Crystal structure of the synthetic analog of radtkeite Hg<Subscript>3</Subscript>S<Subscript>2</Subscript>Cl<Subscript>1.00</Subscript>I<Subscript>1.00</Subscript>

The results of structural studies of the synthetic analog of the radtkeite mineral Hg₃S₂Cl_1.00I_1.00 are analyzed. The crystal structure of the compound has been refined; the unit cell parameters are a _m = 16.827(4) , b _m = 9.117(1) , c _m = 13.165(5) , = 130.17(2)°, V = 1543.3(8) ³, space group C2/m, Z = 8, R = 0.0527. A possible transition a ₀ = a _m; b ₀ = a _m + 2c _m; c ₀ = –b _m to the pseudo-orthorhombic F cell previously determined for radtkeite, where one of the angles ( ₀ ) is slightly different from 90° (89.55°), has been found. Each sulfur atom in the structure is bonded to three mercury atoms, forming SHg₃ umbrellas with distances 2.240(6) –2.474(8) and angles HgSHg 94.7(2)°–102.9(2)°. The SHg₃ fragments are linked through Hg vertices to form corrugated [Hg₁₂S₈] layers. The halogen atoms lie inside and between the [Hg₁₂S₈] layers; the distances are Hg-Cl and Hg-I 2.783(7) , 2.961(7) , and 3.083(4) –3.311(3) , respectively.Original Russian Text Copyright © 2004 by N. V. Pervukhina, S. V. Borisov, S. A. Magarill, D. Yu. Naumov, V. I. Vasiliev, and B. G. NenashevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 755–758, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Phase equilibria in the CdI<Subscript>2</Subscript>-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The phase diagram of the system CdI₂-Bi₂O₃ is studied by means of X-ray diffraction, differential thermal analysis and measurements of the density of the material. As a result of the synthetic and peritectic interactions, two incongruently melting intermediate phases i.e. phase A — CdI₂·2Bi₂O₃ and phase B — CdI₂·4Bi₂O₃ (stable in the temperature interval 370–850°C) are formed.The phase A exists in two polymorphic forms with a temperature of the phase transition T =320–370°C. The unit cell parameters at low temperature modification of -CdI₂°2Bi₂O₃ were determined. (a=1.032 nm, b=1.046 nm, c=1.046 nm, =115.02°, =109.11° and =82.04°). The phases A and B have fields of homogeneity.The authors acknowledge thankfully the financial support for this work from the Ministry of Education and Science (Fond Scientific investigations — contract TN-1102).     

Electrochemical oxidation and reduction of La<Subscript>4</Subscript>Ni<Subscript>3</Subscript>O<Subscript>10</Subscript> in alkaline media

In this work we used electrochemical polarization for oxidizing and reducing, in a controlled way, the Ruddlesden-Popper phase La₄Ni₃O₁₀. With a careful choice of electrochemical parameters, we were able to obtain samples of La₄Ni₃O_10± never obtained before. The oxygen stoichiometry can range between 9.78 (=–0.22) and 10.12 (=0.12). The oxidized phase, La₄Ni₃O_10.12, was obtained using a galvanostatic mode (I=20 A) and the reduced phase, La₄Ni₃O_9.78, using potentiostatic conditions (E=0.46 V). The evolution of the electrical conductivity has been studied as a function of .     

X-ray spectral investigation by synchrotron radiation of supported Re/SiO2 and (Re+Pt)/SiO2 catalysts prepared via triethoxyrhenium

Using synchrotron radiation L_III absorption spectra of rhenium in Re/SiO₂ and (Re+Pt)/SiO₂ catalysts prepared via triethoxyrhenium have been studied. The conclusion has been drawn that reduced catalysts contain lowvalent rhenium ions and their composition is more uniform than that of the previously examined catalysts Re/Al₂O₃ and (Re+Pt)/Al₂O₃ prepared by a conventional impregnation technique.

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L_III- Re/SiO₂ (Re+Pt)/SiO₂, . , , Re/Al₂O₃ (Re+Pt)/Al₂O₃, .

