A simplified View of δ → δ* Transition Energies in Compounds with multiple metal-metal bonds: The isolated δ — δ* manifold model

The energetics of the * transition in quadruply bonded complexes are investigated using a very simple valence-bond formalism, called the isolated * manifold (IDDM) model. In this model all electrons except for those that occupy the or * molecular orbitals are ignored, as are explicit metal-ligand interactions. The resulting equations allow the calculation of transition energies very inexpensively, albeit with poor quantitative agreement: the * transition in prototypical quadruple-bond systems is predicted to occur at energies greater than 70,000 cm¹. The model incorporates configuration interaction between the two¹ A _1g configurations (|| and |**|) to roughly the same extent as do correlated all-electron calculations. The application of the method to systems that involve relative changes in * transition energies, such as the torsional twisting of quadruple bonds, is more successful quantitatively.     

Lattice Dynamics in LaTa2-2xNb2xVO9-δ (x=0–0.1) Solid Solutions

The oxygen nonstoichiometry (x) of LaTa_2-2xNb_2xVO₉- (x = 0–0.1) solid solutions was studied using Xray phase analysis, vibrational spectroscopy, and radiospectroscopy. A correlation was found between (x) and the unit cell volume V(x) of the solid solutions. It was shown that the infrared spectra of LaTa₂VO₉- change in passing from = 0 to 0. The structural position of the oxygen vacancy in LaTa_2-2xNb_2xVO₉- is discussed.     

Pt(alizarine)2 complex adsorbed on titanium dioxide as a sensitizer in photocatalytic evolution of dihydrogen

Pt(alizarine)₂ complex adsorbed on the surface of titanium dioxide has been found to cause spectral sensitization of the photocatalytic activity of TiO₂. Adsorption of the complex provides simultaneously sensitization of the photoprocess and catalysis of dark steps of dihydrogen formation.

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, Pt()₂ TiO₂. , , .

     

Azole- and δ2-azolinecarbaldehyde oximes and their derivatives

The production of 1-methyl-substituted pyrazole-, imidazole-, ²-pyrazoline-, and ²-imidazolinecarbaldehyde oximes is described. The alkylation of 1-methylimidazole-and 1-methyl-²-pyrazolinecarbaldehyde oximes with methyl iodide and ,-dihalo-genoalkanes forms quaternary and bisquaternary ammonium derivatives, respectively. The quaternary derivatives of 1-methylpyrazolecarbaldehyde oximes are obtained by the oximation of the corresponding quaternary derivatives of the aldehydes; the direct methylation of these oximes either does not take place or leads to the formation of nitrones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1093–1098, August, 1973.The melting points were determined on a Kofler block.     

Synthesis of δ-alkoxy-α, α-dicarbonyl-substituted dienes and study of their valence isomerization

Methods of synthesis of dienic -alkoxy-, -dicarbonyl-substituted compounds were experimentally examined. The structure of the synthesized compounds was studied by¹H and¹³C-NMR methods. It was shown that the -alkoxy diesters are present in equilibrium with 2H-pyrans, while -alkoxy--methyl diesters and 2-(3-alkoxypropen-2-ylindene)indanediones exist in an open form and do not undergo cyclization into 2H-pyrans.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2561–2565, November, 1990.     

The specific surface area and catalytic properties of the calcination products of δ-FeOOD

The effect of calcination temperature on the structure, specific area and catalytic activity of samples obtained from -FeOOH and -FeOOD was studied. It was found that, as a result of dehydratation, the samples differ mainly in specific surface area and in their catalytic properties.

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Spezifische Oberfläche und katalytische Eigenschaften der Calcinierungsprodukte von -FeOOD

Zusammenfassung Der Effekt der Calcinierungstemperatur auf die Eigenschaften von Proben aus -FeOOH und -FeOOD wurde untersucht. Die dehydratisierten Produkte unterschieden sich—bei sehr ähnlichen Strukturen—hauptsächlich bezüglich spezifischer Oberfläche und katalytischer Aktivität.

     

Some methoxy derivatives of 9-amino-6-nitroacridine

The reaction of the 2-, 3-, and 4-methoxy derivatives of 9-chloro-6-nitroacridine with-diethylamino--methylbutylamine and with-diethylamino--hydroxypropylainine in phenol has given the 2-, 3-, and 4-methoxy derivatives of 9-(-diethylamino--methylbutylamino)-6-nitroacridine and of 9-(-diethylamino--hydroxypropylamino)6-nitroacridine, respectively.     

