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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Molokeev M. S., Bogdanov E. V., Misyul S. V., Tressaud A., Flerov I. N.
Заглавие : Crystal structure and phase transition mechanisms in CsFe2F6
Место публикации : J. Solid State Chem. - 2013. - Vol. 200. - P.157-164. - DOI 10.1016/j.jssc.2013.01.038
Аннотация: For the first time, structural phase transitions induced by the temperature were found in AxMxIIM(1−x)IIIF3 fluorides with the defect pyrochlore structure (Fdm, Z=8). The room temperature structure of CsFe2F6 was determined using X-ray powder diffraction technique. This phase was found to be ordered with the Pnma space group. The study of the temperature stability of orthorhombic structure by differential scanning calorimeter between 100 K and 700 K has shown a succession of phase transitions. The Pnma (Z=4)→Imma (Z=4)→I41/amd (Z=4)→Fdm (Z=8) structural sequence was proposed to occur within a rather narrow temperature range 500–560 K. The mechanism of structural transition has been mainly associated with the rotation of (MF6) octahedra and small displacements of some Fe atoms. This assumption is in good agreement with the low experimental entropy value, which is characteristic for displacive transformations.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu.V., Ivanova N. B., Kazak N. V., Platunov M. S., Bezmaternykh L. N., Velikanov D. A., Vasiliev A. D., Ovchinnikov S. G., Yurkin G. Yu.
Заглавие : Crystal structure and magnetic properties of Mn substituted ludwigite Co3O2BO3
Место публикации : J. Magn. Magn. Mater.: Elsevier Science BV, 2012. - Vol. 324, Is. 6. - P.923-927. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2011.07.044
Примечания : Cited References: 15. - The study was supported by the Russian Foundation for Basic Research (Project no. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (Project no. MK-5632.2010.2), the Physical Division of the Russian Academy of Science, the program "Strongly Correlated Electrons", Project 2.3.1.
Предметные рубрики: BOND VALENT SUMS
COORDINATION CHEMISTRY
OXIDATION -STATE
O BONDS
COMPLEXES
MANGANESE
COBALT
Ключевые слова (''Своб.индексиров.''): transition metal oxyborate--distinct crystallographic position--spin glass magnetic ordering
Аннотация: The needle shape single crystals Co3−x MnxO2BO3 with ludwigite structure have been prepared. According to the X-ray diffraction data the preferable character of distinct crystallographic positions occupation by Mn ions is established. Magnetization field and temperature dependencies are measured. Paramagnetic Curie temperature value Θ=−100 K points out the predominance of antiferromagnetic interactions. Spin-glass magnetic ordering takes the onset at TN=41 K. The crystallographic and magnetic properties of Co3O2BO3:Mn are compared with the same for the isostructural analogs Co3O2BO3 and CoO2BO3:Fe.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Astakhov A. M., Vasiliev A. D., Revenko V. A.
Заглавие : Crystal and molecular structure of 1-phenyl-2-nitroguanidine
Место публикации : J. Struct. Chem.: Springer, 2012. - Vol. 53, Is. 5. - P.1013-1016. - ISSN 0022-4766, DOI 10.1134/S0022476612050265
Примечания : Cited References: 12
Ключевые слова (''Своб.индексиров.''): nitrimines--nitroguanidine--single crystal x-ray diffraction study--molecular structure
Аннотация: The molecular structure of 1-phenyl-2-nitroguanidine is nonplanar, but contains two almost planar fragments: nitroguanyl and phenyl groups. Unlike previously studied nitroguanidines, in 1-phenyl-2-nitroguanidine, the nitro group is turned to the secondary amino group. However, the structural parameters of the nitroguanyl group are little different from those of nitroguanidine and its alkyl derivatives. In the benzene ring, the symmetry in the geometric parameters is not observed, which is explained by the intermolecular interaction with the neighboring molecule.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Isaenko L. I., Kesler V. G., Lin Z. S., Molokeev M. S., Yelisseyev A. P., Zhurkov S. A.
