Sample records for 1,2-dimethoxyethane

  1. Conformation of 1,2-Dimethoxyethane in Water

    Institute of Scientific and Technical Information of China (English)


    To understand the conformation of 1,2-dimethoxyethane (DME) in water, a system of two kinds of molecules, DME and H2O, was focused. The interaction of various conformers of DME with water was studied by means of ab initio molecular orbital calculation with 6-31G(d)basis set. It is shown that there are two forms of interactions between the two molecules in the sys tem, the close touched (H2O attaches to the two oxygen atoms of DME) and the open touched (H2O attaches to one oxygen atom of DME) structures. The conformation of DME is remark ably influenced by the interactions. Instead the ttt conformer is preferred in the gas state, with a close touched H2O the tgt conformer becomes the most stable one. The obtained hydration ener gies show that the stabilized order of DME conformers by water is tgt>tgg'>ttt.

  2. Tris(1,2-dimethoxyethane-κ2O,O′iodidocalcium iodide

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    Siou-Wei Ou


    Full Text Available In the title complex, [CaI(C4H10O23]I, the CaII atom is seven-coordinated by six O atoms from three 1,2-dimethoxyethane (DME ligands and one iodide anion in a distorted pentagonal–bipyramidal geometry. The I atom and one of the O atoms from a DME ligand lie in the axial positions while the other O atoms lie in the basal plane. The other iodide anion is outside the complex cation.

  3. A synthesis of crystalline Li7P3S11 solid electrolyte from 1,2-dimethoxyethane solvent (United States)

    Ito, Seitaro; Nakakita, Moeka; Aihara, Yuichi; Uehara, Takahiro; Machida, Nobuya


    A crystalline solid electrolyte, Li7P3S11, was synthesized by a liquid-phase reaction of Li2S and P2S5 in an organic solvent. A precursor, which was a mixture of solvated Li3PS4 and Li4P2S7, was prepared by mixing Li2S and P2S5 powders in 1,2-dimethoxyethane (DME) solvent. After a vacuum drying of the precursor, the crystalline phase of Li7P3S11 was obtained by heat treatment at 250 °C for 1 h in Ar atmosphere. The Li7P3S11 sample showed high ionic conductivity of 2.7 × 10-4 S cm-1 at room temperature. The liquid-phase synthesis of the solid electrolyte has advantages for mass-production of all-solid-state batteries.

  4. Association constants in solutions of lithium salts in butyrolactone and a mixture of propylene carbonate with 1,2-dimethoxyethane (1 : 1), according to conductometric data (United States)

    Chernozhuk, T. V.; Sherstyuk, Yu. S.; Novikov, D. O.; Kalugin, O. N.


    A conductometric study is performed with solutions of lithium bis(oxalato)borate (LiBOB) in γ-butyrolactone (γ-BL) at 278.15-388.15 K and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), LiBOB, and lithium tetrafluoroborate (LiBF4) in mixtures of propylene carbonate and 1,2-dimethoxyethane (PC + 1,2-DME) (1 : 1) at 278.15-348.15 K. Limiting molar electrical conductivities (LMECs) and association constants ( K a) in the studied solutions of electrolytes are determined using the Lee-Wheaton equation. The effect temperature, the nature of the solvent, and the properties of the anion have on the conductivity and interparticle interactions in solutions of lithium salts in γ-BL and PC + 1,2-DME (1 : 1) is established. It was concluded that the studied solutions are characterized by low values of their association constants. It was found that the BOB;- anion destroys the structure of the solvent.The thickness of the dynamic solvation shell of ions (Δ R) remains constant for both solvents over the studied range of temperatures, and Δ R is significantly greater for Li+ than for other ions.