     

State of components in Pd/C catalysts promoted by Ho2O3

Catalysts prepared through the interaction of C₃H₅PdC₅H₅ with the surface of evacuated Ho₂O₃/C after reduction by H₂ at 573 K contain Pd and Ho₂O₃ particles whose size is 30 and 20–40 Å, respectively. XPS and TEM data indicate that Pd particles have a positive charge and their surface is partly covered by Ho oxide.

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, C₃H₅PdC₅H₅ Ho₂O₃/C, H₂ 573 Pd 30 Å Ho₂O₃ 20–40 Å. XPS TEM Pd , Ho.

     

Characteristics of CuAl<Subscript>2</Subscript>-Cu<Subscript>9</Subscript>Al<Subscript>4</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanocomposites synthesized by mechanical treatment

Summary Reactive milling of Cu-hydroxycarbonate - powder aluminium mixture brings many complex chemical reactions such as decomposition, aluminothermic reduction and mechanical alloying resulting in the formation of nanometer size composites that contain intermetallic phases, -Cu₉Al₄ and -CuAl₂, with aluminium oxide.     

Thermal decomposition of thorium(IV) benzenetricarboxylates prepared in various ways

The thermal decompositions of thorium(IV) trimesinate and trimellitate, prepared under various conditions, have been studied. On heating benzenetricarboxylates of Th(IV) decompose in many stages. First, the hydrated complexes lose crystallization water in one, two or four stages, forming anhydrous comtlexes which decompose to ThO₂ with the intermediate formation of ThOCO₃. The dehydrations of the complexes are associated with strong endothermic effects, and the decompositions of the anhydrous complexes are accompanied by exothermic effects.

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Zusammenfassung Thorium-(IV)-trimesinat und -trimellinat wurden unter verschiedenen Bedingungen gefertigt und ihre thermische Zersetzung untersucht. Beim Erhitzen zersetzen sich Benzyltricarboxylate von Th(IV) in mehreren Stufen. Als erstes geben die hydrierten Komplexe in ein, zwei oder vier Schritten Kristallwasser ab. Die dehydrierten Komplexe zersetzen sich über das Zwischenprodukt ThOCO₃ zu ThO₂. Die Dehydrierung der Komplexe ist mit starken endothermischen Effekten verbunden, während die Zersetzung der dehydrierten Komplexe von exothermen Effekten begleitet wird.

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, . . , , , ThOCO₃. , — .

     

IR spectra of CO and NO adsorbed on CuO

The original heterogeneity of CuO surface is suggested to account for the presence of two states of surface copper cations with different effective charges.

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CuO, . , .

     

Infrared and mass spectroscopic evidence for hydrocarbon formation on a supported cobalt catalyst

Interrupting the surface carbonyl development at 345 K on an aerosilsupported cobalt oxide catalyst in CO/H₂ atmosphere at maximum surface concentration of linear carbonyl species by heating to 475 K results in the formation of Fischer-Tropsch type products detectable by combined IR and MS measurements.

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345°K , , CO/H₂ , 475° -, .

     

<Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR spectra of some drimanic sesquiterpenoids

One- and two-dimensional homo- and heteronuclear correlation proton, carbon, proton—proton, and proton—carbon NMR spectra of fifteen drimanic sesquiterpenoids: 11,12-dibromodrima-5,8-dien-7-one, drim-8-en-7-one, 11-hydroxydrim-8-en-7-one, 11,12-dihydroxydrim-8-en-7-one, 11-hydroxy-11,12-epoxydrim-8-en-7-one, 11-hydroxy-11,12-epoxydrim-8-en-7-one, 8,9-epoxydriman-7-one, 8,9-epoxydriman-7-ol, 11,12-diacetoxydrim-8-en-7-ol, drimane-7,8,11-triol, 7,8-isopropylidenedioxydriman-11-al, 9, 11-dihydroxydrim-7-en-6-one, drimane-7,8,9-triol, drimane-7,8,11-triol, and drim-8-ene-7,11,12-triol were studied. The proton and carbon chemical shifts were assigned.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2589–2594, December, 2004.     