Заглавие : Exploration on anion ordering, optical properties and electronic structure in K3WO3F3 elpasolite
Место публикации : J. Solid State Chem. - 2012. - Vol. 187. - P.159-164. - ISSN 0022-4596, DOI 10.1016/j.jssc.2011.12.037
Примечания : Cited References: 50. - This study is partly supported by SB RAS Project No. 34. ZSL acknowledges the funding support of No. 91022036, 11174297, 2010CB630701, and 2011CB922204 in China. Authors also wish to thank V. D. Fokina for microcaloric measurements.
Предметные рубрики: PHASE-TRANSITIONS
CRYSTAL-GROWTH
FERROELECTRIC K3WO3F3
SOLID-STATE
OXYFLUORIDE
FLUORIDE
POLAR
CS
(NH4)(3)MOO3F3
APPROXIMATION
Anion ordering
Chemical routes
Elpasolite
First-priciples calculation
Forbidden band
Low temperatures
Non-linear optical coefficients
Nonlinear optical crystal
Optical transparency
Oxyfluorotungstate
Room temperature
Ключевые слова (''Своб.индексиров.''): oxyfluorotungstate--structure--nonlinear optical crystals--electronic and optical properties--first-principles calculations
Аннотация: Room-temperature modification of potassium oxyfluorotungstate, G(2)-K3WO3F3, has been prepared by low-temperature chemical route and single crystal growth. Wide optical transparency range of 0.3-9.4 mu m and forbidden band gap E-g=4.32 eV have been obtained for G(2)-K3WO3F3 crystal. Meanwhile, its electronic structure has been calculated with the first-principles calculations. The good agreement between the theorectical and experimental results have been achieved. Furthermore, G(2)-K3WO3F3 is predicted to possess the relatively large nonlinear optical coefficients. (C) 2012 Elsevier Inc. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Avramov P. V., Fedorov D. G., Sorokin P. B., Sakai S., Entani S., Ohtomo M., Matsumoto Y., Naramoto H.
Заглавие : Intrinsic edge asymmetry in narrow zigzag hexagonal heteroatomic nanoribbons causes their subtle uniform curvature
Место публикации : J. Phys. Chem. Lett. - 2012. - Vol. 3, Is. 15. - P.2003-2008. - ISSN 1948-7185, DOI 10.1021/jz300625t
Примечания : Cited References: 42. - This work was supported by JAEA Research fellowship (P.V.A.). P.V.A. also acknowledges JAEA ASRC and the Molecular Spintronics Group for hospitality and fruitful collaboration. D.G.F. thanks Prof. Kazuo Kitaura for many fruitful discussions and the Next Generation SuperComputing Project, Nanoscience Program and Strategic Programs for Innovative Research (MEXT, Japan) for financial support. This work was partially supported by Russian Ministry of Education and Science (Contract No. 16.552.11.7014) (P.B.S.).
Предметные рубрики: MOLECULAR-ORBITAL METHOD
WALLED CARBON NANOTUBES
GRAPHENE NANORIBBONS
ELECTRONIC-STRUCTURE
OPTICAL-TRANSITIONS
SOLIDS
BOND
Aromatic rings
Conical surfaces
Finite length
Fragment molecular orbital methods
Graphene nanoribbons
Intrinsic curvature
Nanoribbons
Out-of-plane
Structural stress
Ключевые слова (''Своб.индексиров.''): zigzag nanoribbons--hexagonal atomic lattices--fluorine-terminated graphene
Аннотация: The atomic and electronic structure of narrow zigzag nanoribbons with finite length, consisting of graphene terminated by fluorine on one side, hexagonal (h) h-BN, and h-SiC were studied with density functional theory. It is found that the asymmetry of nanoribbon edges causes a uniform curvature of the ribbons due to structural stress in the aromatic ring plane. Narrow graphene nanoribbons terminated with fluorine on one side demonstrate a considerable out-of-plane bend, suggesting that the nanoribbon is a fraction of a conical surface. It is shown that the intrinsic curvature of the narrow nanoribbons destroys the periodicity and results in a systematic cancellation of the dipole moment. The in- and out- of-plane curvature of thin arcs allows their closure in nanorings or cone fragments of giant diameter. Using the fragment molecular orbital method, we optimized the structure of a planar giant arc and a closed ring of h-BN with a diameter of 105 nm.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Mean polarizability of molecules and anisotropy of the Lorentz tensor upon a nematic-smectic a phase transition: Their behavior in a homologous series
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 86, Is. 5. - P.720-728. - ISSN 0036-0244, DOI 10.1134/S0036024412050044
