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Journal of Structural Chemistry

2012 year, number 4

1.
AN ATOMISTIC LEVEL DESCRIPTION OF GUEST MOLECULE EFFECT ON THE FORMATION OF HYDRATE CRYSTAL NUCLEI BY AB INITIO CALCULATIONS

R.V. Belosludov1, H. Mizuseki1, M. Souissi1, Y. Kawazoe1, J. Kudoh2, O.S. Subbotin3, T.P. Adamova3, V.R. Belosludov3
1 Institute for Materials Research, Tohoku University
2 Center for Northeast Asia Studies, Tohoku University
3 Nikolaev Institute of Inorganic Chemistry Siberian Branch of Russian Academy of Sciences
subbot@niic.nsc.ru
Keywords: methane, ozone, clathrate hydrate; nucleation mechanism; first-principles calculations
Pages: 633-639

Abstract >>
In the present study, we have reported the results of a systematic investigation of cage-like water structures using the first-principles calculations. These results show that, in the case of methane hydrate, the following nucleation mechanism can be revealed. The formation of small water cavities filled with methane is the first step of formation of methane hydrate. It is not necessary to occupy all dodecahedral cages by the guest molecules. After that the small cavities started to form the H-bonding network with surrounding water molecules and the small number of water molecules is enough for formation of stable hydrogen-bonding network. The structural information contained in such nuclei is conserved in the forming crystal. Moreover, it is also important the presence of methane molecule between small cages in order to prevent the adhesion of cavities. It has been found that the ozone molecule can also stabilize the small cage since the value of the interaction energy between the ozone guest and water host framework is very close to one obtained for methane case. However, ozone affects on the structure of large cavities and hence the second guest is necessary in order to stabilize the hydrate structure.



2.
Theoretical investigation of ozone hydrate formation conditions

O. S. Subbotin, T. P. Adamova, R. V. Belosludov, H. Mizuseki, Y. Kawazoe, V. R. Belosludov
Keywords: lattice dynamics, thermodynamic properties, phase transitions, clathrate hydrates, ozone, oxygen
Pages: 640-646

Abstract >>
Structural, dynamic, and thermodynamic properties of ozone, oxygen, and mixed ozone-oxygen hydrates are investigated. The thermodynamic stability regions of these hydrates are found. Ozone can form hydrates at ambient pressure and temperatures below 230 K. Strong dependence of the binary hydrate formation pressure on the ozone concentration in the gas phase is shown. In the formation of the hydrate, ozone concentrates in the hydrate phase. At an ozone concentration of 5 mol.% in the gas phase, the ozone content in the hydrate reaches 40%.



3.
ELECTRONIC STRUCTURE, FERMI SURFACE, AND CHEMICAL BONDING IN NEW LAYERED OXYSELENIDE: HgCuSeO

V. V. Bannikov, I. R. Shein, A. L. Ivanovskii
Keywords: layered HgCuSeO oxyselenide, electronic structure, chemical bonding, FLAPW-GGA, simulation
Pages: 647-651

Abstract >>
A full-potential FLAPW-GGA method is used to study for the first time the electronic structure of new layered HgCuSeO oxyselenide with a tetragonal structure. The band structure, density of electron states, Fermi surface, and effective atomic charges are obtained and analyzed; the coefficients of low-temperature heat capacity and paramagnetic Pauli susceptibility are estimated. It is shown that the new layered HgCuSeO phase can be characterized as non-magnetic ionic metal.



4.
Structure and electronic properties of the surface of alkali metal peroxides

D. V. Korabel'nikov, Y. N. Zhuravlev, M. V. Aleinikova
Keywords: peroxides, surface structure, surface states, layer, surface energy, surface relaxation, charges
Pages: 652-657

Abstract >>
The CRYSTAL09 program with the implemented B3PW hybrid density functional in a localized basis of atomic orbitals is used to determine the atomic and electronic structure of the surface of lithium, sodium, and potassium peroxides. Geometric parameters, surface energies, partial densities of states, electron density distributions, overlap populations, and atomic charges are calculated. It is found that the geometry relaxation has a characteristic depth up to ~10 Å, while the surface states are located in the upper layers at a depth up to ~2.5 Å. Structural displacements of atoms do not exceed ~0.2 Å; the charge of the upper surface layers is positive, whereas the energy state shifts relative to the bulk ones can reach ~1 eV. The surface energy of peroxides decreases with an increase in the atomic number of the cation.



