A. M. Ob”edkov

Stoichiometric synthesis of fullerene compounds with lithium and sodium and analysis of their IR and EPR spectra

A modified method is proposed for preparing fullerene compounds with alkali metals in a solution. The compounds synthesized have the general formula MenC60(THF)x, where Me = Li or Na; n=1–4, 6, 8, or 12; and THF = tetrahydrofuran. The use of preliminarily synthesized additives MeC10H8 makes it possible to prepare fullerene compounds with an exact stoichiometric ratio between C60n− and Me+. The IR and EPR spectra of the compounds prepared are analyzed and compared with the spectra of their analogs available in the literature. The intramolecular modes Tu(1)-Tu(4) for the C60n− anion are assigned. The splitting of the Tu(1) mode into a doublet at room temperature for MenC60(THF)x (n=1, 2, 4) compounds indicates that the fullerene anion has a distorted structure. An increase in the intensity of the Tu(2) mode, a noticeable shift of the Tu(4) mode toward the long-wavelength range, and an anomalous increase in the intensity of the latter mode for the Li3C60(THF)x complex suggest that, in the fullerene anion, the coupling of vibrational modes occurs through the charge-phonon mechanism. The measured EPR spectra of lithium-and sodium-containing fullerene compounds are characteristic of C60− anions. The g factors for these compounds are almost identical and do not depend on temperature. The g factor for the C60n− anion depends on the nature of the metal and differs from the g factor for the C60− anion.

Effect of the catalytic system based on multi-walled carbon nanotubes modified with copper nanoparticles on the kinetics of catalytic reduction of germanium tetrachloride by hydrogen

Effect of a catalyst based on multi-walled carbon nanotubes modified with copper nanoparticles on the kinetics of the catalytic reduction of germanium tetrachloride by hydrogen was studied in the temperature range 423–723 K. Results of experiments were used to determine the reaction order and activation energy. A mechanism of the occurring reaction is suggested on the basis of the data obtained. The introduction of catalysts based on multi-walled carbon nanotubes modified with copper nanoparticles made it possible to lower the reaction temperature and achieve a germanium tetrachloride conversion of about 98%.

Study of carbon nanostructures obtained by pyrolytic synthesis

The structure and phase composition of a carbon nanomaterial obtained by the thermal decomposition of toluene-ferrocene mixtures are studied by Mössbauer spectroscopy, high-resolution electron microscopy, and x-ray diffraction. Variations in the structural state of the catalyst and in the quantitative yield of the nanomaterial are analyzed as functions of the synthesis time.

Interaction of sodium fullerene derivatives with trimethylchlorosilane

AbstractSoluble dimer compounds of the general formula [C60(Me3Si)n]2 (where n = 3, 5, 7, or 9 and Me = CH3) and a soluble monomer compound, C60(Me3Si)12, are synthesized by the reaction of the compound C60Nan(THF)x (where n = 4, 6, 8, 10, or 12 and THF = tetrahydrofuran) with trimethylchlorosilane Me3SiCl. The compounds synthesized are identified using IR and NMR spectroscopy and mass spectrometry. An irreversible endothermic effect exhibited by the [C60(Me3Si)7]2 compound in the temperature range 448–570 K is revealed by dynamic adiabatic calorimetry. From analyzing the experimental results, it becomes possible for the first time to demonstrate the structural flexibility of the fullerene in the following sequence of reactions:

MOCVD modification of the surface of multiwalled carbon nanotubes to impart to them necessary physicochemical properties

\begin{array}{*{20}c} {C_{60} \xrightarrow[{ - 12C_{10} H_8 }]{{ + 12NaC_{10} H_8 }}C_{60} Na_{12} \xrightarrow[{ - 12NaCl}]{{ + excess Me_3 SiCl}}C_{60} (Me_3 Si)_{12} \xrightarrow[{ - 12Me_3 SiCl}]{{ + HCl(gas)}}[C_{60} H_n ]\xrightarrow[{ - 1/2nH_2 }]{{hv}}C_{60} } \\ {C_{60} \xrightarrow[{ - 8C_{10} H_8 }]{{ + 8NaC_{10} H_8 }}C_{60} Na_8 \xrightarrow[{ - 8NaCl}]{{ + excess Me_3 SiCl}}[C_{60} (Me_3 Si)_7 ]_2 \xrightarrow{{573K}}\begin{array}{*{20}c} {products of the} \\ {transformation of + } \\ {Me_3 Si groups} \\ \end{array} C_{60^ - } } \\ \end{array}

Deposition of nanocrystalline nonstoichiometric chromium oxide coatings on the surface of multiwalled carbon nanotubes by chromium acetylacetonate vapor pyrolysis

Pyrolytic tungsten coatings have been produced on the surface of ash microspheres under steady-state conditions using tungsten hexacarbonyl as a precursor. The nanostructured composites thus obtained were characterized by X-ray diffraction and scanning electron microscopy. We have studied the kinetics of the catalytic reduction of germanium tetrachloride with hydrogen in the temperature range 423–973 K in the presence of the composites as catalysts and determined the reaction order and activation energy for the catalytic reduction of germanium tetrachloride with hydrogen.

Reduction of GeCl4 in the presence of a catalyst based on modified NiCl2

Multiwalled iron-containing carbon nanotubes were synthesized by the MOCVD method with pyrolysis of ferrocene and toluene mixtures in an argon flow at atmospheric pressure. Using the MOCVD method with vacuum pyrolysis of bis-arene-chromium compounds onto the surface of multiwalled carbon nanotubes (MWCNTs), pyrolytic chromium films were deposited and new composite materials MWCNT/pyrolytic chromium were obtained. The composite morphology depends on the conditions of pyrolytic chromium deposition. Regular bead-shaped structures were detected. The mechanism of their appearance due to the formation of bis-arene chromium compounds of the intermediate viscoplastic polymer phase and the onset of Plateau-Rayleigh instability during pyrolysis is discussed.