Carbon-13NMR spectra of isomeric diazaphenanthrenes,II δ-Effects in sterically crowded methyl derivatives

Steric downfield shifts due to a -CH moiety and a -nitrogen lone pair are similar in methylated diazaphenanthrenes. Most probably steric distortions are responsible for the -effects observed, and this might be quoted as a further evidence for a nearly equal steric requirement of a hydrogen atom and a nitrogen lone pair.

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C-13 NMR-Spektren isomerer Diazaphenanthrene, II. -Effekte in sterisch gehinderten Methylderivaten

Zusammenfassung Sterisch bedingte Tieffeldverschiebungen infolge von -CH-Molekülteilen und -lone pairs von Stickstoffatomen sind in methylierten Diazaphenanthrenen ähnlich. Die gemessenen -Effekte dürften auf sterische Deformationen zurückzuführen sein, was als weiteres Indiz für den nahezu gleichgroßen Raumbedarf eines Wasserstoffatoms und eines freien Elektronenpaars am Stickstoff gewertet werden kann.

     

Pyrroloindoles. 15. Synthesis of tryptamine analogs. 6,7-dihydro-3-(2-phthalimidoethyl)-1h,5h-pyrrolo[2,3-f]indole and 3-(2-phthalimidoethyl)-1H,5H-pyrrolo[2,3-f]indole

Diazotization of 1-acetyl-S-aminoindoline and reaction of the diazonium salt with ethyl -acetyl--phthalimidovalerate gave the 1-acetyl-5-iruiolhgl hydrazone of ethyl -keto--phthalimidovalerate. Cyclization of the hydrazone and subsequent hydrolysis, decarboxylation, and dehydrogenation of the pyrroloiruloline gave the corresponding tryptamines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 209–212, February, 1994. Original article submitted July 20, 1993.     

Reactions of arylhydrazines with α-formyl derivatives of six-and seven-membered ring lactams

Reactions of -formyl derivatives of N-methyl--valerolactam and N-methyl--caprolactam with arylhydrazines lead to the formation of 3,4,5,10-tetrahydroazepino [3, 4-b] indole-1 (2H)-one and 2,3,4,5,6,11-hexahydro-1H-azocino [3,4-b] indol-1-one derivatives. As the size of the lactam ring is increased the role of competing reactions, such as dealkylation at the indole nitrogen atom and the formation of 5-pyrazolone via reaction with -unsubstituted phenylhydrazine, also increases.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1398–1403, October, 1988.     

Ramanspektroskopie an Oxidschichten auf Reineisen im Elektrolyten

Zusammenfassung In situ durchgeführte ramanspektroskopische Messungen an Reineisen in 1 M KOH ergaben nach Oxidations-Reduktions-Cyclen (ORC) Ramanspektren der gebildeten Oberflächenfilme, die dem -FeOOH zugeordnet werden können. Durch fortgesetztes Cyclieren erfährt das -FeOOH — wie aus dem Ramanspektrum ersichtlich — eine Umwandlung in Magnetit, der an den Oxidations- und Reduktionsprozessen nicht mehr teilnimmt. Bei Benutzung hoher Potentialänderungsraten bilden sich sekundäre rostbraune Schichten blättriger Natur, deren Spektrum hauptsächlich dem des -FeOOH entspricht. Wir vertreten die Auffassung, daß das primär gebildete -FeOOH Bestandteil der Passivschicht sein könnte bzw. dieselbe repräsentiert.

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Raman spectroscopy of oxide layers on pure iron in electrochemical environment

Summary In situ Raman spectroscopy of the oxide films formed on pure iron in 1 M KOH electrolyte after special oxidation-reduction cycles (ORC) shows a Raman spectrum of -FeOOH. By subsequent cycling the -FeOOH is converted to Fe₃O₄, which further on does not take part in the oxidation and reduction processes. By higher potential sweep rates a brown rusty layer of a nearly non-adhesive material is formed, which was identified by Raman spectroscopy as mainly -FeOOH. We tentatively assign the -FeOOH-signal to the passivation layer.

     

Electrophilic heterocyclization of unsaturated carboxylic acids in the synthesis of lactones (review)

Data on the electrophilic-heterocyclization reactions of , - and , -unsaturated carboxylic acids are correlated. The use of this reaction for the synthesis of substituted mono-, bi-, tri-, and polycyclic - and -lactones is demonstrated. Data on the regioselectivity of the addition of electrophiles and the stereochemistry of the resulting cyclization products are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1316, October, 1988.     