5.
HAMILTONIAN for the electronic states of molecules in chemical transformations

L. A. Gribov, N. I. Prokof'eva
Keywords: quantum chemistry, chemical transformations, Hamiltonian for electronic states
Pages: 658-661

Abstract >>
Based on the migrating wave packet, it is shown what form the Schrödinger equation for electronic states should have in a quantum description of chemical transformations.



6.
DFT, AIM, AND NBO ANALYSES OF 1-METHYL-2-THIOXOIMIDAZOLIDIN-4-ONE TAUTOMERS AND THEIR COMPLEXES WITH IODINE

H. Tavakol1, T. Hadadi2, H. Roohi3
1 Department of Chemistry, Isfahan University of Technology
2 Department of Chemistry, University of Zabol
3 Department of Chemistry, Faculty of Science, University of Guilan
hosein_ta@yahoo.com
Keywords: tautomers, thioimidazoline, iodine complex, DFT, NBO, AIM
Pages: 662-671

Abstract >>
Thioimidazoline derivatives can be used to treat hyperthyroidism due to their ability to make complexes with iodine. In this research designed to find new structures with the same ability, 1-methyl-2-thioxoimidazolidin-4-one (MTIO) and the structures of MTIO tautomers (5 tautomers), their isomers (total 9 isomers) and their complexes with iodine are optimized using the B3LYP method with two different basis sets to obtain their molecular parameters, relative energies, and vibrational frequencies. The relative energies show that in all tautomers and complexes, ketone and thione forms are more stable than enol and thienol forms, and also Z isomers are more stable than E isomers. Moreover, the NBO calculation is carried out for tautomers and complexes to obtain atomic charges and acceptor-donor interactions. These results confirm the ability of MTIO tautomers to form complexes and show that the planar complexes have more effective interaction than the perpendicular complexes. The essence and important complexation properties are also calculated and confirmed using the AIM analysis.



7.
THEORETICAL STUDY ON DIMERS OF 2,6-DIAMINO-3,5-DINITROPYRIDINE AND ITS N-OXIDE

L.-F. Xie1, C.-C. Ye1, X.-H. Ju2, F.-Q. Zhao3
1 School of Chemical Engineering, Nanjing University of Science and Technology
2 School of Chemical Engineering, Nanjing University of Science and Technology Xi′an Modern Chemistry Research Institute, Xi′an
3 Xi′an Modern Chemistry Research Institute, Xi′an
xhju@mail.njust.edu.cn
Keywords: 2, 6-diamino-3, 5-dinitropyridine, 2, 6-diamino-3, 5-dinitropyridine-1-oxide, intermolecular interaction, first-principle calculations, natural bond orbital
Pages: 672-677

Abstract >>
First-principle calculations are performed on the dimers of 2,6-diamino-3,5-dinitropyridine (ANPy) and its N-oxide (2,6-diamino-3,5-dinitropyridine-1-oxide, ANPyO). The dimers as well as the monomers are fully optimized by the DFT-B3LYP and HF methods in conjunction with 6-311G**, 6-311++G**, and cc-pVDZ basis sets. The N-O bond length of the pyridine N-oxide moiety decreases in the ANPyO dimer in the dimerization process, which results in a larger deformation energy of the ANPyO submolecule. This deformation prevents the submolecules from further close contact and the formation of strong H-bonds between the nitro and amino groups. The optimized intermolecular distances of the ANPyO dimer are in good agreement with the corresponding experimental values. There is a weak C-H⋯O hydrogen bond in the ANPyO dimer; the B3LYP method underestimates its binding energy. On the contrary, for the ANPy dimer, the binding energy obtained at the B3LYP level is larger than that obtained at the HF level. The individual O⋯H strength is stronger in the ANPy dimer than that in ANPyO, which is consistent with the O⋯H distance. The O⋯H-C type of the H-bond is stronger in the ANPyO dimer than the ordinary O⋯H-C bond due to the N-oxide oxygen atom bearing larger negative charges. The corrected binding energy for each hydrogen bond between nitro oxygen and amino hydrogen is about -5 kJ/mol in the ANPy dimer, which is stronger than that in the ANPyO dimer.