  5. Organoamido- and aryloxo-lanthanoids, 19. synthesis and structures of cisoid and transoid bis(1,2-dimethoxyethane)bis({eta}{sup 2}-pyrazolato)lanthanoid(II) complexes

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    Deacon, G.B.; Delbridge, E.E. [Monash Univ., Clayton (Australia). Dept. of Chemistry; Skelton, B.W.; White, A.H. [Western Australia Univ., Nedlands, WA (Australia). Dept. of Chemistry


    The complexes [Yb(bind){sub 2}(DME){sub 2}], [Yb(MePhpz){sub 2}(DME){sub 2}], [Yb(azin){sub 2}(DME{sub 2})], and [Eu(Ph{sub 2}pz){sub 2}(DMe){sub 2}] (bindH=4.5-dihydro-2H-benz[g]indazole; MePhpzH=3-methyl-5-phenylpyrazole; azinH=7-azaindole; Ph{sub 2}pzH=3,5-dephenylpyrazole; DME=1,2-dimethoxyethane) have been prepared by redox transmetallation between ytterbium or europium metal and the corresponding thallium(I) pyrazolate in tetrahydrofuran (THF) in the presence of mercury metal, followed by work up with DME. The thallium reagents were obtained by treatment of the appropriate pyrazole with thallium(I) ethoxide. Both [Yb(Ph{sub 2}pz){sub 2}(DME){sub 2}] and [Sm(Ph{sub 2}pz){sub 2}(DME){sub 2}] have been prepared by metathesis from LnI{sub 2}(THF){sub 2} and K(Ph{sub 2}pz) in THF, whilst the former has also been obtained by redox transmetallation from [Hg(Ph{sub 2}pz){sub 2}] and ytterbium metal and by reaction of 3,5-diphenylpyrazole with Yb(C{sub 6}F{sub 5}){sub 2}, and the latter from protolysis of [Sm{l_brace}N(SiMe{sub 3}){sub 2}{r_brace}{sub 2}(THF){sub 2}] with Ph{sub 2}pzH, followed in each case by crystallisation of the crude product from DME. Europium(II) 3,5-di-tert-butylpyrazolate was synthesised by a redox transmetallation/ligand exchange reaction between europium metal chunks, diphenylmercury(II), and 3,5-ditert-butylpyrazole (tBu{sub 2}pzH) in the presence of mercury metal in THF, and [Eu(tBu{sub 2}pz){sub 2}(DME){sub 2}] was isolated on crystallisation of the crude product from DME. The X-ray crystal structures of [Ln(L){sub 2}(DME){sub 2}] (Ln=Yb, L=bind or azin; Ln=Eu or Sm, L=Ph{sub 2}pz; Ln=Eu, L=tBu{sub 2}pz), each of a different crystallographic form, reveal eight-coordinate lanthanoid complexes with two {eta}{sup 2}-pyrazolate and two chelating DME ligands, but the structures differ in the relationship (cisoid or transoid) between the pyrazolate ligands. Thus cen-Ln-cen (cen=centre of the N-N bond) angles of 106.7 [Yb(bind){sub 2}(DME){sub 2

  6. On the reduced Redlich-Kister excess properties for 1,2-dimethoxyethane with propylene carbonate binary mixtures at temperatures (from 298.15 to 318.15 K.

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    Hanen Salhi


    Full Text Available Values of excess properties in 1,2-dimethoxyethane + propylene carbonate binary liquid mixtures at different temperatures from experimental density and viscosity values presented in earlier work, were used to test the applicability of the correlative reduced Redlich-Kister functions and the Belda equation, and to reveal eventual specific interaction hidden by the classical treatment of direct excess Redlich-Kister functions. Their correlation ability at different temperatures, and the use of different numbers of parameters, is discussed for the case of limited experimental data. The relative Redlich-Kister functions are important to reduce the effect of temperature and, consequently, to reveal the effects of different types of interactions. Values of limiting excess partial molar volume at infinite dilution deduced from different methods were discussed. Also, the activation parameters and partial molar Gibbs free energy of activation of viscous flow against compositions were investigated. Correlation between the two Arrhenius parameters of viscosity shows the existence of main different behaviors separated by a stabilized structure in a short range of mole fraction in 1,2-dimethoxyethane (0.45 to 0.83. In this context, the correlation Belda equation has also been applied to the present system for thermodynamic properties in order to reveal eventual solute-solvent interaction at high dilution.

