V. M. Senyavin

Vanadium peroxocomplexes as oxidation catalysts of sulfur organic compounds by hydrogen peroxide in bi-phase systems

Abstract New vanadium oxodiperoxocomplexes Bu4N+[VO(O2)2 L2]− were synthesized, where L=pyridine (1), 2-methylpyridine (2), 4-methylpyridine (3), 2-oxymethylpyridine (4). All complexes were characterized by NMR ( 1 H , 51 V ) and IR spectroscopy. The oxidation of sulfur organic compounds and diesel fuel desulfurization catalyzed by vanadium peroxocomplexes in bi-phase system was investigated in various solvents. The complexes manifested high catalytic activity and selectivity in oxidation of sulfides.

Pressure-induced dimerization of fullerene C60: a kinetic study

Abstract The kinetics of pressure-induced dimerization of fullerite C60 at 1.5 GPa in the 373–473 K temperature interval was studied by X-ray diffraction, infrared and Raman spectroscopy. Kinetic curves of the dimerization reaction in the fcc and sc phases of C60 were obtained by monitoring the dimeric (C60)2 IR line at 796 cm−1. The value of the dimerization activation energy was determined to be E a ( dim ) =134±6 kJ mol −1 , assuming the second order irreversible reaction. The peculiarities of the dimerization processes in the fcc and sc phases of C60 fullerite are also discussed.

Sublimation of hydrofullerenes C60H36 and C60H18

Abstract Thermal behavior of two hydrofullerenes, C 60 H 36 and C 60 H 18 , was studied by means of Knudsen cell mass-spectrometry and infrared spectroscopy. Vapor pressures and enthalpies of sublimation at T =550–685 K were measured. Sublimation of the hydrofullerenes was accompanied by partial loss of hydrogen. Decomposition of C 60 H 36 was confirmed to be a stepwise process with formation of C 60 H 18 as an intermediate product. The material of the Knudsen cell strongly affected the partial pressures and mass-spectra of the hydrofullerene vapor species.

Synthesis and structure of oxovanadium(IV) complexes [VO(Acac)(2)] and [VO(Sal : L-alanine)(H2O)]

AbstractBis(acetylacetonato)oxovanadium C10H14O5V (I) and (S)-[2-(N-salicylidene)aminopropionate]oxovanadium monohydrate C10H9NO5V (II) are synthesized. The crystal structures of compounds I and II are determined using single-crystal X-ray diffraction. Crystals of compound I are triclinic, a = 7.4997(19) Å, b = 8.2015(15) Å, c = 11.339(3) Å, α = 91.37(2)°, β = 110.36(2)°, γ = 113.33(2)°, Z = 2, and space group

Pressure-induced dimerization of C60 fullerene

P\bar 1

Vibrational Spectra of Chloro‐ and Bromofullerenes

. Crystals of compound II are monoclinic, a = 8.5106(16) Å, b = 7.373(2) Å, c = 9.1941(16) Å, β = 101.88(1)°, Z = 2, and space group P21. The structures of compounds I and II are solved by direct methods and refined to R1 = 0.0382 and 0.0386, respectively. The oxovanadium complexes synthesized are investigated by vibrational spectroscopy.

Synthesis and properties of nanosilicon prepared by homogeneous and heterogeneous reduction of tetraethyl orthosilicate

RATIONALE Ionic liquids ([Cat(+)][An(-)]) were believed to decompose before reaching vaporization temperatures, but recently some of them have been shown to vaporize congruently. Low-temperature vaporization of ionic substances is an intriguing phenomenon, so the vapor-phase composition and reactions of ionic liquids deserve more extensive study. METHODS Evaporation of two ionic liquids, [C2MIM(+)][Tf2 N(-)] and [C3MMIM(+)][Tf2N(-)], was studied by means of Knudsen effusion mass spectrometry. These liquids were also characterized using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, UV/Vis, IR, NMR spectroscopy, and elemental analysis. RESULTS The vaporization enthalpies of (118 ± 3) and (124 ± 2) kJ·mol(-1) were determined for [C2MIM(+)][Tf2N(-)] and [C3MMIM(+)][Tf2N(-)], respectively. The corresponding equations for their saturated vapor pressures are: ln(p{[C2MIM(+)][Tf2N(-)]}/Pa) = -(14213 ± 325)/(T/K) + (26.57 ± 1.04), ln(p{[C2MMIM(+)][Tf2N(-)]}/Pa) = -(14868 ± 221)/(T/K) + (27.19 ± 0.60). The MALDI studies (positive and negative ion modes) enabled detection of monomeric [Cat(+)] and [An(-)] ions, the cluster ions {[Cat(+)]2 [An(-)]}(+) and {[Cat(+)][An(-)]2}(-), and some complex anions {2[An(-)] + Na(+)}(-), {2[An(-)] + K(+)}(-), {2[An(-)] + Cu(+)}(-) and {3[An(-)] + Ca(2+)}(-). CONCLUSIONS Knudsen effusion mass spectrometry proved to be a valuable method to study the thermodynamics of ionic liquids. The saturated vapor pressure and vaporization enthalpy of [C3MMIM(+)][Tf2N(-)] were accurately determined for the first time. MALDI is also capable of providing indirect information on hydrogen bonding.

Equilibrium Phase Diagram of Polymerized C60 and Kinetics of Decomposition of the Polymerized Phases

The dimerization of C60 fullerene under conditions of quasi-hydrostatic compression at temperatures above 293 K is investigated by IR spectroscopy, Raman scattering (RS) spectroscopy, and x-ray diffraction. The measured dimer (C60)2 content in the products of the polymerization of fullerite as a function of the pressure, temperature, and treatment time shows that dimerization occurs even at room temperature in the entire pressure range above ∼1.0 GPa. However, at least at temperatures above 400 K dimerization does not result in the formation of a dimer phase as a stable modification of the system, since the dimer is an intermediate product of the transformation. It is shown that increasing the holding time at 423 K decreases the content of the dimer fraction in the samples and results in the formation of linear (at 1.5 GPa) and two-dimensional (at 6.0 GPa) polymers, which are structure-forming elements of the orthorhombic and rhombohedral polymerized phases.