8.
DFT CHARACTERIZATION OF 1-ACETYLPIPERAZINYLDITHIOCARBAMATE LIGAND AND ITS TRANSITION METAL COMPLEXES

S.A. Beyramabadi, A. Morsali, S.H. Vahidi
Department of Chemistry, Mashhad Branch, Islamic Azad University
beiramabadi6285@mshdiau.ac.ir
Keywords: density functional theory; PCM; Schiff base; IR assignment; NBO; dithiocarbamate; piperazine
Pages: 678-686

Abstract >>
Employing DFT and handling the solvent effects with the PCM model, the 1-acetylpiperazinyldithiocarbamate acpdtc ligand and its M(acpdtc)2 complexes, where M is Mn(II), Fe(II), Co(II), Ni(II) and Cu(II), are characterized computationally. The obtained results suggest that the piperazine ring adopts chair conformation in all the studied species. In the gas and solution phases, the chair form of the ligand is dominant. For the Mn, Fe and Co complexes the tetrahedral structure is more stable than the square form in the gas and solution phases. However, the Ni and Cu complexes adopt the square form, in which the complex has the inversion center. The calculated vibrational frequencies are in agreement with the experimental ones, confirming the suitability of the optimized geometries of the compounds. Atomic charges, electron distribution of the frontier orbitals, and stabilizing electron transfers are determined by the NBO analysis.



9.
A DFT STUDY ON THE STRUCTURE AND DETONATION PROPERTIES OF AMINO, METHYL, NITRO, AND NITROSO SUBSTITUTED 3,4,5-TRINITROPYRAZOLE-2-OXIDES: NEW HIGH ENERGY MATERIALS

P. Ravi1, G.M. Gore2, A.K. Sikder2, S.P. Tewari1
1 Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, P.O. Central University
2 High Energy Materials Research Laboratory (HEMRL)
rpiitb@hotmail.com
Keywords: 3, 4, 5-trinitropyrazole-2-oxides, density, detonation performance, impact sensitivity
Pages: 687-695



10.
ESR AND LUMINESCENCE OF ZnWO4 crystals activated by gadolinium ions

A. A. Ryadun, E. N. Galashov, V. A. Nadolinny, V. N. Shlegel
Keywords: luminescence, scintillators, zinc tungstate crystals, ESR of gadolinium ions
Pages: 696-700

Abstract >>
The crystals of zinc tungstate (ZTO) are a radiation-hardened matrix and are widely used as scintillators for high energy radiation. Therefore, it is interesting to study the possibility of introducing gadolinium ions into this structure to obtain the lasing properties. In order to activate ZTO crystals by gadolinium ions, 0.5 mol.% of Gd2O3 is added to the load. High-quality large crystals of ZTO are produced. The spectra of optical transmission, luminescence excitation, and luminescence are measured at room temperature. It is shown that the introduction of gadolinium ions does not result in a shift of the main luminescence band of the ZTO crystals. The analysis of the ESR spectra and their modeling enables the calculation of spin-Hamiltonian parameters. It is shown that the observed spectrum depends on the state of Gd3+ ions with S = 7/2 and is well described by the spin-Hamiltonian parameters gx = 1.9835, gy = 1.9685, gz = 1.9688 and D = 644.88 Gs, E = 161.49 Gs. Directions of the principal values of the D tensor are determined; they reflect a strong distortion of the nearest-neighbor oxygen environment.