  7. Tetrakis(1,2-dimethoxyethane-κ2O,O′ytterbium(II bis(μ2-phenylselenolato-κ2Se:Sebis[bis(phenylselenolato-κSemercurate(II

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    Michael D. Romanelli


    Full Text Available The title salt, [Yb(C4H10O24][Hg2(C6H5Se6], consists of eight-coordinate homoleptic [Yb(DME4]2+ dications (DME is 1,2-dimethoxyethane countered with [Hg2(SePh6]2− dianions. The cations and anions have twofold rotation and inversion symmetry, respectively. The Yb centre displays a square-antiprismatic coordination geometry and the Hg centre has a distorted tetrahedral coordination environment. One phenylselenolate anion and one methyl group of a DME ligand are disordered over two positions with equal occupancies. This structure is unique in that it represents a less common molecular lanthanide species in which the lanthanide ion is not directly bonded to an anionic ligand. There are no occurrences of the [Hg2(SePh6]2− dianion in the Cambridge Structural Database (Version of November 2007, but there are similar oligomeric and polymeric Hgx(SePhy species. The crystal structure is characterized by alternating layers of cations and anions stacked along the c axis.

  8. Thermodynamics of Dimerization of Lithium Salts in 1,2 Dimethoxyethane. (United States)


    conductance methods. LiBF4 , another electrolyte relevant to a battery construction, has now been investigated by the same methods in 1, Z-DME in order...dielectric and conduc- tance work have been described elsewhere [3 1. LiBF4 (Aldrich) was re- dried in vacuo (- 1 torr) at - 70 0 C overnight. 1, 2-DME has...imaginary part e ’ and e" of the complex permittivity = el-J e, plotted vs. the frequency-f for a representative concentration of LiBF4 in 1, 2-DME at 25 0

  9. Natural Abundance 17O, 6Li NMR and Molecular Modeling Studies of the Solvation Structures of Lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane Liquid Electrolytes

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    Wan, Chuan; Hu, Mary Y.; Borodin, Oleg; Qian, Jiangfeng; Qin, Zhaohai; Zhang, Jiguang; Hu, Jian Z.


    Natural abundance 17O and 6Li NMR experiments, quantum chemistry and molecular dynamics studies were employed to investigate the solvation structures of Li+ at various concentrations of LiFSI in DME electrolytes in an effort to solve this puzzle. It was found that the chemical shifts of both 17O and 6Li changed with the concentration of LiFSI, indicating the changes of solvation structures with concentration. For the quantum chemistry calculations, the coordinated cluster LiFSI(DME)2 forms at first, and its relative ratio increases with increasing LiFSI concentration to 1 M. Then the solvation structure LiFSI(DME) become the dominant component. As a result, the coordination of forming contact ion pairs between Li+ and FSI- ion increases, but the association between Li+ and DME molecule decreases. Furthermore, at LiFSI concentration of 4 M the solvation structures associated with Li+(FSI-)2(DME), Li+2(FSI-)(DME)4 and (LiFSI)2(DME)3 become the dominant components. For the molecular dynamics simulation, with increasing concentration, the association between DME and Li+ decreases, and the coordinated number of FSI- increases, which is in perfect accord with the DFT results. These results provide more insight on the fundamental mechanism on the very high CE of Li deposition in these electrolytes, especially at high current density conditions.

  10. The effect of 1,2-dimethoxyethane on the storage and performance of lithium cells with MnO 2 and (CF) n cathodes (United States)

    Fr açkowiak, E.; Kuksenko, S.

    The characteristics of lithium cells with MnO 2 and (CF) n cathodes were investigated for two different electrolyte compositions, i.e., LiClO 4/PC+DME and LiClO 4/PC. For such lithium cells, the greater loss of long-term storage capacity was found in the case of cells using mixed PC+DME electrolyte. The oxidation process of DME by the cathode elements during the storage period is assumed to be the cause of the capacity loss. In the case of cells using MnO 2 as a cathode, the polymerisation process of the oxidation products of DME on the cathode surface can be also considered. After storage at 45°C, the smaller loss of capacity was found for the cells using MnO 2 as a cathode. The different behaviour of these two kinds of cells during a pulse discharge was also confirmed.

