Crystal and molecular structure of organic semiconductor (ET)8[Hg4Cl12] · 2C6H6

A new organic semiconductor, (ET)₈[Hg₄C1₁₂] · 2C6H6, obtained in the ET⁺-HgCl ₃ ^– -PhF system has been studied by X-ray structural analysis. Radical cations of bis(ethylenedithio)tctrathiafulvalene (ET) in the organic layer of the structure are packed in stacks ofa-type. The average angle between the planes of ET cations from adjacent stacks is 50.1°. The anionic layer is formed by four-charge centrosymmetric [Hg₄Cl₁₂]^4– complexes and benzene solvate molecules. A comparative crystal-chemical study of the salts obtained by the reaction in the ET⁺-HgX ₃ ^– -PhY system (where X = Cl, Br, and I; Y = F, Cl, and Br) made it possible to reveal a substantial effect of the sizes of the X and Y atoms on the composition of the salts and on the structural characteristics of the layers, which are responsible for the various conductivities of these salts.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 386–391, February, 1996     

Determination of copper(I)-ethylene complexes, [Cu(C2H4)]+ and [Cu(C2H4)2]+, with aid of EDTA titration of copper(I) and copper(II) ions

Summary Volumetric measurements of ethylene and simple EDTA titration of copper(I) and copper(II) ions confirm that [CuL]⁺ and [CuL₂]⁺ are formed when an aqueous solution of copper(II) is reduced by copper metal in the presence of ethylene, (L). The formation constants,K ₁=[CuL⁺]²[Cu²⁺]^–1[L]^–2 andK ₂=[CuL ₂ ⁺ ]^–1[L]^–1, have been estimated. The formation of [CuL]⁺ is accompanied by an enthalpy change, H, of –25 kJ mol^–1, and a positive entropy change, S, of 13 J mol^–1 K^–1.     

Viscosity of aqueous NH4Cl and tracer diffusion coefficients of ions,water and non-electrolytes in aqueous NH4Cl,KI, and MgCl2 at 25°C

Viscosities for aqueous NH₄Cl and tracer diffusion coefficients for²²Na⁺,³⁶Cl^–, HTO, and CH₃OH, acetone and dimethylformamide (all¹⁴C-labelled) in NH₄Cl supporting electrolyte are reported for 25°, together with tracer diffusion coefficients for²²Na⁺,³⁶Cl^–, and¹⁴CH₃OH in 1M KI, and for¹⁴CH₃OH in 1M MgCl₂. The diffusion coefficient of HTO in NH₄Cl solutions is slightly larger, for most of the concentration range investigated (0.05 to 4.5 M), than the value for pure water and is almost unaffected by the supporting electrolyte up to about 4M. Similar behavior is shown by CH₃OH, acetone and dimethylformamide in NH₄Cl solutions. Onsager limiting law behavior is approached by Cl^– at NH₄Cl concentrations in the 0.05–0.1M region but at much lower concentrations by Na⁺.     

Synthesis of hexylthiols C6H13SH−1/1, 2, 3, 4−14C1/4/' /1-thiol[35S]/ and C6H13SH−2/1, 2, 3, 4−14C1/4/, /2-thiol[35S]/

A synthesis of¹⁴C and³⁵S double labelled hexylthiols: C₆H₁₃SH–1/1, 2, 3, 4–¹⁴C_1/4/, /1-thiol[³⁵S]/ and C₆H₁₃SSH–2/1, 2, 3, 4–¹⁴C_1/4/, /2-thiol[³⁵S]/ based on H₂ ³⁵S and C₆H₁₂–/1, 2, 3, 4–¹⁴C_1/4/ has been developed and described.     