11.
X-RAY SPECTROSCOPIC STUDY OF THE ELECTRONIC STRUCTURE OF BORON CARBONITRIDE FILMS OBTAINED BY CHEMICAL VAPOR DEPOSITION ON Co/Si AND COx/Si SUBSTRATES

Y. V. Fedoseeva, M. L. Kosinova, S. A. Prokhorova, I. S. Merenkov, L. G. Bulusheva, A. V. Okotrub, F. A. Kuznetsov
Keywords: boron carbonitride, X-ray photoelectron spectroscopy, near-edge X-ray absorption spectroscopy, electronic structure fine structure
Pages: 701-709

Abstract >>
Boron carbonitride films are synthesized by chemical vapor deposition from a mixture of triethylamine borane and ammonia on a metallic or oxidized cobalt sublayer sprayed over Si(100) substrates. Scanning electron microscopy shows that the surface of a BCxNy/Co/Si sample has a homogeneous fine-grained structure; filamentous entities are found on the surface of the BCxNy/CoOx/Si sample. The electronic structure of the films is investigated by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). An analysis of the spectra shows that BCxNy films are composed of graphite and hexagonal boron nitride (h-BN) regions and complex BCNyOz components with B-C, N-C, B-O, N-O, and C-O bonds. The deposition of the BCxNy film on the oxidized Co sublayer results in an increase in the number of -, N-O, B-O, and -N bonds and a decrease of the graphite and h-BN components and in the number of - bonds. The XPS data are used to estimate the surface elemental composition of the BCxNy/CoOx/Si sample. It is found that the film consists of 66 at.% graphite component and 3 at.% h-BN; the proportion of complex 0.46B0.11N0.05O0.38 components is 31 at.%.



12.
X-ray phOtoelectron and Auger spectroscopic study of the chemical composition of BCxNy films

V. G. Kesler, M. L. Kosinova, Y. M. Rumyantsev, V. S. Sulyaeva
Keywords: X-ray photoelectron spectroscopy, Auger spectroscopy, PECVD, BCxNy films
Pages: 710-717

Abstract >>
X-ray photoelectron and Auger spectroscopy are used to investigate the chemical composition of BCxNy films synthesized by PECVD from different initial gas mixtures in the temperature range 473-723 K. Main principles and features of the film formation are found. It is shown that the chemical composition of BCxNy films significantly depends on the synthesis parameters, which enables targeted control of their physical properties. The obtained data are discussed.



13.
STRUCTURE OF HfO2 FILMS AND BINARY OXIDES ON ITS BASE

T. P. Smirnova, L. V. Yakovkina, V. O. Borisov, V. N. Kichai, V. V. Kaichev, V. V. Kriventsov
Keywords: hafnium dioxide, binary solutions, high-k dielectrics
Pages: 718-724

Abstract >>
The chemical composition and structure of HfO2 films and binary oxides formed by their doping with aluminum and scandium are analyzed. It is shown that aluminum doping of HfO2 causes film amorphization: at the Al concentration above 30 at.% the film becomes amorphous. Scandium doping of HfO2 modifies the monoclinic structure, and in the Sc concentration range from ~9 at.% to ~14 at.% Sc under non-equilibrium conditions of the CVD process at 600C a solid solution film of the orthorhombic structure forms.



14.
PREPARATION OF THIN FILMS OF PLATINUM GROUP METALS BY PULSED MOCVD. I. DEPOSITION OF Ir LAYERS

N. V. Gelfond, N. B. Morozova, P. P. Semyannikov, S. V. Trubin, I. K. Igumenov, A. K. Gutakovskii, A. V. Latyshev
Keywords: iridium films, pulsed MOCVD, volatile compounds of iridium(I, III), high-temperature mass spectrometry
Pages: 725-734

Abstract >>
Pulsed MOCVD with the in situ mass spectrometric control of the deposition process is employed to obtain ultrathin Ir layers with a thickness from units to tens of nanometers. The role of the reaction medium, precursor nature, and deposition temperature in the formation of the nanocrystalline structure of films is revealed. The deposition of Ir from Ir(acac)3 in the oxygen atmosphere results in the formation of dense homogeneous structures, while in vacuum or in the hydrogen atmosphere, nanosized granular Ir layers are deposited. When Ir(CO)2(acac) is used, Ir films with a granular structure are obtained regardless of the reaction medium.