  11. [N,N′-Bis(2,6-diisopropylphenylpentane-2,4-diamine(1–-2κ2N,N′]-μ2-chlorido-1:2κ2Cl:Cl-chlorido-2κCl-bis(1,2-dimethoxyethane-1κ2O,O′iron(IIlithium

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    Rafał Grubba


    Full Text Available In the title compound, [FeLi(C29H41N2Cl2(C4H10O22], the FeII atom is coordinated by two N and two Cl atoms, generating a distorted FeN2Cl2 tetrahedral geometry. Additionally, one of the chloride atoms bridges to a lithium ion, which is solvated by two dimethoxyethane molecules and is coordinated in a distorted trigonal-bipyramidal environment. The central Fe, Cl (× 2 and Li atoms are coplanar with a maximum deviation of 0.034 Å.

  12. Thermoelectric Properties of Cobalt Triantimonide (CoSb3) Prepared by an Electrochemical Technique (United States)


    used as the anode. The electrolyte was 1 M lithium tetrafluoroborate ( LiBF4 ) in a 1:1 (wt.%) mixture of propylene carbonate (PC) and 1, 2...cobalt triantimonide DME 1,2-dimethoxyethane DSC differential scanning calorimetry Ge germanium Li lithium LiBF4 lithium tetrafluoroborate

  13. Stereoretentive Addition of N-tert-Butylsulfonyl-α-Amido Silanes to Aldehydes, Ketones, α,β-Unsaturated Esters, and Imines. (United States)

    Mita, Tsuyoshi; Saito, Keisuke; Sugawara, Masumi; Sato, Yoshihiro


    Enantioenriched N-tert-butylsulfonyl-α-amido silanes were successfully reacted with aldehydes, ketones, imines, and α,β-unsaturated esters in the presence of a sub-stoichiometric amount of CsF (0.5 equiv) in 1,2-dimethoxyethane (DME) at -20 °C to afford the corresponding coupling products with up to 89 % enantiospecificity in a retentive manner.

  14. A Survey of Low-Temperature Operational Boundaries of Navy and Marine Corps Lithium and Lithium-Ion Batteries (United States)


    from 0°C → –20°C decreases the Li+ diffusivity); and (iii) sluggish charge-transfer kinetics at the active electrodes. These low- temperature...that of the Li/Li+ redox potential. As the temperature is lowered and lithium transport and reaction kinetics at the graphite anode become slower...low temperatures The Li–MnO2 D-size cells use tetrahydrofuran (THF), propylene carbonate (PC), and 1,2- dimethoxyethane ( DME ) as the solvent

  15. [N,N-Bis(diphenylphosphinoisopropylamine]dibromidonickel(II

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    Full Text Available The title compound, [NiBr2(C27H27NP2], was synthesized by the reaction of NiBr2(dme (dme is 1,2-dimethoxyethane with N,N-bis(diphenylphosphinoisopropylamine in methanol/tetrahydrofuran. The nickel(II center is coordinated by two P atoms of the chelating PNP ligand, Ph2PN(iPrPPh2, and two bromide ions in a distorted square-planar geometry.

  16. Lithium ion transport in a model of amorphous polyethylene oxide.

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    Boinske, P. T.; Curtiss, L.; Halley, J. W.; Lin, B.; Sutjianto, A.; Chemical Engineering; Univ. of Minnesota


    We have made a molecular dynamics study of transport of a single lithium ion in a previously reported model of amorphous polyethylene oxide. New ab initio calculations of the interaction of the lithium ion with 1,2-dimethoxyethane and with dimethyl ether are reported which are used to determine force fields for the simulation. We report preliminary calculations of solvation energies and hopping barriers and a calculation of the ionic conductivity which is independent of any assumptions about the mechanism of ion transport. We also report some details of a study of transport of the trapped lithium ion on intermediate time and length scales.

  17. Study of Uranium Oxide Insertion Compounds (United States)


    05 0-6 0-7 08 0.9 x in LiU03 Figure 1.6 Equilibrium discharge curve for lithium insertion into Y-U0 3 at approximately 25’C in 1 M LiBF4 in propylene...insertion into a-U 30 8 at - 25"C in 1M LiBF4 in propylene carbonate/1,2- dimethoxyethane Lithium insertion into a-U 30 8 causes very little change in

