynin, P. I. Gryaznov, O. E. Naumova, I. A. Litvinov, V. A. Alfonsov
Keywords: 4-(2?-hydroxyalkyl)amino-pent-3-en-2-ones, crystal and molecular structures, X-ray diffraction analysis
Pages: 950-955

Abstract >>
An X-ray study of (3Z)-()-4-(2′-hydroxypropyl)amino- and (3Z)-4-(2′-hydroxyethyl)aminopent-3-en-2-ones is reported. The bond lengths inside the H ring are equalized due to the classical N-HO hydrogen bond between the carbonyl oxygen and the amino group. In the 4-(2′-hydroxyethyl)aminopent-3-en-2-one crystal, due to the classical N-HO bonds, infinite zigzag chains are formed along the 0b axis and arranged into a layered structure due to the weak C-HO interactions. In ()-4-(2′-hydroxypropyl)amino-pent-3-en-2-one crystal, however, centrosymmetric dimers are formed, which are then linked by weak
C-HO intermolecular interactions, which form a layered structure along the a0b plane.



20.
Theoretical studies on the structure and spectroscopic properties of pseudohalides

N.B. Okulik1, A.H. Jubert2, E.A. Castro3
1 Facultad de Agroindustrias, Universidad Nacional del Nordeste
2 Programa CEQUINOR, Departamento de Quimica, Facultad de Ciencias Exactas, UNLP
3 INIFTA (CCT-LP, CONICET-UNLP), Divisin Qumica Terica, Departamento de Qumica, Facultad de Ciencias Exactas, UNLP
Keywords: pseudohalides, photoelectron spectroscopy, theoretical calculations, DFT, ab initio methods
Pages: 956-970

Abstract >>
Pseudohalogen-containing compounds have attracted significant interest among nonmetal chemists and theorists, not only owing to their potential use in various fields but also due to difficulties in their experimental preparation and characterization. Since its introduction in 1925, the pseudohalide principle has been used extensively and, therefore, a remarkable progress has been made in the experimental and theoretical research on the compounds of this kind. In this work, we review studies on structural investigations and theoretical characterizations of several pseudohalide-containing compounds in order to contribute to better understanding of the chemistry of many such species.



21.
Conformational Features of Cl3P=NC(CF3)3 and Cl3P=NCCl(CCl3)2 Molecules According to Results of Non-empirical calculations

S. N. Shurov, G. B. Soifer
Keywords: trichlorophosphazene compounds, non-empirical quantum chemical calculations, molecular geometry of conformers
Pages: 971-973

Abstract >>
Non-empirical RHF/6-31G* and MP2/6-31G* quantum chemical methods are used to calculate the molecular structure of trichlorophosphazene compounds: Cl3P=NC(CF3)3 (I) and Cl3P=NCCl(CCl3)2 (II). The corresponding geometric parameters obtained from the calculations are compared with X-ray diffraction analysis data reported in the literature. Conformational differences between the molecules of I and II, previously found by X-ray diffraction in the crystals of these compounds, are confirmed by non-empirical calculations of the molecules in the free state. The features of their geometry caused by intramolecular interactions are discussed.



22.
General formula to calculate formal unsaturation of chemical compounds

Y. I. Morozik, P. V. Fomenko, A. V. Shantrokha
Keywords: identification of unknown compounds, formal unsaturation, graph theory
Pages: 974-976

Abstract >>
Based on graph theory fundamentals, a general formula to calculate formal unsaturation of chemical compounds that contain atoms of any valence is deduced and the mathematical meaning of this widely used chemical concept is shown.



23.
Equation of state of the hard sphere liquid

Y. T. Pavlyukhin
Keywords: hard sphere liquid, equation of state of the hard sphere liquid
Pages: 977-981

Abstract >>
Using the results of Monte Carlo simulation, equations of state of hard sphere liquids are calculated for 106 values of the fill factor η = 0.005-0.530 (step of 0.005). In the region of liquid phase stability the absolute accuracy of about 0.00001-0.00008 is reached. Correctness of the accuracy estimate is discussed. The results obtained are compared with reported equations of state of the hard sphere liquid.



24.
X-ray diffraction experiment on DyBr3:20H2O, YbBr3:20H2O solutions. Pre-main peak as a prerequisite to consider the structural organization of solutions

O. V. Grechin, V. V. Kuznetsov, M. V. Yakimova
Keywords: aqueous solutions, lanthanide cations, X-ray diffraction method, pre-main peak (PMP), diffusion-averaged structure (D-structure), cation coordination environment, simulation of solutions
Pages: 982-984

Abstract >>
Primary data of the X-ray diffraction experiment on DyBr3 and YbBr3 aqueous solutions in salt:water molar ratios of 1:20 are presented. The occurrence of a pre-main peak in the curves of normalized scattering intensities determines the average distance between cations in these solutions, and hence, directs to a model description of the structure of solutions. Based on the determination of boundaries of the cation complex and taking into account the deficit of solvent, the model of the cation complex is supposed to consist of two coordination shells involving at least two anions.



