Papers by Aleksandr Shubin
Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 1986
J. Chem. SOC., Faraday Trans. I , 1986, 82, 1879-1884 ... High-resolution Solid-state Magic Angle... more J. Chem. SOC., Faraday Trans. I , 1986, 82, 1879-1884 ... High-resolution Solid-state Magic Angle Spinning Nuclear Magnetic Resonance Investigations of Surface Hydroxy Groups on Modified Silica Gel ... Thomas Bernstein* Karl-Marx-Universitat, Sektion Physik, DDR-7010 ...
Russ Chem Bull, 1988
ABSTRACT Water molecules in partially dehydrated zeolite directly interact with Na+ cations. The ... more ABSTRACT Water molecules in partially dehydrated zeolite directly interact with Na+ cations. The final three or four water molecules per unit cell removed upon the dehydration of zeolite are apparently bound to Na+ cations of the eight-membered windows, while the previous ~10 molecules are bound to Na+ cations of six-membered windows.
Chemical Physics Letters, 2015
Journal of Magnetic Resonance (1969), 1985
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The Journal of Physical Chemistry C, 2016
Journal of Magnetic Resonance (1969), 1983
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Journal of Magnetic Resonance (1969), 1981
expressions for the modulation effects in two-and three-pulse electron spin echoes resulting from... more expressions for the modulation effects in two-and three-pulse electron spin echoes resulting from the hyperfine interaction of an electron and a nucleus with an arbitrary spin are derived. The two-pulse envelope modulation is calculated numerically for some nuclei for which modulation effects are most often observed experimentally.
Theoretical and Experimental Chemistry, 2006
ABSTRACT A heterogeneous catalyst for the hydrochlorination of acetylene by gaseous HCl is formed... more ABSTRACT A heterogeneous catalyst for the hydrochlorination of acetylene by gaseous HCl is formed as a result of mechanical treatment of the solid salt K2PtCl4 in an atmosphere of acetylene, ethylene, or propylene by the formation of π complexes of platinum(II) as active centers in the surface layer under these conditions. The controlling stage of the catalytic reaction is chloroplatination of the π-coordinated acetylene by the HCl molecule. The reaction takes place as a concerted process, in which an intermediate β-chlorovinyl derivative of platinum(II), a complex of platinum with a coordination vacancy[PtCl 3 * ]−, and a new molecule of HCl are formed simultaneously with cleavage of the H—Cl and Pt—Cl bonds in the metal complex adjacent to the π-acetylene complex. The catalytic cycle closes with rapid dissociation of the organoplatinum intermediate by the action of HCl, giving the final product and the initial complex [PtCl4]2−.
ChemInform, 1999
ABSTRACT Milling of V2O5 in a ball mill increased the surface area from 7 to a maximum of 32 m2/g... more ABSTRACT Milling of V2O5 in a ball mill increased the surface area from 7 to a maximum of 32 m2/g. Simultaneously, XRD line broadening suggested a reduction of the microcrystallites. A color change during milling indicated oxygen loss, and Raman spectroscopy provided evidence for the formation of shear structures such as V6O13. The number of V4+ ions produced was determined by ESR spectroscopy and that of V3+ ions was obtained from magnetic susceptibility measurements. The local environment of the vanadium nucleus in V2O5 after milling in a ball mill was characterized by the combination of static (wide line) and MAS 51V NMR techniques together with theoretical simulations of NMR spectra. Important information on the quadrupole and chemical shielding tensors, including the relative tensor orientation and the distribution of magnetic resonance parameters, is discussed for the vanadium nucleus in V2O5 after milling. Special attention was given to the formation of paramagnetic V3+ and V4+ ions and their influence on 51V NMR spectra of diamagnetic V5+ in milled samples. It was shown that paramagnetic V3+ ions are responsible for the loss (up to about 70%) of the intensity in 51V NMR spectra. The influence of other V4+ paramagnetic ions is significantly smaller.
The Journal of Physical Chemistry C, 2015
Russian Journal of Inorganic Chemistry
Stabilization of Cu2+ ions in concentrated aqueous ammonia solutions of copper nitrate in a wide ... more Stabilization of Cu2+ ions in concentrated aqueous ammonia solutions of copper nitrate in a wide range of ammonium ion concentrations has been studied by EPR and electronic absorption spectroscopy. Three types of Cu2+ associates with different types of orbital ordering have been identified. The ammonium ion concentration in a solution has a decisive effect on the type of orbital ordering of Cu2+ ions in associates. In all cases, Cu2+ ordering in associates is caused by the existence of bridging OH groups in the axial and equatorial positions of [Cu(NH3)n (H2O)6 − n ]2+ complexes (n < 6). At a high concentration of ammonium ions, weakly bound associates of tetramminecopper with the $d_{x^2 - y^2 }$ ground state are formed. In solutions with low ammonium concentrations, bulky associates with the $d_{y^2 }$ and $d_{x^2 - z^2 }$ ground states and associates of Cu2+ ions with the $d_{x^2 - y^2 }$ ground state with hydroxyl groups in the equatorial plane and axial water molecules are f...
Journal of Molecular Catalysis, 1990
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Reaction Kinetics and Catalysis Letters, 1986
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Chemical Physics Letters, 2015
ABSTRACT The formation of the O-O bond in the water oxidation catalyzed by the iron hydroxides wa... more ABSTRACT The formation of the O-O bond in the water oxidation catalyzed by the iron hydroxides was modeled with the Fe4O4(OH)(4) and Fe2O2(OH)(4) complexes by means of the density functional theory. Consideration of the local minima and transition states for various routes of the association of oxo- and hydroxo-centers reveals a determinative role of the oxyl radical center Fe-III-O center dot- in facilitating this process. The preferable scenario comprises two steps: (1) the abstraction of the electron and proton from the initial complex leaving behind a ferryl FeO group, and (2) the incorporation of ferryl oxygen into the tetramer edge to form peroxo group.
ChemInform, 1999
1999 magnetic resonance, nuclear quadrupole resonance magnetic resonance, nuclear quadrupole reso... more 1999 magnetic resonance, nuclear quadrupole resonance magnetic resonance, nuclear quadrupole resonance (solids and liquids) D 6560 50 -017 Characterization of V 2 O 5 -TiO 2 Catalysts by Milling by ESR and Solid State 1 H and 51 V NMR. -Milling of V 2 O 5 /TiO 2 mixtures induces spreading of vanadia across the titania surface, whereby two types of V 5+ species strongly bonded to titania are formed. In addition, V 3+ centers and at least three structurally different V 4+ centers are detected. -(LAPINA, OLGA B.; SHUBIN, ALEXANDER A.; NOSOV, ANDREI V.; BOSCH, ERIC; SPENGLER, JOERG; KNOEZINGER, HELMUT; J. Phys. Chem. B 103 (1999) 36, 7599-7606; Inst. Phys. Chem.,
Theoretical and Experimental Chemistry, 2006
The hydrochlorination of acetylene by gaseous HCl is catalyzed at room temperature on the surface... more The hydrochlorination of acetylene by gaseous HCl is catalyzed at room temperature on the surface of dry K 2 PtCl 4 subjected to mechanical preactivation in an acetylene atmosphere. The acetylene hydrochlorination product is formed by trans addition. The kinetic isotope effect (KIE) upon replacing HCl by DCl is 5 ± 1, which is much greater than the KIE found in the catalytic hydrochlorination of acetylene on the surface of mechanically preactivated K 2 PtCl 6 (1.9). This discrepancy suggests different reaction mechanisms in these two systems.
ChemInform, 2006
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
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Papers by Aleksandr Shubin