15.
PREPARATION OF THIN FILMS OF PLATINUM GROUP METALS BY PULSED MOCVD. II. DEPOSITION OF Ru LAYERS

N. B. Morozova, N. V. Gelfond, P. P. Semyannikov, S. V. Trubin, I. K. Igumenov, A. K. Gutakovskii, A. V. Latyshev
Keywords: volatile complexes of ruthenium(II, III) with organic ligands, high-temperature mass spectrometry, thermal decomposition processes, pulsed MOCVD
Pages: 735-743

Abstract >>
In situ high-temperature mass spectrometry is used to analyze the thermal decomposition of Ru(acac)3 and Ru(nbd)(allyl)2 vapor and possible schemes of thermal transformations on the heated surface. By pulsed MOCVD with in situ mass spectrometric control of deposition processes ultrathin Ru layers with a thickness of several nanometers are obtained. The role of the reaction medium, precursor nature, and deposition temperature in the formation of a nanocrystalline structure of the films is revealed. Ruthenium films with a compact continuous structure are formed from Ru(acac)3 and hydrogen at a deposition temperature of 340C and below; an increase in the temperature results in the growth of nanogranular Ru layers. Regardless of deposition conditions, from Ru(nbd)(allyl)2 granular nanocrystalline Ru layers are formed.



16.
crystallographic analysis of microtwin STRUCTURES of sulfides: the case study of lillianite and HEYROVSKYITE

S. V. Borisov, S. A. Magarill, N. V. Pervukhina
Keywords: microtwining, lillianite, heyrovskyite, sulfides, sulfosalts, tablet structures, structure-determining factors, cation and anion sublattices, building blocks, crystallographic analysis
Pages: 744-750

Abstract >>
Crystal structures of the minerals lillianite Pb3Bi2S6 and heyrovskyite Pb6Bi2S9 are subjected to crystallographic analysis to demonstrate that the microtwinning of the structure-forming 2D layer fragments occurs within common cation and anion matrices. A combination of the PbS-type structural fragments with different orientations is achieved by vacant sites in the cation and anion translational sublattices without their noticeable distortion. In the structure of β-Pb3Bi2S6 (the high-pressure phase of lillianite), the pseudo-translational ordering of cations and anions as well as the overall symmetry of the structure are significantly lowered, while the general arrangement is preserved.



17.
CRYSTAL STRUCTURES OF 1,1,1-TRIFLUORO-4-HYDROXY-4-PHENYL-BUT-3-EN-2-ONE, 2,2,6,6-TETRAMETHYL-3-HYDROXY-HEPT-3-EN-5-ONE, 2,2,6,6- TETRAMETHYL-3-METHYLAMINO-HEPT-3-EN-5-ONE AND A STUDY OF THE ABILITY OF THESE LIGANDS TO COMPLEX FORMATION WITH METALS

P. A. Stabnikov, L. G. Bulusheva, N. I. Alferova, A. I. Smolentsev, I. V. Korol'kov, N. V. Pervukhina, I. A. Baidina
Keywords: ?-diketones, crystal structure, molecular packing, chelate formation
Pages: 751-757

Abstract >>
Crystal structures are determined (Bruker Nonius X8 Apex, 4 CCD-detector, λMoKα, graphite monochromator, T 150 K and 293 K) for two β-diketones F3CC(O)CH2C(O)Ph (1) (space group P21/c, a = 7.0713(3) Å, b = 11.5190(6) Å, c = 11.3602(6) Å, β = 99.405(2), V = 912.90(8) Å3, Z = 4), (CH3)3CC(O)CH2C(O)C(CH3)3 (2) (space group Pbca, a = 11.5536(8) Å, b = 11.5796(10) Å, c = 17.2523(13) Å, V = 2308.1(3) Å3, Z = 8) and a ketoimine (CH3)3CC(NCH3)CH2C(O)C(CH3)3 (3) (space group I41/a, a = 18.7687(6) Å, b = 18.7687(6) Å, c = 14.5182(6) Å, V = 5114.2(3) Å3, Z = 16). All structures are molecular and comprise isolated molecules joined by van der Walls interactions. The substitution energy of a Na atom for a hydrogen atom in free ligands is calculated by the hybrid B3LYP quantum chemical method. A successful preparation of Na(I) chelates with ligands 1, 2 and failed attempts to prepare a complex with ligand 3 are in accordance with the calculations. Geometrical simulation of a copper(II) complex with ligand 3 reveals the overlap of 3 groups which hinders the complexation.



