Cathode generation of thiolate anions and the correlation between their oxidationE 1/2 and nucleophilic reactivity

Cathode reduction of a series of aliphatic, aromatic, and heteroaromatic thiols on a rotating disk Pt electrode in abs. MeCN against the background of 0.1N Bu₄NClO₄ was investigated. It was found that this process results in the formation of the corresponding thiolate anions whose oxidation half-wave potentials are linearly correlated with their nucleophilicity in theS _N 2 reaction.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2539–2544, November, 1992.     

Structural Analysis and Properties of Organic-Inorganic Hybrid Ionic Conductor Prepared by Sol-Gel Process

Organic-inorganic hybrid lithium ion conductors were prepared by the sol-gel process. The hybrid ion conductor will be used as the electrolyte for Li based high-energy density batteries. The hybrid ion conductor was prepared from a mixture of tetramethyl orthosilicate (TMOS), polyethylene glycol 200 (PEG₂₀₀), lithium perchlorate (LiClO₄) and water. A wet gel was prepared at room temperature. The gels dried at 80°C under vacuum did not contain water. The dried hybrid ion conductor gel had homogeneity and high transparency. Ionic conductivity of the hybrid sample was measured by the complex impedance method and it increased with increasing PEG₂₀₀ content. The dried hybrid gel that contained no LiClO₄ did not show ion conduction. Conductivity on the order of 10^–5 S·cm^–1 at room temperature was obtained. Structural characterization was done by Fourier Transform Infrared Spectra (FTIR) and NMR measurement of ¹³C and ¹H, and the thermal stability and glass transition properties were studied by DSC. Glass transition temperature decreased with increasing PEG₂₀₀ content and increased with increasing [Li]/[O] ratio (the oxygen considered is from the polyethylene glycol). Existence of the Si–O–(C₂H₄O) _n –bond and the C–OH bond in the framework of the organic and inorganic phases was confirmed. TMOS and PEG₂₀₀ were hydrolyzed and condensed. The organic and inorganic phases were chemically bonded and the microstructure of the hybrid matrix was shaped as comb. The comb shape leads to high ionic conduction.     

Coordination compounds of disulphur dinitride

Summary Coordination compounds of the S₂N₂ molecule including methods for their preparation, reactivities, i.r. data, structures, and aspects of chemical bonding are reviewed. Methods of synthesis include reactions of S₂N₂, S₄N₄ or (NSCl)₃ with metal halides, metal complexes such as carbonyls, or even metals themselves. In all cases, the planar S₂N₂ ring is coordinated, usuallyvia both, of its nitrogen atoms so that S₂N₂ acts as a bridging ligand between two metal centres; short contact distances imply that halogen atoms linked to the metal atoms show some interaction with the sulphur atoms. The stability of S₂N₂ is greatly enhanced by coordination. In the i.r. spectra, two characteristic S₂N₂ vibrations assist identification of the S₂N₂ species, a ring stretching mode being observable atca. 850 cm^–1 and the out-of-plane deformation at 450–490 cm^–1.     

Syntheses, structures, spectroscopic, electrochemical properties and DFT calculation of Ru(II)–thioarylazoimidazole complexes

The reaction of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles (SRaaiNR) (2a/2b) with Ru(II) has synthesized [Ru(SRaaiNR)₂](ClO₄)₂ (3a/3b) in 2-methoxyethanol. The reaction in methanol, however, has synthesized [Ru(SRaaiNR)(SRaaiNR)Cl](ClO₄) (4a/4b). The solid phase reaction of SRaaiNR and RuCl₃ on silica gel surface upon microwave irradiation has synthesized [Ru(SRaaiNR)(SaaiNR)](PF₆) (5a/5b) [SRaaiNR represents tridentate N,N′,S-chelator; SRaaiNR is N,N′-bidentate chelator where S does not coordinate and SaaiNR refers N,N′,S-chelator where S refers to thiolato binding]. The structural characterization of [Ru(SEtaaiNEt)(SEtaaiNEt)Cl](ClO₄) (4b) and [Ru(SEtaaiNEt)(SaaiNEt)](PF₆) (5b) has been confirmed by single crystal X-ray diffraction study. The IR, UV–Vis, and ¹H NMR spectral data also support the stereochemistry of the complexes. The complexes show metal oxidation, Ru(III)/Ru(II), and ligand reductions (azo/azo⁻, azo⁻/azo). The molecular orbital diagram has been drawn by density functional theory (DFT) calculation. Normal mode of analysis has been performed to correlate calculated and experimental frequencies of representative complexes. The electronic movement and assignment of electronic spectra have been carried out by TDDFT calculation both in gas and acetonitrile phase.     