Formation of a Hydroxo-bridged Dinuclear Ru(III)/Ru(III) Complex from <Emphasis Type="Italic">N</Emphasis>-Methylimidazole and [Ru<Emphasis Type="Italic">Cp</Emphasis>(CH<Subscript>3</Subscript>CN)<Subscript>3</Subscript>]<Superscript>+</Superscript>

Summary. The reaction of [RuCp(CH₃CN)₃]PF₆ with 1 equiv of N-Me-imidazole results in the quantitative formation of [RuCp(¹N-N-Me-imidazole)(CH₃CN)₂]PF₆ (1) featuring a ¹N rather than a ¹C bound N-Me-imidazole ligand. According to DFT/B3LYP calculations, ¹N coordination of N-Me-imidazole is preferred over ¹C coordination by 25.5kJ/mol. Upon exposure to air 1 reacts with oxygen and water to afford the novel hydroxo-bridged dinuclear complex of [Ru₂Cp₂(¹N-N-Me-imidazole)₂(-OH)₂](PF₆)₂ (2) featuring a metal-metal single bond. The dimeric nature of 2 was confirmed by a single-crystal X-ray structure analysis.     

ESR study of the interaction of tribenzyltitanium with diisobutylaluminium chloride

ESR studies of the interaction between⁴⁷Ti enriched tribenzyltitanium and diisobutylaluminium chloride suggest that the observed spectral peculiarities show the formation of the alkylhalide complex of Ti ₂ ⁷⁺ .

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⁴⁷Ti, . Ti ₂ ⁷⁺ .

     

Synthesis,Structure, and Magnetic Properties of the Silicides <Emphasis Type="BoldItalic">RE</Emphasis>IrSi (<Emphasis Type="Italic">RE</Emphasis> = Ce,Pr, Er,Tm, Lu) and SmIr<Subscript>0.266(8)</Subscript>Si<Subscript>1.734(8)</Subscript>

Summary. The equiatomic rare earth metal–iridium–silicides REIrSi (RE=Ce, Pr, Er, Tm, Lu) were prepared by arc-melting of the elements and subsequent annealing. All silicides were characterized through their X-ray powder patterns. The structures of CeIrSi, ErIrSi, and LuIrSi were refined from X-ray single crystal diffractometer data: LaIrSi type, P2₁3, a=629.15(2)pm, wR2=0.1232, 280F² values, and 11 variable parameters for CeIrSi; TiNiSi type, Pnma, a=673.4(1), b=416.07(5), c=744.88(9)pm, wR2=0.0705, 339F² values, and 20 variable parameters for ErIrSi, and a=664.0(3), b=412.9(1), c=742.6(1)pm, wR2=0.0398, 496F² values, and 20 variable parameters for LuIrSi. The iridium and silicon atoms in CeIrSi, ErIrSi, and LuIrSi build three-dimensional [IrSi] networks where the iridium atoms have three (CeIrSi, Ir–Si 229pm) and four (ErIrSi, Ir–Si 247–258pm; LuIrSi, Ir–Si 245–256pm) silicon neighbors. The [IrSi] networks leave larger channels in which the cerium, erbium, and lutetium atoms are located. Temperature dependent susceptibility data for LuIrSi indicate Pauli paramagnetism. CeIrSi shows Curie-Weiss paramagnetism above 100K with an experimental magnetic moment of 2.56(2)_B/Ce atom. With samarium as rare earth metal component the silicide SmIr_0.266(8)Si_1.734(8) with -ThSi₂ type structure was obtained: I4₁/amd, a=409.3(1), c=1397.2(5)pm, wR2=0.0575, 161F² values, and 9 variable parameters. Within the three-dimensional [Ir_0.266Si_1.734] network the Ir/Si–Ir/Si distances range from 230 to 237pm.     

An inverse DIE method

The inverse of the usual DIE method is presented. The solid or liquid samples are introduced successively into the reagent of high concentration and large volume, and the change in temperature is measured after each sample. In principle the measuring unit need not be opened until the reagent is exhausted. The new technique is rapid and economical.

