Calculation of adsorption heats of nitric oxide on ruthenium by the bond interaction method

Chemisorption heats of nitric oxide on Ru(0001) and Ru(1010) planes have been calculated by the bond interaction method. It is shown that the calculated values correlate well with TPD data.

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(000I) (I0I0) . , .

     

Pressure effects on oxygen interaction with ruthenium catalysts

Statistical adsorption and TPD studies of P_{O 2}=1.33 and 90,440 Pa and T_ads=163–523 K have revealed that Ru oxidation at high pressures begins already at T_ads=300 K, while at low ones it starts at 353 K. Temperature increase leads to its surface oxidation at low pressures (1.33 Pa) and to the deep oxidation with the formation of stoichiometric oxides at high pressures (90,4440 Pa).

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P_{O 2}=1,33 90440 163–523 . , Ru =300 , - 353 . Ru (1,33 ), (90440 ) .

     

Calculation of molecular energy indices by the bond interaction method

Conclusions Parameters were determined for an interacting bond model for hydrocarbons and oxygen- and sulfur-containing organic molecules. The parameters obtained were used to calculate the homolytic bond dissociation energies and molecular formation energies.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1680–1683, July, 1988.     

Energy studies of atomic atmospheric ions in collisions with molecular nitrogen and oxygen

Studies of internal energy changes between the partners in ion-molecule collisions can be facilitated by high-resolution translational energy spectroscopy. Collisions of keV H⁺, N⁺ and O⁺ on molecular nitrogen and oxygen have shown that for 30 reaction channels all are consistent with spin conservation, which has not been generally acknowledged in previous studies. Estimations of the fractional metastable composition in each ion beam have also been made.     

The interaction of iron pyrite with oxygen, nitrogen and nitrogen oxides: a first-principles study

Sulphide materials, in particular MoS(2), have recently received great attention from the surface science community due to their extraordinary catalytic properties. Interestingly, the chemical activity of iron pyrite (FeS(2)) (the most common sulphide mineral on Earth), and in particular its potential for catalytic applications, has not been investigated so thoroughly. In this study, we use density functional theory (DFT) to investigate the surface interactions of fundamental atmospheric components such as oxygen and nitrogen, and we have explored the adsorption and dissociation of nitrogen monoxide (NO) and nitrogen dioxide (NO(2)) on the FeS(2)(100) surface. Our results show that both those environmentally important NO(x) species chemisorb on the surface Fe sites, while the S sites are basically unreactive for all the molecular species considered in this study and even prevent NO(2) adsorption onto one of the non-equivalent Fe-Fe bridge sites of the (1 × 1)-FeS(2)(100) surface. From the calculated high barrier for NO and NO(2) direct dissociation on this surface, we can deduce that both nitrogen oxides species are adsorbed molecularly on pyrite surfaces.     

Reactions of atomic nitrogen and atomic hydrogen with methylacetylene

The reaction of nitrogen atoms with methylacetylene has been studied using a fast-flow low-pressure reactor coupled to a mass spctrometer by a nozzle-beam sampling system. Hydrogen atom concentrations were measured by ESR analysis. Experimental second-order rate constants for the consumption of N atoms, of C₃H₄, and for the formation of N₂ were determined in the temperature range of 283° to 485°K. Product profiles of all stable species and of hydrogen atoms and methyl radicals were obtained for different initial concentrations of the reactants. Two different reaction pathways can be distinguished: one provides for recombination of N atoms, and the second leads to the formation of cyano compounds and other hydrocarbons. Only the latter process is influenced by the addition of hydrogen atoms. Mechanisms for the two pathways are discussed.     

A method for the quantitative decomposition of cluster compounds and the determination of rhodium and ruthenium by flame atomic absorption spectrometry

Summary Single crystals of cluster compounds were decomposed with two different methods. The hydrogen peroxide method is easy to use and no special equipments are needed. The autoclave method has proved to be more effective and led to the complete decomposition of all tested cluster compounds. Buffering with lanthanum sulphate or KHSO₄ was used to eliminate interferences caused by foreign metal ions and phosphorus. Results of measurements after decomposition of the cluster compounds with the two methods are shown.

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Quantitative Aufspaltung von Clusterverbindungen und Bestimmung von Rhodium und Ruthenium durch Flammen-AAS

     

钌(Ⅱ)卟啉催化含氮芳杂环的酰亚胺化

目前,N-N键形成的方法尽管有:催化胺化[1],利用叠氮化合物[2,3],氯氨-T法[4],亚硝化-还原,羟胺氧磺酸等方法。这些方法都各有千秋,互相补充。但我们为合成目标化合物在尝试这些方法时,仅过渡金属配合物Ru(TTP)(CO)催化胺化法得到较为理想结果。加之近年来卟啉配合物催化形成C-N键已成为获得某些天然产物和生物活性分子的具有吸引力的方法之一[5-13]。我们希望利用Ru(TTP)(CO)催化的氮宾插入反应在含sp2N的杂环N上直接引入磺酰亚胺,为我们进一步获得新的生物活性化合物以及进行体外筛选提供可能。也为合成一些具有生物活性化合物开辟…     

Measurement of the dispersity of supported ruthenium catalysts by oxygen chemisorption

A highly dispersed (Ø (Ru)<10 Å, from electron microscopy) Al₂O₃-supported catalyst and not so well dispersed silica supported Pt, Ru, Pt, Ru-alloy catalysts were investigated. Oxygen coverage of Ru is found to be close to 2 at 20 °C over the monometallic Ru catalysts as well as over the Pt, Ru-alloy catalysts.