Примечания : Cited References: 37
Предметные рубрики: CHOLESTERIC LIQUID-CRYSTALS
REFRACTIVE-INDEX DATA
A PHASE
MESOMORPHIC PROPERTIES
ORIENTATIONAL ORDER
OPTICAL ANISOTROPY
LOCAL-FIELD
POLYMORPHISM
TEMPERATURE
A-monotone
Alkyl chain
Experimental values
Homologous series
Homologues
Limiting values
Lorentz
Mesophases
Molecular core
Molecular polarizabilities
Nematic
Orientational order parameters
Polarizabilities
Polarizability density
Quadratic dependence
A-monotone
Smectic
Smectic phase
Smectic phasis
Smectic-A phasis
Ключевые слова (''Своб.индексиров.''): molecular polarizability--anisotropy--phase transition--nematic--smectic--homologues
Аннотация: Experimental values of the mean polarizability of molecules, (gamma) over bar, and components of the Lorentz tensor, L-j, in the nematic and smectic A phases are obtained for a homologous series of n-alkyl-p-(4-ethoxybenzylideneamino)-alpha-methylcinnamates. Dependences of the (gamma) over bar and L-j values on the mesophase temperature, the orientational order parameter S of molecules, and the number n in the homologous series are revealed. The quadratic dependence of (gamma) over bar (S) in the nematic and smectic phases is established that is invariant with respect to the nematic-smectic A transition. Polarizability densities of the molecular core and the alkyl chain are found from the monotone decreasing dependence (gamma) over bar (n)/v (where v is volume per one molecule) in the smectic phase. The presence (or absence) of the odd-even alternation of L-j(n) in the nematic (smectic) phase is shown. A monotone decrease in the Lorentz tensor anisotropy L with an increase in n is revealed in the smectic phase, and limiting values L-j(n - infinity) are determined.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuzubov A. A., Eliseeva N. S., Krasnov P. O., Tomilin F. N., Fedorov A. S., Tolstaya A. V.
Заглавие : Possibility of a 2D SiC monolayer formation on Mg(0001) and MgO(111) substrates
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 87, Is. 8. - P.1332-1335. - ISSN 0036-0244, DOI 10.1134/S0036024413080141
Примечания : Cited References: 25
Предметные рубрики: AB-INITIO
THIN-FILMS
NANOTUBES
ENERGY
Ключевые слова (''Своб.индексиров.''): silicon carbide monolayer--density functional theory
Аннотация: The geometrical characteristics of a 2D SiC monolayer on Mg(0001) and MgO(111) plates regarded as potential materials for growing two-dimensional silicon carbide were studied. The most favorable positions of the atoms of 2D SiC on the substrates were determined. In the 2D SiC/Mg(0001) system, unlike in 2D SiC/MgO(111), the deviation of the carbon atom from the silicon carbide monolayer was insignificant (0.08 ). Consequently, magnesium can be used as a substrate for growing two-dimensional silicon carbide. The use of MgO(111) is not recommended because of a significant distortion of the 2D SiC surface.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vasiliev A. D., Zel'bst E. A., Soldatenko A. S., Bolgova Yu.I., Trofimova O. M., Voronkov M. G.
Заглавие : Synthesis and molecular structure of cobalt(II) complex with 1-(1-silatranylmethyl)-1,2,4-triazole
Место публикации : Struct. Chem.: Springer/Plenum Publishers, 2013. - Vol. 24, Is. 4. - P.1001-1005. - ISSN 1040-0400, DOI 10.1007/s11224-012-0121-0
Примечания : Cited References: 24
Предметные рубрики: REACTIVITY
DERIVATIVES
CRYSTAL
SPECTRA
Ключевые слова (''Своб.индексиров.''): complexes--1-(1-silatranylmethyl)-1,2,4-triazole--cobalt dichloride--x-ray diffraction
Аннотация: Reaction of cobalt chloride with 1-(1-silatranylmethyl)-1,2,4-triazole in benzene afforded complex CoCl2 center dot 2L (L = 1-(1-silatranylmethyl)-1,2,4-triazole). It was isolated as the solvate [CoCl2 center dot 2L]center dot CH2Cl2 (1) by recrystallization from dichloromethane and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the monoclinic space group P2(1)/m with a = 6.798(2) E, b = 20.326(5) E, c = 11.005(3) E, and Z = 4. The cobalt atom is in slightly distorted square-planar environment, coordinated to two nitrogen atoms from two ligands and two chloride ions.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Belash M. Y.