25.
Refinement of LiFe5O8 crystal structure

A. I. Smolentsev, . B. Meshalkin, N. V. Podberezskaya, . B. Kaplun
Keywords: lithium and iron oxides, lithium ferrite, vibrational phase analysis (VPA), spinel structure type, structure refinement
Pages: 985-988

Abstract >>
The crystal structure and the formation conditions of crystals of the LiFe5O8 ordered phase obtained from the solution-melt of the Bi2O3-Fe2O3-B2O3-LiCl quadruple system are refined. The crystals are black, octahedral, of cubic symmetry (space group P4332). Unit cell parameters: a = 8.3339(1) , V = 578.82(1) 3, Z = 4, dcalc = 4.753 g/cm3. From 6046 of the collected array Ihkl 358 are independent (Rint = 0.0321). As a result of anisotropic refinement of structural parameters, R1 factor is found to be 0.0186 (wR2 = 0.0467). Lithium atoms are in octahedral environment, Li-O is 2.109(1) ; iron atoms are of two types: in octahedra with Fe-O (by two) distances of 1.9586(9) , 2.0152(9) , and 2.0652(10) and tetrahedra with Fe-O (three) 1.8848(10) and 1.914(2) . The structure is of inverted spinel type.



26.
Crystal structure of trans-bis(trifluoro-acetylacetonato)copper(II)

I. A. Baidina, P. A. Stabnikov, S. A. Gromilov, A. I. Smolentsev
Keywords: copper, β-diketonates, single crystal X-ray diffraction, crystal chemistry
Pages: 989-992

Abstract >>
Triclinic modification of trans-bis(trifluoroacetylacetonato)copper(II) has been studied by single crystal X-ray diffraction (diffractometer X8 APEX BRUKER, MoKα radiation, T = 173(2) K). The structure is molecular. Square environment of the Cu atom (u-Oav 1.916 , ∠O-u-Oav 93.4) is completed to a bi-pyramid by two γ atoms of neighboring molecules, Cuγ 3.18 and 3.23 .



27.
Crystal structure of acrylamide

A. A. Udovenko, L. G. Kolzunova
Keywords: acrylamide, crystal structure, bond lengths, bond angles
Pages: 993-996

Abstract >>
Crystal structure of acrylamide has been re-determined by single crystal X-ray diffraction (133(1) K, BRUKER SMART 1000 CCD, a = 8.228(1) , b = 5.759(1) , c = 9.760(1) , β = 120.04(1), V =
400.3(1) 3, space group P21/c, Z = 4, R = 0.0543 for 867 reflections). In the structure strong hydrogen bonds N-HO join the molecules of C3H5NO into bi-molecular layers, which make CC molecular contacts. It has been demonstrated that the process of sold phase polymerization of acrylamide should proceed through the cleavage of double bonds (1)=(2) in the monomers and formation of bonds (1)-(1) and (2)-(2) between the closest carbon atoms of different layers.



28.
X-ray structural investigation of 1,3,6-trichloro-3,6-dimethylcycloheptanecarbonitrile and 2,5-dimethyl-2,5-dichlorohexane - the products of reaction of 2,5-dimethyl-1,5- hexadiene with trichloroacetonitrile

A. A. Karapetyan, R. A. Tamazyan, A. R. Mikaelyan, A. M. Grigoryan, A. S. Vardanyan, L. Z. Nikogosyan
Keywords: regio- and stereospecific intramolecular cyclization, cycloheptanecarbonitrile
Pages: 997-1000

Abstract >>
Addition of trichloroacetonitrile to 2,5-dimethyl-1,5-hexadiene in presence of cuprous amine complexes has been studied. Single crystal X-ray diffraction unambiguously proves that the main product is a racemic mixture of the cyclic symmetric nitrile - (1r,3R,6S)- and (1r,3S,6R)-1,3,6-trichloro-3,6-dimethylcycloheptanecarbonitrile. Established relative configuration of the product confirms the ring closure mechanism suggested before. Also, a side product - 2,5-dimethyl-2,5-dichlorohexane has been isolated (the product of hydrochlorination of the starting alkadiene). Low-temperature (190 K) structural examination of this centrosymmetrical molecule indicates that the unit cell comprises one molecule.



29.
Crystal and Molecular Structure of ()-2-[(1S,3S)-3-Acetyl-2,2-Dimethylcyclobutyl]-N-(p-Tolyl)Acetamide

Y.-B. Yin1, Z.-Q. Song2, Z.-D. Wang3, H.-Q. Jiang4
1 Institute of Chemical Industry of Forest Products Chinese Academy of Forestry, songzq@hotmail.com
2 Institute of Chemical Industry of Forest Products Chinese Academy of Forestry, songzq@hotmail.com
3 College of Forestry, Jiangxi Agricultural University, songzq@hotmail.com
4 Institute of Chemical Industry of Forest Products Chinese Academy of Forestry, songzq@hotmail.com
Keywords: single crystal X-ray diffraction, crystal structure, terpenes, pinonic acid, cyclobutane fragment, hydrogen bond
Pages: 1001-1004

Abstract >>
The structure of ()-2-[(1S,3S)-3-acetyl-2,2-dimethylcyclobutyl]-N-(p-tolyl)acetamide has been determined by single crystal X-ray diffraction analysis. The crystal belongs to triclinic system, space group P-1, a = 8.8700(18) Å, b = 10.331(2) Å, c = 10.363(2) Å, α = 71.11(3), β = 65.06(3), γ = 72.18(3), V = 798.6(3) Å3, Z = 2, formula unit C17H23NO2. The title compound has a fragment of 2,2-dimethylcyclobutane and its conformation represents semi-chair. The intermolecular hydrogen bonds N-H...O and C-H...O are revealed.