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(Ø (Ru)<10 Å ) Al₂O₃ Pt Ru Pt Ru . Ru 2 20°C Ru, Pt Ru.

     

Study of the interaction between oxygen and bile salts

The interaction between molecular oxygen and bile salts, previously observed using chemiluminescence techniques, is studied in this paper by electrochemical techniques to further highlight the nature of the interaction. A shift of half-wave potential of the first polarographic wave for the reduction of molecular oxygen was observed in solutions in the presence of bile salts. The shift could be related to different phenomena, such as adsorption of bile salt molecules on the mercury electrode, irreversibility of the oxygen reduction reaction, pH of the solution. Experimental results suggest the exclusion of the above mentioned processes and outline the occurrence of a direct interaction between oxygen and bile salts, where the hydrophobic face of bile salt monomers and/or small aggregates are involved, enhancing so dismutation of superoxide ion produced at the electrode. The presence of bile salts in solutions containing triphenylphosphine oxide, a hydrophobic surfactant, increases also the wave of reduction of molecular oxygen. As a consequence bile salts, beside the well-assessed physiological roles, can behave as oxygen carrier and as antioxidant, preventing the oxidation of biological compounds by superoxide ion.     

Reaction of atomic oxygen with cyclopentadiene

The reaction of 1,3-cyclopentadiene (CPD) with ground-state atomic oxygen O(³P), produced by mercury photosensitized decomposition of nitrous oxide, was studied. The identified products were carbon monoxide and the following C₄H₆ isomers: 3-methylcyclopropene, 1,3-butadiene, 1,2-butadiene, and 1-butyne. The yield of carbon monoxide over oxygen atoms produced (?_CO) was equal to the sum of the yields of C₄H₆ isomers in any experiment. ?_CO was 0.43 at the total pressure of 6.5 torr and 0.20 at 500 torr. We did not succeed in detecting any addition products such as C₅H₆O isomers. It was found that 3-methylcyclopropene was produced with excess energy and was partly isomerized to other C₄H₆ isomers, especially to 1-butyne. The excess energy was estimated to be about 50 kcal/mol. The rate coefficient of the reaction was obtained relative to those for the reactions of atomic oxygen with trans-2-butene and 1-butene. The ratios k_CPD+O/k_{trans-2-butene+O}= 2.34 and k_CPD+O/k_1-butene+O = 11.3 were obtained. Probable reaction mechanisms and intermediates are suggested.     

The interaction of ruthenium with a MgO matrix

Ruthenium samples supported on MgO have been prepared and investigated by Thermal Programmed Reduction. Several TPR peaks have been observed and their assignment to chemical species containing reducible ions has been discussed.     

A practical valence bond method: a configuration interaction method approach with perturbation theoretic facility

The previously developed valence bond configuration interaction (VBCI) method (Wu, W.; Song, L.; Cao, Z.; Zhang, Q.; Shaik, S., J. Phys. Chem. A, 2002, 105, 2721) that borrows the general CI philosophy of the MO theory, is further extended in this article, and its methodological features are improved, resulting in three accurate and cost-effective procedures: (a) the effect of quadruplet excitation is incorporated using the Davidson correction, such that the new procedure reduces size consistency problems, with due improvement in the quality of the computational results. (b) A cost-effective procedure, named VBCI(D, S), is introduced. It includes doubly excited structures for active electrons and singly excited structures for inactive pairs. The computational results of VBCI(D, S) match those of VBCISD with much less computational effort than VBCISD. (c) Finally, a second-order perturbation theory is utilized as a means of configuration selection, and lead to considerable reduction of the computational cost, with little or no loss in accuracy. Applications of the new procedures to bond energies and barriers of chemical reactions are presented and discussed.     

Roughening of gold atomic steps induced by interaction with tetrahydrofuran

Exposure of a clean gold surface to tetrahydrofuran (THF) under ambient conditions was observed to cause roughening of atomic step edges. This change was followed in situ using a scanning tunneling microscope during the exposure of a gold surface to a controlled stream of THF vapor. THF is a common solvent used in depositing molecules, self-assembled monolayers, and polymer films on surfaces, in electrochemistry, and in chemical reactions. Unlike other solvents, such as methanol, ethanol and diethyl ether, however, we found that THF itself has a profound effect on the surface morphology that needs to be taken into account when reporting on the interactions of solutes with a gold surface. At the same time, this finding may present new opportunities in catalysis or nanostructuring of surfaces.     

Determination of sub-nanogram quantities of ruthenium by flameless atomic absorption spectrometry

Flameless atomic absorption spectrometry has been applied to the determination of subnanogram quantities of ruthenium in a variety of matrices encountered in the solidification of nuclear waste. Detection limits ranged to below 10^?10 g, depending on the sample matrix. Most matrix effects could be eliminated by proper selection of atomizer temperature program, allowing the use of a single set of standards in 0.1 N HCl. The one exception was the calcined solid matrix, where a fusion and extraction were used to dissolve the ruthenium and separate it from matrix constituents.