Заглавие : Crystal structure of potassium 2-thiobarbiturate
Место публикации : J. Struct. Chem.: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 54, Is. 3. - P.566-570. - ISSN 0022-4766, DOI 10.1134/S0022476613030141
Примечания : Cited References: 18. - The work was supported by the grant of the President of the Russian Federation for the support of leading scientific schools of the Russian Federation (NSh-4828.2012.2) and the Federal Targeted Program "Scientific and Scientific Pedagogical Personnel of Innovative Russia, 2009-2013" (State contracts Nos. 02.740.11.0269 and 02.740.11.0629).
Предметные рубрики: ACID
Ключевые слова (''Своб.индексиров.''): crystal structure--potassium thiobarbiturate--hydrogen bonds--pi-pi interaction
Аннотация: The crystal and molecular structure of potassium thiobarbiturate C4H3KN2O2S (C4H4N2O2S-2-thiobarbituric acid, H(2)TBA) is determined. Crystallographic data for KHTBA are as follows: a = 11.2317(17) , b = 3.8687(6) , c = 14.557(2) , beta = 97.448(4)A degrees, V = 627.18(17) (3), space group P2/c, Z = 4. Each potassium ion is linked with four oxygen atoms and two S atoms forming a distorted octahedron. N-HaEuro broken vertical bar O and C-HaEuro broken vertical bar S hydrogen bonds form a branched three-dimensional network. The structure is also stabilized by the pi-pi interaction of heterocyclic HTBA(-) ions.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vasiliev A. D., Golovnev N. N.
Заглавие : Crystal structure of two hydrate phases of ciprofloxacindi-um tetrachloridocobaltate(II)
Место публикации : J. Struct. Chem.: MAIK Nauka-Interperiodica / Springer, 2013. - Vol. 54, Is. 3. - P.607-612. - ISSN 0022-4766, DOI 10.1134/S0022476613030219
Примечания : Cited References: 9
Ключевые слова (''Своб.индексиров.''): ciprofloxacindi-um tetrachloridocobaltate(ii)--crystal structure--hydrogen bonds--pi-pi interaction
Аннотация: New (C17H20FN3O3)(2)[CoCl4](2)center dot 3H(2)O (I) and C17H20FN3O3[CoCl4]center dot H2O (II) compounds, where C17H18FN3O3 is ciprofloxacin (CfH), are synthesized and their crystal structures are determined. Crystallographic data for I: a = 18.441(5) , b = 9.030(3) , c = 27.551(8) , V = 4588(4) (3), space group Pca2(1), Z = 4; for II: a = 9.305(3) , b = 9.885(3) , c = 12.999(4) , alpha = 82.782(4)A degrees, beta = 72.954(4)A degrees, gamma = 89.736(4)A degrees, V = 1133(1) (3), P-1 space group, Z = 2. Both structures contain CfH (3) (2+) ion pairs bonded by the pi-pi interaction. Additionally, in the crystal of I there is a stacking interaction between the pi clouds of aromatic rings and hydrogen atoms of the cyclopropyl group linking the pairs of molecules with each other. The structure of the centrosymmetric crystal of triclinic phase II is also formed from CfH (3) (2+) ion pairs bonded by the pi-pi interaction, which, in this case, are not independent because they are related by the symmetry center. Hydrogen bonds form a branched three-dimensional network linking the CfH (3) (2+) and CoCl (4) (2-) ions and water molecules.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belousov O. V., Borisov R. V., Zharkov S. M., Parfenov V. A., Dorokhova L. I.