EPR study of the rearrangement of (C2H5)3SiCH2CH2ĊCl2 radicals

Conclusions It has been established that the rearrangement of (C₂H₅)₃Si(CH₂)₂Cl₂ radicals into (C₂H₅)₂Si(CH₃CH)(CH₂)₂CCl₂H takes place by an intramolecular mechanism with 1,5-migration of a hydrogen atom. The rate constant for the isomerization has been determined at 20°C and found to be (2.2 ± 0.3)·10³ sec^–1.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2512–2516, November, 1988.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

The mutual diffusion coefficients of Na2SO4−H2O and MgSO4−H2O at 25°C from Rayleigh interferometry

The volume-fixed mutual diffusion coefficients of Na₂SO₄–H₂O and MgSO₄–H₂O have been measured, from dilute solutions to near saturation, to an accuracy of 0.1–0.2% by free-diffusion Rayleigh interferometry. These results are compared to other available diffusion data for these salts. The diffusion coefficients of Na₂SO₄–H₂O and MgSO₄–H₂O decrease regularly with increasing concentration, while those of many other salts exhibit both a maximum and a minimum as a function of concentration. A few diffusion coefficients have also been measured for KCl–H₂O.Reference to a company or product names does not imply approval or recommendation of the product by the University of California or the U.S. Department of Energy to the exclusion of others that may be suitable.This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Department of Energy, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.University of Illinois at Urbana-Champaign; tenure served as a participating guest at Lawrence Livermore Laboratory.     

Die Kristallstruktur von Tetrachloräthylencarbonat—Antimon(V)-chlorid,C2Cl4O2CO·SbCl5

Zusammenfassung Die Kristallstruktur des Adduktes Tetrachloräthylencarbonat—Antimon(V)-chlorid, C₂Cl₄O₂CO·SbCl₅ wurde mit Hilfe der Schweratom-Methode aus dreidimensionalen Röntgendaten bestimmt und nach der Methode der kleinsten Quadrate bis zu einemR-Wert von 13,1% verfeinert (Raumgruppe P2₁/n — Nr. 14;a=10,13,b=12,15 undc=12,55 Å, =108°40). Die Elementarzelle enthält 4 Moleküle C₂Cl₄O₂CO· SbCl₅. Das Antimonatom ist oktaedrisch von 5 Chloratomen und dem Carbonylsauerstoffatom des Tetrachloräthylencarbonats umgeben (Sb–Cl 2,28–2,33 und Sb–O 2,40 Å).

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The crystal structure of tetrachloroethylene carbonate antimony(V) chloride, C₂Cl₄O₂CO·SbCl₅

The crystal structure of the adduct tetrachloroethylene carbonate antimony(V)-chloride, C₂Cl₄O₂CO·SbCl₅, has been determined by the heavy-atom method from three-dimensional X-ray data. The refinement of the parameters was carried out by least-squares resulting anR-value of 13.1% (space group P2₁/n — No. 14;a=10.13,b=12.15 andc=12.55 Å, =108°40). The unit cell contains 4 discrete molecules C₂Cl₄O₂CO·SbCl₅. The antimony atom is coordinated octahedrally by 5 chlorine atoms and the carbonyl oxygen atom of tetrachloroethylene carbonate (Sb–Cl 2.28–2.33 and Sb–O 2.40 Å).

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Mit 2 Abbildungen     

The outersphere complex of EuCl2+ in a mixed system of methanol and water of 1.0M (H, Na) (Cl, ClO4)

The stability constans, ₁, of each monochloride complex of Eu(III) have been determined in the methanol and water mixed system with 1.0 mol·dm^–3 ionic strength using a solvent extraction technique. The values of ₁ increase with an increase in the mole fraction of methanol (X _S ) in the mixed solvent system when 0X _S 0.40. The, distance of Eu³⁺–Cl^– in the mixed solvent system was calculated using the Born-type equation and the Gibbs' free energy derived from ₁. Calculation of the Eu³⁺–Cl^– distance and the preferential solvation, of Eu³⁺ by water proposed the variation of the outersphere complex of EuCl²⁺ as follows: (1) [Eu(H₂O)₉]³⁺Cl^–, [Eu(H₂O)₈]³⁺Cl^– and [Eu(H₂O)₇(CH₃OH)³⁺Cl^– inX _S0.014, (2) [Eu(H₂O)₈]^3–Cl^– and [Eu(H₂O)₇(CH₃OH)]³⁺Cl^– in 0.014<X _S <0.25 and (3) [Eu(H₂O)₇(CH₃OH)]^3–Cl^– and [Eu(H₂O)₆(CH₃OH)[₂ ³⁺Cl^– in 0.25<X _S 0.40.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–KCl–H2O at 25°C