Novel composite polymer electrolytes based on poly(ether-urethane) network polymer and modified montmorillonite

Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) network polymer, which is superior to poly(ethylene oxide) in mechanical stability due to its cross-linked structure, modified montmorillonite (MMMT) and LiClO₄, and CGPE with good mechanical strength comprises of the CSPE and LiClO₄–PC (propylene carbonate) solution. The ionic conductivity can be enhanced after the addition of MMMT, and CGPE exhibits ionic conductivity in the order of 10⁻³ S/cm at room temperature. The temperature dependence of the ionic conductivity of the CSPE follows the Vogel–Tamman–Fulcher (VTF) equation. The effects of MMMT on the interactions in these systems and the possible conduction mechanisms are also discussed.     

Synthesis of Polymer Films by an Electron Emission CVD Technique

A low-pressure chemical vapor deposition (CVD) technique based on the formation of reactive film precursors by dissociation of gas-phase reactants by electron impact is described. The electrons are emitted by a hot filament and a positive bias voltage applied to the substrate provides control of the emission current. The emitted electrons are primarily responsible for the gas dissociation, but secondary electrons resulting from electron-impact ionization of the gas molecules also produce reactive species, contributing to the deposition process. This technique was used to synthesize polymer films from C₂H₂–N₂ mixtures at pressures ranging from 1–10 Pa. The dependencies of the current collected by the substrate, I_S, on the substrate bias voltage, V_S, and on the gas pressure were determined. The film deposition rate was measured as a function of several deposition variables such as I_S, V_S, and the N₂ to C₂H₂ flow rate ratio. Oxygen was present in the films as a contaminant. Analyses by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy (XPS) provided insight into the film molecular structure, allowing identification of various functional groups and binding states of the C- and N–atoms. From the XPS spectra, the N/C and O/C ratios were determined.     

Synthesis and x-ray crystal structure of tetraethylammonium bis[1, 1-dicyanoethylene-2, 2-dithiolato]platinate(II)

Summary [(NEt₄)]₂[Pt(S₂C₄N₂)₂] has been prepared from K₂PtCl₄ and K₂S₂C₄N₂·H₂O with NEt₄Cl and characterized by single crystal x-ray structural analysis.The title compound crystallizes in the monoclinic space group P2₁/a witha=14.800(2),b=11.679(2),c=9.497(1) Å, =94.51(4)° andZ=2. In the complex anion Pt sits on a centre of symmetry and is coordinated by four S atoms of the ligand (S₂C₄N₂)^2– (i-mnt). The Pt–S distances are 2.315(3) and 2.316(3) Å. The intra-and interligand S–S distances are 2.807(4) and 3.682(4) Å, respectively, indicating the rectangular planar arrangement of the sulfurs about platinum. Within the isomaleonitriledithiolate there is still some suggestion of resonance indicated by the geometry of i-mnt.     

Enantioselective cathodic reduction of some prochiral ketones in the presence of (−)-N,N′-dimethylquininium tetrafluoroborate at mercury cathode

This work describes preparative scale enantioselective cathodic reduction of some prochiral ketones, viz. 3,4-dihydro-1(2H)-naphthaleneone, 2-octanone, 1-phenyl-2-propanone, E-3-octen-2-one, 1-octyn-3-one, 1-undecyn-3-one, 1-tetradecyn-3-one at mercury pool in N,N-dimethyl formamide (DMF)–2-propanol (9.5:0.5), using tetrabutylammonium tetrafluoroborate (TBA·BF₄), as supporting electrolyte and (−)-N,N′-dimethylquininium tetrafluoroborate (DMQ·2BF₄), as a enantioselective inductor. The products obtained were corresponding (S)-alcohols in 24–70% ee.     

Mechanisms for the Ni-mediated oxidation of benzene to phenol by N2O

The gas-phase Ni⁺-mediated benzene oxidation by N₂O on both quartet and doublet potential energy surfaces are surveyed using density functional theory (DFT). Geometries and energies for all relevant intermediates are calculated. The initial N₂O reduction for forming NiO⁺ takes place only via reaction with the excited Ni⁺(⁴F) through the N–O insertion mechanism. The second step of the oxidation can involve two mechanisms: ‘nonradical’ through benzene H migration following the formation of the boat complex of benzene–NiO⁺ or ‘oxygen-insertion’ via rearrangement to an arenium intermediate from the chair-type benzene–NiO⁺ encounter complex. Both mechanisms are energetically available.     