18.
[Co(NH3)6](WO4)Cl: SYNTHESIS, CRYSTAL STRUCTURE, AND THERMAL PROPERTIES

S. P. Khranenko, A. V. Alexeyev, D. Y. Naumov, P. E. Plusnin, S. A. Gromilov
Keywords: tungsten, cobalt, complex salt, crystal chemistry, single crystal X-ray diffraction study, thermal properties
Pages: 758-762

Abstract >>
The crystal structure of [Co(NH3)6](WO4)Cl complex salt is determined by single crystal X-ray. The thermal properties are examined, and the products obtained on heating the salt in different gaseous atmospheres are analyzed by powder X-ray diffraction.



19.
CRYSTAL STRUCTURE OF 2{[H(1,10-C12H8N2)]2[(B9C2H11) CoIII(B8C2H10)CoIII(B9C2H11)]}3CH3CN3H2O

T. M. Polyanskaya, M. K. Drozdova, V. V. Volkov
Keywords: crystal structure, cobalt, binuclear cluster, phenanthrolinium, ortho-carborane(12) derivatives, acetonitrile, water
Pages: 763-770

Abstract >>
Single crystals are grown and X-ray diffraction analysis of a new compound containing a dicobalt carborane cluster anion of a Co(III) atom with the composition 2{[HPhen]2[(B9C2H11) Co(B8C2H10)Co(B9C2H11)]}3CH3CN3H2O (Phen = 1,10-phenanthrolinium) is carried out. The crystallographic dat a: C66H115B52N11O3Co2, M = 1908.53, orthorhombic system, space group Pbca, unit cell parameters a = 14.5297(6) , b = 27.1276(11) , c = 47.4274(20) , V = 18694 3, Z = 8, dcalc = 1.356 g/cm3, T = 153 K, F(000) = 7840, = 0.750 mm-1. The structure is solved by the direct and Fourier methods and refined using full-matrix LSM in the anisotropic (isotropic for hydrogen atoms) approximation to the final factors R1 = 0.0500, wR2 = 0.1165 for 13651 Ihkl e 2I out of 65158 measured Ihkl (Bruker Nonius X8 Apex diffractometer, MoK radiation, graphite monochromator). The structure is composed of 12 crystallographically independent building units, i.e.: four [HPhen]+ cations, two [(B9C2H11)Co(B8C2H10)Co(B9C2H11)]2- anions, three molecules of CH3CN acetonitrile, and three water molecules. The anion has a chain structure consisting of three icosahedra sharing vertices occupied by cobalt atoms. The arrangement of -C2- groups in the anion corresponds to the quasi-gauch-configuration of asymmetric sandwich complexes of both cobalt atoms.



20.
crystal structures of hafnium(IV) and zirconium(IV) complexes with β-diketones

K. V. Zherikova, N. B. Morozova
Keywords: hafnium(IV), zirconium(IV), ?-diketonates, mass-spectrometry, IR spectroscopy, X-ray crystallography
Pages: 771-777

Abstract >>
Preparation methods are developed for a number of 7- and 8-coordinated derivatives of Hf(IV) and Zr(IV) with β-diketonate ligands (R1-O-H-O-R2). The complexes obtained are examined by IR spectroscopy, mass spectrometry, and X-ray crystallography. All structures are molecular. The M-O distances fall within 2.09-2.28 Å. In the crystals, the molecules are joined only by van der Waals interactions. It is demonstrated that the series of hafnium(IV) and zirconium(IV) chelates with identical ligands are isostructural, and the introduction of CF3- or tert-butyl groups in the terminal positions of the ligand as well as chlorine substitution for one of the ligands do not essentially affect the basic geometric characteristics of the ligand in the complexes.