Relative humidities have been measured for mixed aqueous electrolyte system of ammonium and potassium chlorides by the hygrometric method at total molalities from 0.3 to 6 mol-kg^–1for ionic-strength fractions yof NH₄Cl of 1/3, 1/2, and 2/3 at 25°C. The data allow the calculation of new water activities and osmotic coefficients. The proposed ECA (extended composed additivity) rule of calculation of water activity in mixed aqueous electrolyte solutions from the water activities of a single component is extended to this system. The experimental results and the predictions of the ECA rule are compared with the Robinson–Stokes, Reilly–Wood–Robinson, the Pitzer, and the Lietzke–Stoughton II models. Predictions made using these models are, in general, consistent with our results. From these measurements, the Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

Synthesis and structure of anilinium chloranilate (NH3C6H5)2 · (C6O4C12) and acid ammonium chloranilate dihydrate NH4H5O2(C6O4Cl2)

Conclusions The authors have synthesized anilinium chloranilate (NH₃C₆H₅)₂(C₆O₄Cl₂) (I) and acid ammonium chloranilate dihydrate NH₄H₅O₂(C₆O₄C1₂) (II). By x-ray structural analysis they have established their crystal structures. In crystals of NH₄H₅O₂(C₆O₄Cl₂) they find the ion H₅O ₂ ⁺ with the unusual O-H-O bond length of 2.81 A. The anions of chloranilic acid in crystals (I) and (II) have equal charges but different structures.Translated from IzvestiyaAkademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 487–489, March, 1981.     

Acidity function scale for H2SO4 solutions in phenol-acetone solvents with low water content at 25°C

The indicator method was employed to measure the acidity function H ₀ ^S of H₂SO₄ solutions in solvents consisting of an equimolar mixture of phenol and acetone with 0.8% water (from 3.6·10^–4 to 2.6·10^–2 M H₂SO₄) and 2.5% water (from 4.3·10^–4 to 0.32 M H₂SO₄) and of phenol and acetone in a molar ratio of 1:1.5 with 0.67% water (from 1.63·10^–4 to 7.77·10^–2 M H₂SO₄) and 2.09% water (from 4.49·10^–4 to 0.35 M H₂SO₄) at 25°C. The indicators employed were 4- and 2-nitroaniline.Deceased.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Lenneftekhim Scientific-Commercial Association, St. Petersburg. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 72–78, January, 1992.     

Tailoring a robust Al-MOF for trapping C2H6 and C2H2 towards efficient C2H4 purification from quaternary mixtures

Light hydrocarbon separation is considered one of the most industrially challenging and desired chemical separation processes and is highly essential in polymer and chemical industries. Among them, separating ethylene (C₂H₄) from C2 hydrocarbon mixtures such as ethane (C₂H₆), acetylene (C₂H₂), and other natural gas elements (CO₂, CH₄) is of paramount importance and poses significant difficulty. We demonstrate such separations using an Al-MOF synthesised earlier as a non-porous material, but herein endowed with hierarchical porosity created under microwave conditions in an equimolar water/ethanol solution. The material possessing a large surface area (793 m² g⁻¹) exhibits an excellent uptake capacity for major industrial hydrocarbons in the order of C₂H₂ > C₂H₆ > CO₂ > C₂H₄ > CH₄ under ambient conditions. It shows an outstanding dynamic breakthrough separation of ethylene (C₂H₄) not only for a binary mixture (C₂H₆/C₂H₄) but also for a quaternary combination (C₂H₄/C₂H₆/C₂H₂/CO₂ and C₂H₄/C₂H₆/C₂H₂/CH₄) of varying concentrations. The detailed separation/purification mechanism was unveiled by gas adsorption isotherms, mixed-gas adsorption calculations, selectivity estimations, advanced computer simulations such as density functional theory (DFT), grand canonical Monte Carlo (GCMC) and ab initio molecular dynamics (AIMD), and stepwise multicomponent dynamic breakthrough experiments.