Image Intensification in Silver Halide Photographic Materials for Detection of High-Energy Radiation by Reprecipitation of Elemental Silver

A process for the intensification of silver images on AgHal photographic materials designed for detection of high-energy (X- and γ-ray) radiation was proposed, which is based on the “reprecipitation” of elemental silver and a decrease in its dispersion and comprises the treatment of silver with an aqueous solution containing potassium hexacyanoferrate(III) and potassium chloride or bromide at the first step and with a solution containing tin(II) chloride, potassium thiocyanate, sodium N,N′-ethylenediamine tetraacetate, and potassium hydroxide at the second step. By this process, the optical densities of image over a wide (0.5–2.0) range was increased by a factor of 3–5; as a result, the photographic sensitivity S _0.85 and S _2.00 was enhanced by almost an order of magnitude with the retained or slightly increased gradient g, fog density D ₀, and resolving power of the material.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 5, 2005, pp. 373–378.Original Russian Text Copyright © 2005 by Mikhailov, Kondakov, Krikunenko.     

Synthesis of some new N,N′-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines

The synthesis of a new series of six-membered N,N′-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines （5a-e） was achieved in excellent yields by Mannich-type condensation of N,N′-diarylsubstituted methylene-bis-o-hydroxybenzyl amines （4a- e） with formaldehyde in chloroform at reflux. These amines （4a-e） were obtained by the reduction of N, Nr-diarylsubstituted methylene-bis-o-hydroxybenzyl imines （3a-e） with NaBH4, which inturn were obtained by the condensation of methylene-bissalicylaldehyde （2） with various substituted arylamines.     

Electron diffraction,x-ray diffraction,and CNDO/2 analysis of the conformations,molecular geometry,and internal rotation potentials of aryldichloro- and aryldibromoarsines

A structural study was carried out on o-ClC₆H₄AsCl₂ (I), o-BrC₆H₄AsBr₂ (II), C₆H₅AsBr₂ (III), and p-BrC₆H₄AsBr₂ (IV). The normal mode frequencies and shapes were calculated and gas-phase electron diffraction was used to establish the geometric parameters of III and IV. The structure of IV was determined by x-ray diffraction structural analysis. The experimental results for I–IV (I and II were studied in previous work) were interpreted on the basis of CNDO/2 calculations for I–III.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 5, pp. 61–69, September–October, 1989.     

Nucleophilic substitution of halogen in 4-halo genated derivatives of glutamic acid

The reaction of nucleophilic substitution of bromine byp-anisidine in dimethyl (2S,4S)-and (2S,4R)-N-phthaloyl-4-bromoglutamates proceeds according to the S_N2 mechanism. The relative reactivity of diastereomers in various solvents was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 652–655, April, 1995.The authors thank M. L. Gal'perin for assistance in designing the computer program for the calculations of the kinetic parameters.     

Synthese und Röntgenstrukturanalyse des 8π-Elektronenringsystems S4N4O2Sn2(CH3)6 und des magnetische Verhalten von S4N4O2 und S8N8O4

Synthesis and X-Ray Structure Analysis of the 8π-Electron-Ring-System S₄N₄O₂Sn₂(CH₃)₆ and the Magnetic Properties of S₄N₄O₂ and S₈N₈O₄ S₄N₄O₂ reacts with N[Sn(CH₃)₃]₃ in a molar ratio of 1:1 to an eight-membered trimethyltin-substituted 8π-electron skeleton, S₄N₄O₂Sn₂(CH₃)₆. In contrast to known 6π-electronsystems this compound has tin atoms which are tetracoordinated. This was demonstrated on the basis of an x-ray analysis. S₄N₄O₂Sn₂(CH₃)₆ · 1/2 C₆H₆ crystallizes in the space group P2₁/c with a = 1396.0(4), b = 1190.3(4), c = 1256.7(3) pm, and β = 103.46(2)°. It was shown that the ability of coordination at the tin atom depends on the electron density. The magnetic properties of S₄N₄O₂ and S₈N₈O₄ were investigated by the Faraday method. The high diamagnetism in these ring compounds is caused by the π-electrons.     

Two-path reduction of molecular nitrogen by transition metal hydroxides

The kinetics of the reduction of N₂ to N₂H₄ and NH₃ by Ti^III-Mo^III hydroxide was studied at pH I I and 303-333 K, and the activation energies for these reactions and also for the reaction N₂H₄ 2 NH₃ were determined (29, 70, and 25 kJ mol^– respectively). It was concluded that -90 % of ammonia was formed by the direct reduction of N₂ without intermediate formation of hydrazine. A mechanism of this reaction is suggested, which includes the proton insertion into the N-N bond favored by an enhanced electron density at the nitrogen atoms, according to the data of the quantum-mechanical calculation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1402–1405, June, 1996.     