Заглавие : Redox potentials of gold-palladium powders in aqueous solutions of H2PdCl4
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 86, Is. 3. - P.484-488. - ISSN 0036-0244, DOI 10.1134/S0036024412020070
Примечания : Cited References: 26
Предметные рубрики: BIMETALLIC NANOPARTICLES
METALLIC PALLADIUM
COPPER
ELECTRODE
BLACK
Bimetallic particles
Bimetallic powders
Gold-palladium
Hydrochloric acid solution
Nernst equation
Redox potentials
Gold
Hydrochloric acid
Redox reactions
Secondary batteries
Transmission electron microscopy
X ray diffraction analysis
Ключевые слова (''Своб.индексиров.''): bimetallic powders--gold-palladium--redox potential
Аннотация: The redox potential of fine-dispersed and compact bimetallic powders of the palladium-gold system in hydrochloric acid solutions of H2PdCl4 at a temperature of 60A degrees C was studied. It was found that the redox potential increases with gold enrichment of the solid solution in accordance with the Nernst equation. The effect of gold-palladium particle size on this redox potential is shown. The morphology, sizes, and composition of bimetallic particles are determined via transmission electron microscopy and X-ray diffraction analysis.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Antipina L. Yu., Tomilin F. N., Vysotski E. S., Ovchinnikov S. G.
Заглавие : A quantum chemical study of the formation of 2-hydroperoxy-coelenterazine in the Сa2+-regulated photoprotein obelin
Место публикации : J. Struct. Chem.: Springer, 2011. - Vol. 52, Is. 5. - P.870-875. - ISSN 0022-4766
Примечания : Cited References: 19. - The work was supported by RFBR (07-04-00930-a), the "Molecular and Cell Biology" Program of the Presidium of the Russian Academy of Sciences, and the Program of the Siberian Division of the Russian Academy of Sciences (project No. 2) within the implementation of the Federal Targeted Program "Scientific and Scientific Pedagogical Personnel of Innovative Russia, 2010" (P333 and P213).
Предметные рубрики: CALCIUM-DISCHARGED OBELIN
SEMIEMPIRICAL METHODS
1.7 ANGSTROM
OPTIMIZATION
PARAMETERS
MECHANISM
FLUORESCENCE
ELEMENTS
PROTEIN
EMITTER
Ключевые слова (''Своб.индексиров.''): coelenterazine--2-hydroperoxy-coelenterazine--obelia longissima--renilla muelleri
Аннотация: The Ca2+-regulated photoprotein obelin determines the luminescence of the marine hydroid Obelia longissima. Bioluminescence is initiated by calcium and appears as a result of the oxidative decarboxylation related to the coelenterazine substrate. The luciferase of the luminescent marine coral Renilla muelleri (RM) also uses coelenterazine as a substrate. However, three proteins are involved in the in vivo bioluminescence of these animals: luciferase, green fluorescent protein, and Ca2+-regulated coelenterazine-binding protein (CBP). In fact, CBP that contains one strongly bound coelenterazine molecule is the RM luciferase substrate in the in vivo bioluminescent reaction. Coelenterazine becomes available for oxygen and the reaction with luciferase only after binding CBP with calcium ions. Unlike Ca2+-regulated photoproteins, the coelenterazine molecule is not activated by oxygen in the CBP molecule. In this work, by means of quantum chemical methods the behavior of substrates in these proteins is analyzed. It is shown that coelenterazine can form different tautomers: CLZ(2H) and CLZ(7H). The formation of 2-hydroperoxy-coelenterazine is studied. According to the obtained data, these proteins use different forms of the substrates for the reaction. In obelin, the substrate is in the CLZ(2H) form that affords hydrogen peroxide. In RM, coelenterazine is in the CLZ(7H) form, and therefore, CBP is not activated by oxygen.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Antonova A. B., Chudin O. S., Vasiliev A. D., Rubaylo A. I., Verpekin V. V., Sokolenko W. A., Pavlenko N. I., Semeikin O. V.
Заглавие : Chemistry of vinylidene complexes. XX. Intramolecular carbonylation of vinylidene on the MnFe center: Spectroscopic and structural study. X-ray structure of the new trimethylenemethane type MnFe complex
Место публикации : J. Organomet. Chem.: Elsevier, 2011. - Vol. 696, Is. 4. - P.963-970. - ISSN 0022-328X, DOI 10.1016/j.jorganchem.2010.10.035
Примечания : Cited References: 52. - This work was partially supported by the Presidium of the Russian Academy of Sciences (Program for Basic Research, Project No. 7.18) and Russian Foundation for Basic Research (Grant No. 09-03-90745-mob_st). Authors are grateful to Prof. N.A. Ustynyuk for useful discussions, Dr. E.A. Shor and Dr. A.M. Shor for giving the data of quantum chemical study.