21.
single crystal X-Ray Diffraction study of the cubic ionic clathrate hydrate of tetrabutyl ammonium propionate (C4H9)4NC2H5COO27.0H2O

V. Y. Komarov, T. V. Rodionova, K. Suwinska
Keywords: ionic clathrate hydrates, tetrabutyl ammonium propionate, structure, disordering
Pages: 778-785

Abstract >>
Single crystal X-ray diffraction is used for the first time to study the structure of the ionic clathrate hydrate of tetrabutyl ammonium propionate (C4H9)4NC2H5COO27.0H2O with the host framework based on cubic arrangement I. The structural model is characterized by a high degree of disordering in both guest and host subsystems. The structural features indicate a colocation of cations and anions in multicell 4TnD cavities with n = 0-4; the simplest option is a pairwise location of cations and anions in combined five-cell 4TD cavities. The positional ordering of cations leads to the formation of a 2×2×2 supercell (space group I3d, a = 24.312(6) Å). The resulting model confirms the characteristic features of ionic clathrate hydrates of tetrabutyl and tetraisoamyl ammonium carboxylates. Non-standard refinement techniques are described, which may be of interest for other structures with a high degree of disordering. The proposed structural interpretation can serve as a basis for a further investigation of this class of compounds by other methods.



22.
CRYSTAL STRUCTURE OF A NICKEL(II) COMPLEX WITH THE MACROCYCLIC LIGAND 4-METHYL-1,3,5,8,11,14-HEXAAZATRICYCLOOCTADECANE

X. Jiang, H. Xia, G. Yan, B. Tao, Y.-F. Zhu, X. Wang
Faculty of Materials Science and Chemistry Engineering, China University of Geosciences
Keywords: Ni(II), macrocyclic complex, crystal structure, PCHA, supermolecular interaction
Pages: 786-789

Abstract >>
The crystal structure of the macrocyclic complex [Ni(PCHA)](ClO4)2 (II) (PCHA = 4-methyl-1,3,5,8,11,14-hexaazatricyclooctadecane) is described. In the presence of succinate acid, [Ni(PCHA)](ClO4)2 (II) is obtained by recrystallization of orange crystals of [Ni(PCHA)](ClO4)2 (I), whose structure has previously been identified. The [Ni(PCHA)](ClO4)2 (II)crystal belongs to the monoclinic P2(1)/c space group with a = 15.8561(3) Å, b = 9.4409(2) Å, c = 13.9297(2) Å, α = 90, β = 94.8840(10), γ = 90, Mr = 526.02, Z = 4, V = 2077.65(7) Å. The structure is ionic with [Ni(L)]2+ and two perchlorate anions with a supermolecular interaction.



23.
CRYSTAL STRUCTURES OF DIMOLYBDENUM CARBONYL COMPLEXES CONTAINING THE CYCLOPENTADIENYL-THIENYL LIGAND

J.-W. Wang1, L.-J. Tian1, Z.-H. Ma2, K.-M. Guo1, Z.-G. Han1, X.-Z. Zheng1, J. Lin1
1 College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, People′s Republic of China
2 College of Basic Medicine, Hebei Medical University, Shijiazhuang, People′s Republic of China
Pages: 790-795



24.
STRUCTURE AND STEREOCHEMICAL ASSIGNMENT OF SPHEROPSIDONE, A PHYTOTOXIN FROM DIPLODIA CUPRESSI

A. Tuzi1, A. Andolfi1, L. Maddau2, M. Masi1, A. Evidente1
1 Dipartimento di Scienze del Suolo, della Pianta, dell′Ambiente e delle Produzioni Animali, Università di Napoli
2 Dipartimento di Protezione delle Piante-Sezione di Patologia Vegetale, Università di Sassari
Keywords: spheropsidone, phytotoxin, Diplodia cupressi, X-ray structure, derivative stereochemistry
Pages: 796-801

Abstract >>
Sphaeropsidone is a phytotoxin produced in very large amount from Diplodia cupressi. It crystallizes in the monoclinic P21 space group with two molecules in the asymmetric unit. Cell parameters are: a = 4.1280(6), b = 13.161(1), c = 13.333(3) Å, β = 90.14(1), Z = 4, Dcal = 1.432 Mg/m3 at 173 K. The final refinement converged to R1 = 0.0413, wR2 = 0.0730 for 1684 observed reflections. In sphaeropsidone, the hydroxyl group and oxirane oxygen atoms are mutually cis positioned. The absolute stereochemistry at the three chiral centres turns out to be 1S,5R,6S. The stereochemical assignment of spaeropsidone is a fundamental basis for the assignment of the absolute configuration of some of its derivatives used in structure-activity relationship studies. No intramolecular hydrogen bonds are found. In the crystal packing, the hydroxyl and carbonyl oxygen atoms are involved in head-to-tail intermolecular hydrogen bonds to form infinite linear chains of molecules running along c. The linear chains are arranged into layers of molecules stacked along a.