Investigation of ethylene interaction with some oxidants in the presence of Pd2+ in acetic acid

The composition of products from the interaction of ethylene with some o oxidants, catalyzed by palladium acetate in acetic acid has been studied, An assumption is made on the possible reason for the influence of such oxidants on the selectivity of formation of ethylene glycol ethers.

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, , . .

     

Synthesis of γ- dihydropyrones and β- dihydrofuranones on the basis of acetylenic γ- and δ-keto alcohols and acetals of γ- and δ-formyl alcohols

Acetylenic - and -keto alcohols and acetals of acetylenic - and -keto alcohols and acetals of acetylenic - and -formyl alcohols undergo cyclization to -dihydropyrones and -dihydrofuranones under the influence of acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1473, November, 1976.     

X-ray studies of ZSM-5 zeolites with framework cations of various sizes

From a comparison of the X-ray difractograms for various ZSM-5 zeolites the isomorphous substitution of framework Si⁴⁺ by large cations (Al³⁺, Ga³⁺, Fe³⁺) is suggested to be ordered as contrasted to the statistical substitution by small ones (B³⁺).

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ZSM-5 , Si⁴⁺ (Al³⁺, Ga³⁺, Fe³⁺) , (B³⁺).

     

Effect of oxygen on reduction of NO with carbon monoxide over NiO and Cr2O3

Cr₂O₃ is found to be a less active catalyst than NiO in reduction of nitrogen oxides. Introduction of molecular oxygen into the NO–CO mixture decreases the conversion of NO_x on both catalysts. On NiO it is due to competition between O₂ and nitrogen oxides for CO. On Cr₂O₃ it is caused by the complete suppression of this reaction.

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Cr₂O₃ , NiO. NO CO NO_x ; NiO CO , Cr₂O₃- .

     

Über die Strukturänderung der Söderberg-Anode im Laufe der Elektrolyse

Zusammenfassung Es wurde die Änderung der Struktur der Söderberg-Anode im Laufe der Elektrolyse mit Hilfe der thermischen und mikroskopischen Analyse untersucht. Die Anode wurde in 10 Teilen von oben bis zu ihrem Unterteil im Elektrolyt aufgeteilt und die Teile separat der Untersuchung unterworfen. Die Ergebnisse gaben ausreichende Informationen über die Bildung des Sekundärkokses und über die Ausbildung der Inhomogenität in der Länge der Anode.

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Transformation of the anode structure during the electrolysis process was studied by means of thermal analysis and microscopy. The DTA method was found to be a good complement to traditional microscopic analysis. The autors succeeded in differentiating the formation and development of a secondary coke structure. The secondary coke is formed over half the anode length in the direction of the melt.

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. , . . .

     

X-ray studies of interaction between magnesium chloride and ethyl benzoate, components of the catalyst for propylene polymerization

X-ray studies of the interaction between highly dispersed magnesium dichloride and ethyl benzoate (EB) at different molar ratios EB/MgCl₂, and the effect of their grinding indicate that a new compound of MgCl₂ and EB is formed. Grinding destroys the crystal phase of the new compound, thus increasing the activity and stereospecificity of the catalyst obtained.

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() /MgCl₂, . , MgCl₂. , .

     

La and Zn promotion of Ru Fischer-Tropsch catalysts

An investigation of the use of La- and Zn-promoters for Ru/SiO₂ F-T catalysts has been carried out. It was found that, while the use of a La-promoter did not result in any improvement over the use of a K one, Zn-promotion resulted in much higher yields of olefins. The CH₄ and olefin selectivities of the Zn-promoted Ru/SiO₂ were essentially insensitive to temperature over the range 250–320 °C. The Zn-promoted catalyst was found to have many of the same catalytic properties previously found for Ru/ZnO, but was much more active. Thus, it is possible to achieve certain interesting catalytic properties for Ru by the use of Zn-promotion without having to make use of the low surface area support ZnO.

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La Zn- Ru/SiO₂ F-T. , , La- - , Zn- . CH₄ Zn- Ru/SiO₂ , -, 250–320°C. Zn- , Ru/ZnO, . Ru, Zn- ZnO .

     

Study of the interaction of atomic oxygen and nitrogen with ruthenium by the bond interaction method

The heats of atomically adsorbed oxygen and nitrogen on Ru(0001) and Ru(1010) planes have been calculated by the semiempirical bond interaction method. The calculations show that oxygen is strongly adsorbed on ruthenium, while molecular nitrogen cannot be chemisorbed on ruthenium.

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- (000I) (I0I0) . , Ru , .