Предметные рубрики: MOLECULAR-STRUCTURE
ORGANOMETALLIC CHEMISTRY
TRICARBONYL COMPLEXES
UNSATURATED CARBENES
METAL VINYLIDENES
TRANSITION-METALS
ORGANIC-SYNTHESIS
CRYSTAL-STRUCTURE
IRON TRICARBONYL
MANGANESE
Ключевые слова (''Своб.индексиров.''): manganese--iron--carbonyl complexes--heteronuclear vinylidene complexes--intramolecular vinylidene carbonylation--trimethylenemethane complexes
Аннотация: Reactions of Fe-2(CO)(9) with Cp(CO)(2)Mn=C=CHPh (1) and Cp(CO)(PPh3)Mn=C=CHPh (3) gave the heterometallic trimethylenemethane complexes eta(4)-{C[Mn(CO)(2)Cp](CO)CHPh}Fe(CO)(3) (2) and eta(4)-{C[Mn(CO)(PPh3)Cp](CO)CHPh}Fe(CO)(3) (4), respectively. The formation of the benzylideneketene [PhHC=C=C=O] fragment included in complexes 2 and 4 occurs via intramolecular coupling of the carbonyl and vinylidene ligands. The structures of 3 and 4 were determined by single crystal XRD methods. The influence of the nature of the L ligands at the Mn atom on the structural and spectroscopic characteristics of eta(4)-{C[Mn(CO)(L)Cp](CO)CHPh}Fe(CO)(3) (L = CO (2), PPh3 (4)) is considered. According to the VT H-1 and C-13 NMR spectra, complex 2 reversibly transforms in solution into mu-eta(1):eta(1)-vinylidene isomer Cp(CO)(2)MnFe(mu-C=CHPh)(CO)(4) (2a), whereas complex 4 containing the PPh3 ligand is not able to a similar transformation. (C) 2010 Elsevier B.V. All rights reserved.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Isaenko L. I., Kesler V. G., Kang L., Lin Z. S., Molokeev M. S., Yelisseyev A. P., Zhurkov S. A.
Заглавие : Structural, spectroscopic, and electronic properties of cubic G0-Rb2KTiOF5 oxyfluoride
Место публикации : J. Phys. Chem. C: American Chemical Society, 2013. - Vol. 117, Is. 14. - P.7269-7278. - ISSN 1932-7447, DOI 10.1021/jp401391y
Примечания : Cited References: 80. - This study was supported by SB RAS (Grant 28.13), the National Natural Science Foundation of China under Grants 11174297 and 91022036, and the National Basic Research Project of China (Nos. 2010CB630701 and 2011CB922204).
Предметные рубрики: RAY PHOTOELECTRON-SPECTROSCOPY
SURFACE CHEMICAL-STABILITY
EFFECTIVE IONIC-RADII
PHASE-TRANSITIONS
CRYSTAL-GROWTH
HEAT-CAPACITY
CORE LEVELS
RB2KTIOF5
FLUORIDES
OXIDES
Аннотация: The G0-Rb2KTiOF5 single crystals with dimensions up to nearly a centimeter in size have been prepared by slow solidification method. The elpasolite-related crystal structure of G0-Rb2KTiOF5 has been refined by Rietveld method at T = 298 K (space group Fm (3) over barm, Z = 4, a = 8.880(1) angstrom, V = 700.16(2) angstrom(3); R-B = 2.66%). The wide optical transparency range of 0.25-9 mu m and forbidden band gap of E-g = 3.87 eV have been obtained for the G0-Rb2KTiOF5 crystal. Dominating photoluminescence bands at 3.36 and 2.33 eV are related to free and self-trapped excitons, respectively. The electronic structure of G0-Rb2KTiOF5 has been evaluated by X-ray photoelectron spectroscopy and calculated with the first-principles methods. A good agreement between theoretical and experimental results has been achieved. Chemical bonding effects have been discussed for all metal ions using binding energy difference parameters and a wide comparison with related oxides and fluorides. The competition between O2- and F- ions for metal valence electrons has been found.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Atuchin V. V., Molokeev M. S., Yurkin G. Yu., Gavrilova T. A., Kesler V. G., Laptash N. M., Flerov I. N., Patrin G. S.