Industrially important C₂H₄ purification from multi-component hydrocarbon mixtures.     

Sensing the ortho Positions in C6Cl6 and C6H4Cl2 from Cl2− Formation upon Molecular Reduction

The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl₂⁻. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using ortho-, meta- and para-dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations. We also observed that Cl₂⁻ formation can only occur in 1,2-C₆H₄Cl₂, where the two closest C–Cl bonds are cleaved while the chlorine atoms are brought together within the ring framework due to excess energy dissipation. These results show that a strong coupling between electronic and C–Cl bending motion is responsible for a positional isomeric effect, where molecular recognition is a determining factor in chlorine anion formation.     

Ab initio calculations ofp-Cl2C6H4 molecule and its35Cl NQR parameters

Ab initio calculations ofp-dichlorobenzene molecule were carried out using the Hartree-Fock method in the 6–31 G* valence-split basis set. The molecule was also calculated by the MNDO method in the valence sp-basis set for comparison. The populations of the valent p-orbitals of the C and CI atoms were analyzed. The optimized geometry of the molecule as well as its³⁵Cl NQR frequency and the asymmetry parameter of the electric field gradient at the³⁵CI nuclei calculated using the populations of the less diffuse components of the valent p-orbitals of the Cl atoms are in agreement with the corresponding experimental values for the -modification of 1,4-Cl₂C₆H₄.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2177–2179, September, 1996.     

Hygrometric Determination of Water Activities and Osmotic and Activity Coefficients of NH4Cl–LiCl–H2O at 25°C

The mixed aqueous electrolyte system of ammonium and lithium chlorides has been studied by the hygrometric method at 25°C. The relative humidities of this system are measured at total molalities from 0.3 to 6 mol-kg^{– 1} for different ionic-strength fractions y of NH₄Cl with y = 0.33, 0.50, and 0.67. The data obtained allow the deduction of new water activities and osmotic coefficients. The experimental results are compared with the predictions of the ECA (extended composed additivity) law proposed in our previous work. The Zdanovskii–Stokes–Robinson (ZSR), the Robinson–Stokes (RS), Reilly–Wood–Robinson (RWR), the Pitzer, and the Lietzke–Stoughton (LS II) models are also compared with our results. Predictions made using these models are, in general, consistent with our results. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture for different ionic-strength fractions.     

An aqueous thermodynamic model for a high valence 4∶2 electrolyte Th4+−SO 4 2− in the system Na+−K+−Li+−NH 4 + −Th4+−SO 4 2− −HSO 4 − −H2O to high concentration

An aqueous thermodynamic model that is valid from zero to high concentration is proposed for the Na⁺–K⁺–Li⁺–NH ₄ ⁺ –Th⁴⁺–SO ₄ ^2– –HSO ₄ ^– –H₂O system. The model is based on the aqueous ion-interaction model of Pitzer and coworkers. The thorium sulfate complex species Th(SO₄)₂(aq) and Th(SO₄) ₃ ^2– are also included in the model. The final thermodynamic model presented here accurately predicts all reliable thermodynamic data, including solvent extraction and solubility data, for the Na⁺–K⁺–Li⁺–NH ₄ ⁺ –Th⁴⁺–SO ₄ ^2– –HSO ₄ ^– –H₂O system to high concentration. The aqueous thermodynamics of high-valence (3:2, 4:2), electrolytes are complicated by very strong specific ion interactions or ion pairing in dilute solution and by an effective redissociation of aqueous complex species at high concentration. Methods of treating these complications, in terms of valid aqueous thermodynamic models, are discussed in detail for the high-valence Th⁴⁺–SO ₄ ^2– –H₂O system.     