25.
CRYSTAL STRUCTURES OF 4-(OXIRAN-2-YLMETHOXY)BENZOIC ACID AND 4-ACETOXYBENZOIC ACID

A. Obreza1, F. Perdih2
1 Faculty of Pharmacy, University of Ljubljana
2 Faculty of Chemistry and Chemical Technology, University of Ljubljana CO EN-FIST, Ljubljana
franc.perdih@fkkt.uni-lj.si
Keywords: crystal structure, epoxide, hydrogen bond, carboxylic acid
Pages: 802-808

Abstract >>
Compounds 4-(oxiran-2-ylmethoxy)benzoic acid (2) and 4-acetoxybenzoic acid (4) are synthesized by a new synthetic route and studied by X-ray crystallography. Compound 2 crystallizes in the monoclinic system, P21/n space group, a = 5.1209(2) Å, b = 30.3429(16) Å, c = 5.9153(3) Å, β = 96.725(3), V = 912.81(8) Å3, Z = 4. Compound 4 crystallizes in the triclinic system, P-1 space group, a = 7.3400(4) Å, b = 8.0819(3) Å, c = 15.6548(9) Å, α = 85.754(3), β = 84.268(2), γ = 70.023(3), V = 867.63(8) Å3, Z = 4. The crystal structure of 2 comprises two crystallographically independent molecules of the compound. In the crystal structures of 2 and 4, pairs of molecules form carboxyl dimers.



26.
STRUCTURAL FEATURES AND CONDUCTIVITY OF SILICON FILMS: SIMULATION AND EXPERIMENT

P. L. Novikov, O. I. Semenova, V. G. Shchukin, R. G. Sharafutdinov
Keywords: thin film solar cells, conductivity of thin films, Monte Carlo method, percolation cluster
Pages: 809-813

Abstract >>
Structural and photoelectric properties of low-temperature silicon microcrystalline layers are studied. The layers are obtained by a new method of electron-beam plasma produced by the electron beam interaction with the supersonic flow of initial gas mixtures. Based on the experiments and Monte Carlo calculations it is found that the dependence of the μc-Si:H layer conductivity on the degree of crystallinity of the material is described within percolation theory.



27.
On The Formation of THE crystalline Phases and nanostructure of SILICON CARBONITRIDE layers grown on gallium arsenide substrates

N. I. Fainer, V. I. Kosyakov, Y. M. Rumyantsev, E. A. Maximovskii
Keywords: silicon carbonitride, structure, vapor-liquid-solid (VLS) mechanism, thin films, nanocrystals, gallium arsenide substrates
Pages: 814-820

Abstract >>
The crystallization of thin silicon carbonitride layers obtained by chemical vapor deposition from silicon organic precursors on gallium arsenide substrates at 973 K in the presence of liquid gallium drops is studied. The layers grown by the vapor-liquid-solid method are studied by IR, Raman, and energy dispersive spectroscopy, scanning electron microscopy, and X-ray diffraction using synchrotron radiation in order to determine their chemical and phase composition, crystal structure, and surface morphology. Their morphology is supposed to be associated with the formation of nuclei in a gallium drop located at the surface of the gallium arsenide substrate.



28.
Composition and structure of silicon carbonitride layers grown on Si(100)/(Fe, Ni, Co) substrates

N. I. Fainer, V. I. Kosyakov, Y. M. Rumyantsev, E. A. Maximovskii, S. A. Prokhorova, P. N. Gevko
Keywords: silicon carbonitride, structure, thin films, crystal shapes, Si(100) substrates, Fe-Ni-Co alloy, IR spectroscopy, Raman spectroscopy, AFM, SEM, SR-XRD
Pages: 821-827

Abstract >>
The phase and chemical composition of silicon carbonitride films obtained by plasma-enhanced chemical vapor deposition on Si(100) substrates and the same substrates covered by a layer of (Fe, Ni, Co) alloy is studied. It is shown that substrate metallization practically does not change the chemical composition of the film, but affects the ratio phases present in the film and the film nanostructure.