Заглавие : Synthesis, structural, magnetic, and electronic properties of cubic CsMnMoO3F3 oxyfluoride
Место публикации : J. Phys. Chem. C: American Chemical Society, 2012. - Vol. 116, Is. 18. - P.10162-10170. - ISSN 1932-7447, DOI 10.1021/jp302020f
Примечания : Cited References: 64. - We thank Dr. A.M. Ziatdinov for the electron paramagnetic resonance measurements. This study was partly supported by SB RAS (Grant 28).
Предметные рубрики: RAY PHOTOELECTRON-SPECTROSCOPY
PHASE-TRANSITIONS
CORE LEVELS
SURFACE CHARACTERIZATION
CRYSTAL-STRUCTURE
CLEAVED SURFACE
MIXED-VALENCE
OXIDES
MN
MOLYBDENUM
Chemical bondings
Cubic phase
Energy differences
Heat capacity measurements
Oxyfluorides
Powder samples
Solid-state synthesis
Space Groups
Temperature range
Valence electron
Binding energy
Chemical bonds
Electronic structure
Fluorine compounds
Magnetic properties
Metal ions
Photoelectrons
Rietveld method
X ray photoelectron spectroscopy
Electronic properties
Аннотация: A powder sample of CsMnMoO3F3 oxyfluoride has been prepared by solid state synthesis. The pyrochlore-related crystal structure of CsMnMoO3F3 has been refined by the Rietveld method at T = 298 K (space group Fd-3m, a = 10.59141(4) angstrom, V = 1188.123(8) angstrom(3); R-B = 3.44%). The stability of the cubic phase has been obtained over the temperature range T = 110-293 K by heat capacity measurements. Magnetic properties have been measured over the range of T = 2-300 K. The electronic structure of CsMnMoO3F3 has been evaluated by X-ray photoelectron spectroscopy. Chemical bonding effects have been discussed for all metal ions using binding energy difference parameters and wide comparison with related oxides and fluorides. The competition between O-2(-) and F- ions for metal valence electrons has been found.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S.
Заглавие : Crystal structure of catena-Bis(2-thiobarbiturato-O,S)diaquacadmium
Место публикации : Russ. J. Inorg. Chem.: Springer, 2013. - Vol. 58, Is. 10. - P.1193-1196. - DOI 10.1134/S0036023613100094
Аннотация: The crystal structure of catena-bis(2-thiobarbiturato-O,S)diaquacadmium (C8H10CdN4O6S2) n (I), [Cd(H2O)2(HTBA)2] n (C4H4N2O2S is 2-thiobarbituric acid, H2TBA) has been determined. The crystals of compound I are triclinic, a = 6.9433(3) Å, b = 7.2257(3) Å, c = 7.4047(3) Å, α = 88.559(2)°, β = 75.346(2)°, γ = 111.687(1)°, V = 331.05(3) Å3, space group P1¯ , Z = 1. The Cd2+ ion is coordinated to the two oxygen atoms of water molecules and the two oxygen and two sulfur atoms of four HTBA− ions at the vertices of an octahedron. Octahedra are linked by bridging μ2-HTBA−-O,S ions into infinite chains. Intermolecular hydrogen bonds form infinite chains. The structure is also stabilized by the π-π interaction of HTBA− ions.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Golovnev N. N., Molokeev M. S., Golovneva I. I., Glushchenko G. A.
Заглавие : Crystal structure of enrofloxacinium tetrabromidodichloridostannate(IV) monohydrate
Место публикации : J. Struct. Chem.: SPRINGER, 2013. - Vol. 54, Is. 2. - P.377-382. - ISSN 0022-4766, DOI 10.1134/S0022476613020157
Примечания : Cited References: 17. - The work was supported by the grant of the President of the Russian Federation for the support of leading scientific schools of the Russian Federation (NSh-4828.2012.2) and the Federal Targeted Program "Scientific and Scientific Pedagogical Personnel of Innovative Russia, 2009-2013" (State contracts Nos. 02.740.11.0269 and 02.740.11.0629).