Raman and infrared spectra of6Li2C2O4 and7Li2C2O4

Raman and infrared spectra of polycrystalline⁶Li₂C₂O₄ and⁷Li₂C₂O₄ have been investigated in the wavenumber region from 1,800 to 40 cm^–1. The internal C₂O₄ ^–2 vibrations have been studied on the basis of a D_2h molecular structure and the correlation field splittings have been found to be about 40 cm^–1 for the stretching modes and about 15 cm^–1 for the bending modes. The external vibrations of the Li⁺ and C₂O₄ ^–2 sites have been discussed by considering the results of the factor group analysis and the⁶Li/⁷Li isotope effect on the normal vibrations.

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Raman- und Infrarot-Spektren von⁶Li₂C₂O₄ und⁷Li₂C₂O₄

Zusammenfassung Es wurdenRaman- und IR-Spektren von polykristallinem⁶Li₂C₂O₄ und⁷Li₂C₂O₄ im Bereich der Wellenzahlen von 1800 bis 40 cm^–1 untersucht. Die internen Schwingungen wurden auf der Basis einer D_2h Molekülstruktur analysiert. Für die Streckschwingungen wurde eine Korrelationsaufspaltung von etwa 40 cm^–1 gefunden, für die Deformationsschwingungen etwa 15 cm^–1. Die Diskussion der externen Schwingungen von Li⁺ und C₂O₄ ^–2 erfolgte unter Berücksichtigung der Resultate der Faktorgruppenanalyse und des⁶Li/⁷Li Isotopeneffekts auf die Normalschwingungen.

     

Comparison of Properties of Carbon Particles Formed by Pyrolysis of C3O2 and C2H2 behind Shock Waves

Various carbon particles formed by the pyrolysis of C₃O₂ and C₂H₂ behind shock waves in the temperature range 1200–3800 K are studied. The formation of the condensed carbon particles is observed directly by the multichannel detection of the time profiles of the extinction of the medium in the UV, visible, and near-IR spectral regions. The samples of carbon material deposited on the walls of a shock tube after an experiment are analyzed using transmission electron microscopy with different resolutions and electron microdiffraction. Particles formed from C₃O₂ and C₂H₂ at 1500–2000 K are 10–30 nm in size and look like usual soot. The absence of molecular hydrogen in C₃O₂ only results in faster formation and graphitization. At 2100–2600 K, the formation of particles is retarded, and the yield of the carbon particles decreases for both substances. After experiments on pyrolysis of C₃O₂ at these temperatures, giant spherical particles up to 700 nm in size are found on the walls of the shock tube. Carbon particles formed at the highest temperatures (2700–3200 K) in C₃O₂ pyrolysis have the high degree of crystallinity of particles.     

A population analysis of the bonding in N2O4, B2Cl4, B2F4, C2H4 and C3H4

Population matrices have been calculated from molecular orbital wave functions of N₂O₄, B₂Cl₄, and B₂F₄ in order to understand further the bonding in these molecules which are isoelectronic in valence electrons but different in structure. C₂H₄ and C₃H₄ have been included in this study as check cases.

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Zusammenfassung Ausgehend von Molekülorbitalen werden Besetzungsmatrizen für N₂O₄, B₂Cl₄ und B₂F₄ berechnet, um die Bindung in diesen Molekülen, die in den Valenzelektronen isoelektronisch sind, aber unterschiedliche Strukturen aufweisen, besser zu verstehen. C₂H₄ und C₃H₄ sind in dieser Untersuchung als Prüffälle eingeschlossen.

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Résumé Des matrices d'occupation ont été calculées à partir des orbitales moléculaires de N₂O₄, B₂Cl₄ et B₂F₄, afin de comprendre plus profondément la liaison dans ces molécules, qui sont isoélectroniques par leurs électrons de valence, mais qui n'ont pas la même structure. C₂H₄ et C₃H₄ sont considérés dans cette étude à titre de vérification.