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Zusammenfassung Ein Inversverfahren der üblichen DIE-Methode wird beschrieben. Die festen oder flüssigen Proben werden der Reihe nach in das hochkonzentrierte Reagenz von großem Volumen eingeführt und die Temperaturänderungen nach jeder Probe gemessen. Im Prinzip muß die Messeinheit bis zur Erschöpfung des Reagenzes nicht geöffnet werden. Das neue Verfahren ist schnell und wirtschaftlich.

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Résumé La publication présente une méthode inverse de celle de DIE utilisée de coutume. On introduit les prélèvements solides ou liquides un à un dans le réactif de forte concentration et de grand volume et on effectue la mesure des variations de température après chaque prélèvement. En principe, il n'est pas nécessaire d'ouvrir l'unité de mesure avant que le réactif ne soit épuisé. La nouvelle technique est rapide et économique.

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, . , . , . .

     

Density Functional Theory and Low-Temperature Matrix Investigations of CO-Loss Photochemistry from [(C<Subscript>5</Subscript>R<Subscript>5</Subscript>)Ru(CO)<Subscript>2</Subscript>]<Subscript>2</Subscript> (R = H,Me) Complexes

The photochemical CO-loss products of the diruthenium complexes [CpRu(CO) ₂]₂ (5; Cp = ⁵-C₅H₅), [Cp*Ru(CO)₂]₂ (5*; Cp* = ⁵-C₅(CH₃)₅) and CpCp*[Ru(CO)₂]₂ (5) have been studied experimentally in low-temperature (96 K) matrices in 3-methylpentane by using IR spectroscopy. It is proposed that all three complexes undergo single-CO-loss chemistry but that the products have different structures. The single-CO-loss product from 5 is proposed to have one bridging and two terminal carbonyl ligands, whereas 5* and 5 generate triply bridged CO-loss products similar to that observed from [CpFe(CO)₂]₂ and [Cp*Fe(CO)₂]₂. Double-CO-loss from 5* and 5* 9 is also apparently observed. Relativistic DFT calculations have been carried out on various isomers of the starting materials and on potential CO-loss products from 5. The calculations suggest that the triply bridged product Cp₂Ru₂(-CO)₃ (6) might have a singlet ground state in contrast to the corresponding diiron complex Cp₂Fe₂(-CO)₃ (3), which has a triplet ground state.     

Ruthenium(VI) catalyzed oxidation of sodium salts of lactic, tartaric and glycolic acid by alkaline hexacyanoferrate(III)

The kinetics of ruthenium(VI) catalyzed oxidation of sodium salts of lactic, tartaric and glycolic acid by hexacyanoferrate(III) in aqueous alkaline medium have been studied at constant ionic strength. The reaction shows first order dependence on ruthenium(VI) and zero order on hexacyanoferrate(III). The rate of reaction increases with increasing substrate concentration and shows Michaelis-Menten type behavior. The rate of reaction decreases with increase in hydroxide ion concentration. Oxidation proceeds via formation of a complex between substrate and ruthenium(VI). A probable mechanism is suggested.

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(VI) , (III) . (VI) (III). -. . (VI). .

     

Influence of chemical nature and concentration of the catalyst on hydrocarbon pyrolysis

The dependence of pyrolysis rate of hydrocarbons on the concentrations of catalysts of various chemical nature has been studied. Substances active in pyrolysis can be divided into three groups: inhibiting the reaction and enhancing either its homogeneous or heterogeneous components.

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. , : , .

     

Crystal structure of Ba(VUO<Subscript>6</Subscript>)<Subscript>2</Subscript>

The crystal structure of Ba(VUO₆)₂ was determined by X-ray diffraction at 243 K: monoclinic crystal system, space group P2₁/c, unit cell parameters a=6.4992(6) Å, b=8.3803(8) Å, c=10.4235(9) Å, =104.749(2) °, Z=2. The structure contains close-packed [VUO₆] ₂ ^- layers formed by the dimers of the flattened U₂O₁₂ pentagonal bipyramids and by the dimers of V₂O₈ square pyramids. The neighboring layers are bound by the statistically distributed barium atoms.Original Russian Text Copyright © 2004 by E. V. Alekseev, E. V. Suleimanov, E. V. Chuprunov, and G. K. FukinTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 544–548, May–June 2004.