Предметные рубрики: COMPLEX
Ключевые слова (''Своб.индексиров.''): crystal structure--enrofloxacinium cation--tetrabromidodichloridostannate(iv) anion--hydrogen bonds
Аннотация: A new compound EnrH(3)[SnBr3.46Cl2.54]center dot H2O, where EnrH (3) (2+) is the enrofloxacinium cation (C19H24FN3O (3) (2+) ), is synthesized and its crystal and molecular structure is determined. Crystallographic data for enrofloxacinium tetrabromidodichloridostannate(IV) monohydrate are as follows: a = 17.1262(19) , b = 10.3435(11) , c = 17.2582(19) , beta = 119.203(1)A degrees, V = 2640.5(4) (3), space group P2(1)/c, Z = 4. Hydrogen bonds form a branched three-dimensional network linking EnrH (3) (2+) , [SnBr3.46Cl2.54](2-), and water molecules. The structure is also stabilized by the pi-pi interaction of EnrH (3) (2+) aromatic rings.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xia, Zhiguo, Zhang Y., Molokeev M. S., Atuchin V. V.
Заглавие : Structural and luminescence properties of yellow-emitting NaScSi 2O6:Eu2+ phosphors: Eu2+ Site preference analysis and generation of red emission by codoping Mn2+ for white-light-emitting diode applications
Место публикации : J. Phys. Chem. C: American Chemical Society, 2013. - Vol. 117, Is. 40. - P.20847-20854. - DOI 10.1021/jp4062225
Примечания : Cover image: Artwork representing main idea of this article
Аннотация: The structural properties of clinopyroxene NaScSi2O6 have been investigated using the X-ray powder diffraction refinement, and the luminescence properties of Eu2+ and Eu2+/Mn 2+-activated NaScSi2O6 have been studied to explore the new materials for phosphor-converted white light ultraviolet light-emitting diodes (UV-LEDs). Eu2+ was introduced into the NaScSi2O6 host in the reducing atmosphere, and the preferred crystallographic positions of the Eu2+ ions were determined based on the different structural models of the NaScSi2O6 host. The as-obtained NaScSi2O6:Eu2+ phosphor shows greenish yellow emission with the broad-band peak at 533 nm, and efficient energy transfer (ET) takes place between Eu2+ and Mn2+ in NaScSi2O6, leading to a series of color-tunable phosphors emitting at 533 and 654 nm for the designed NaScSi2O 6:Eu2+,Mn2+ phosphors under excitation at 365 nm. The ET mechanism of Eu2+ and Mn2+ has also been evaluated. We have demonstrated that NaScSi2O6:Eu 2+ and NaScSi2O6:Eu2+,Mn 2+ materials exhibit great potential to act as the effective phosphors for UV-LEDs. В© 2013 American Chemical Society.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fokina V. D., Gorev M. V., Bogdanov E. V., Pogoreltsev E. I., Flerov I. N., Laptash N. M.
Заглавие : Thermal properties and phase transitions in (NH4) 3ZrF7
Место публикации : Journal of Fluorine Chemistry. - 2013. - Vol. 154. - P.1-6. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2013.07.001
Ключевые слова (''Своб.индексиров.''): cubic fluorides--entropy--permittivity--phase transitions--pressure effect--thermal dilatation
Аннотация: The heat capacity, thermal dilatation, permittivity, and T-p phase diagram of (NH4)3ZrF7 have been studied in wide temperature and pressure ranges. Two phase transitions were found in addition to previously known structural transformations. The stability of crystal phases to temperature and pressure has been examined and a possibility of transition between two cubic phases has been discussed. The total excess entropy change SDSi = Rln6 is characteristic for the order-disorder processes, but its stepwise increase is not consistent with the structural model associated with the strong disorder assumed in the initial cubic phase. В© 2013 Elsevier B.V. All rights reserved.
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20.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Flerov I. N., Pogoreltsev E. I., Mel'nikova S. V., Gorev M. V., Kartashev A. V., Bogdanov E. V., Molokeev M. S., Laptash N. M.
Заглавие : Structure, physical properties and phase transitions in (NH4)2TiF6×NH4F
Коллективы : European Symposium on Fluorine Chemistry (17; 2013 ; June ; 21-25; Paris, France)
Место публикации : 17th European Symposium on Fluorine Chemistry: Abstracts book. - 2013. - P.37
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