Sulfito- und Thiosulfato-Komplexe des Kobalts(III) mitα-Benzildioxim Überα-Dioximinkomplexe der Übergangsmetalle, 52. Mitt.

Some new ligand exchange reactions of [Co(diph·H)₂Cl(H₂O)] and [Co(diph·H)₂(SO₃)(H₂O)]^– complexes with N₃ ^–, S₂O₃ ^2– and with aromatic and heterocyclic amines were carried out. A series of derivatives of the types [Co(diph·H)₂(SO₃)X] ^n– (X=N₃ ^–, S₂O₃ ^2– oramine) and [Co(diph·H)₂(S₂O₃)₂]^3– were described and characterized. Some structural problems are resolved and discussed on the basis of UV and IR spectral data.     

Synthesis of liquid crystal ferrocene derivatives and their complexes with Cu2+

A series of liquid crystal ferrocene-containing Schiff bases of general formula C₅H₅FeC₅H₄-C₆H₄-N=CN-(X)C₆H₃-O(O)-C₆H₄-OC_nH_2n+1 (X=H, OH, n=3–12) was obtained, together with several analogs, 1,1-bis-substituted at the ferrocene fragment, having a thermotropic nematic mesophases. Derivatives with X=OH were used to obtain Cu²⁺ chelate complexes, of which the compounds with n=10 and n=12 displayed nematic liquid crystalline properties.Physicotechnical Institute, Kazan Scientific Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 402–407, February, 1992.     

Mischkristallbildung in den Systemen Co1−x Ni x Cr2S4, Cu1−x Ni x Cr2S4 und Co1−x Cu x Cr2S4 Chromchalkogenide, 5. Mitt.

Zusammenfassung Durch Zusammensintern der Elemente bzw, der binären Sulfide wurde die gegenseitige Mischbarkeit in den Systemen CoCr₂S₄–NiCr₂S₄, CuCr₂S₄–NiCr₂S₄ und CoCr₂S₄–CuCr₂S₄ untersucht. In den Thiospinellen CoCr₂S₄ und CuCr₂S₄ können bis zu 20 (26) At% des Kobalts (Kupfers) durch Nickel substituiert werden (950°C), in das monokline NiCr₂S₄ wird nur wenig Kobalt bzw. Kupfer eingebaut. Zwischen dem halbleitenden, ferrimagnetischen Kobaltchromthiospinell und der metallisch leitenden, ferromagnetischen Kupferverbindung wurde lückenlose Mischkristallbildung beobachtet. Der von derVegardschen Regel abweichende Verlauf der Gitterkonstanten wird im Vergleich mit dem elektrischen und magnetischen Verhalten der Mischkristallreihe diskutiert.

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Chromium chalcogenides, V. Miscibility within the SystemsCoCr ₂S₄–NiCr₂S₄, CuCr₂S₄–NiCr₂S₄ andCoCr ₂S₄–CuCr₂S₄

The miscibility within the systems CoCr₂S₄–NiCr₂S₄, CuCr₂S₄–NiCr₂S₄ and CoCr₂S₄–CuCr₂S₄ was studied by annealing the elements or binary sulphides. In the thiospinels CoCr₂S₄ and CuCr₂S₄, 20 per cent of cobalt and 26 per cent of copper, resp., can be substituted by nickel at 950°C. In monoclinic NiCr₂S₄, only small amounts of cobalt or copper are dissolved. The formation of a complete solid solution series was observed between the semiconducting ferrimagnetic CoCr₂S₄ and the metallic conducting ferromagnetic CuCr₂S₄. The deviation fromVegard's rule of lattice constants is discussed with respect to the electrical and magnetic behaviour of the solid solution series.

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Mit 3 Abbildungen     

Borohydride reduction of acetophenone and esters of dehydrocarboxylic acids in the presence of chiral cobalt(<Emphasis Type="SmallCaps">II</Emphasis>) diamine complexes

The catalytic reduction of acetophenone, methyl α-acetamidocinnamate, and dimethyl itaconate with alcohol-modified sodium borohydride was studied in the presence of complexes CoCl₂·L₂ (L₂ are chiral C ₂-symmetric diamines: (4S,5S)-2,2-dimethyl-4,5-bis(aminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(methylaminomethyl)-1,3-dioxolane, (4S, 5S)-2,2-dimethyl-4,5-bis(dimethylaminomethyl)-1,3-dioxolane, and (4S, 5S)-2,2-dimethyl-4,5-bis(diphenylaminomethyl)-1,3-dioxolane). The maximum enantiomeric excess of (S)-1-phenylethanol was 24%, that of dimethyl α-methylsuccinate was 38%.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 342–347, February, 2005.