  18. Rechargeable lithium batteries based on Li{sub 1+x}V{sub 3}O{sub 8} thin films

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    Bonino, F. [Dept. of Chemistry, Rome Univ. `La Sapienza` (Italy); Panero, S. [Dept. ICMMPM, Rome Univ. `La Sapienza` (Italy); Pasquali, M. [Dept. ICMMPM, Rome Univ. `La Sapienza` (Italy); Pistoia, G. [Centro di Studio per l`Elettrochimica e la Chimica Fisica delle Interfasi, CNR, Rome (Italy)


    Low-temperature thin films of Li{sub 1+x}V{sub 3}O{sub 8} have been fabricated and tested in LiClO{sub 4}/propylene carbonate-1,2-dimethoxyethane/Li cells. These cells show very good intercalation kinetics, and at 0.4 C discharge rate produce a specific energy of {approx}110 Wh/kg. The films could be used in microbatteries for electronic devices, and applications requiring more power could also be envisaged. (orig.)

  19. Cathode including a non fluorinated linear chain polymer as the binder, method of making the cathode, and lithium electrochemical cell containing the cathode (United States)

    Plichta, Edward J.; Salomon, Mark


    A cathode suitable for use in a lithium electrochemical cell is made from a mixture of active cathode material, carbon, and non fluorinated linear chain polymer by a method including the following steps: (1) dissolving the non fluorinated linear polymer in a non polar solvent at a temperature near the melting point of the polymer; (2) adding the active cathode material and carbon and evaporating the solvent; and (3) grinding the dried mixture into a fine powder and making it into a cathode by pressing the powdered mixture onto both sides of an expanded metal screen and then cutting to the desired dimensions. The cathode can be combined with lithium as the anode and a solution of 0.8 mol/cu dm LiAlCl4 in a mixed organic solvent of 24 mass percent 4-butyrolactone in 1, 2 dimethoxyethane as the electrolyte to provide a mechanically stable, relatively inexpensive lithium electrochemical cell having good cell performance.

  20. Highly volatile magnesium complexes with the aminodiboranate anion, a new chelating borohydride. Synthesis and characterization of Mg(H(3)BNMe(2)BH(3))(2) and related compounds. (United States)

    Kim, Do Young; Girolami, Gregory S


    Remarkably volatile magnesium complexes have been prepared with the modified borohydride ligand N,N-dimethylaminodiboranate, H(3)BNMe(2)BH(3)(-). The homoleptic complex Mg(H(3)BNMe(2)BH(3))(2), its monoadducts with tetrahydrofuran and 1,2-dimethoxyethane, and the mixed ligand complex (C(5)Me(5))Mg(H(3)BNMe(2)BH(3))(thf) have been prepared. The homoleptic complex Mg(H(3)BNMe(2)BH(3))(2) has a vapor pressure of 800 mTorr at 25 degrees C, which makes it the most volatile magnesium complex known. Crystal structures and NMR data are reported for all complexes. The compounds are potentially useful as chemical vapor deposition precursors to MgB(2) and MgO, and as hydrogen storage materials.

  1. Growth inhibition to enhance conformal coverage in thin film chemical vapor deposition. (United States)

    Kumar, Navneet; Yanguas-Gil, Angel; Daly, Scott R; Girolami, Gregory S; Abelson, John R


    We introduce the use of a growth inhibitor to enhance thin film conformality in low temperature chemical vapor deposition. Films of TiB(2) grown from the single source precursor Ti(BH(4))(3)(dme) are much more highly conformal when grown in the presence of one of the film growth byproducts, 1,2-dimethoxyethane (dme). This effect can be explained in terms of two alternative inhibitory mechanisms: one involving blocking of surface reactive sites, which is equivalent to reducing the rate of the forward reaction leading to film growth, the other analogous to Le Chatelier's principle, in which the addition of a reaction product increases the rate of the back reaction. The reduction in growth rate corresponds to a reduction in the sticking probability of the precursor, which enhances conformality by enabling the precursor to diffuse deeper into a recessed feature before it reacts.

  2. Direct Conversion of Mono- and Polysaccharides into 5-Hydroxymethylfurfural Using Ionic-Liquid Mixtures. (United States)

    Siankevich, Sviatlana; Fei, Zhaofu; Scopelliti, Rosario; Jessop, Philip G; Zhang, Jiaguang; Yan, Ning; Dyson, Paul J


    Platform chemicals are usually derived from petrochemical feedstocks. A sustainable alternative commences with lignocellulosic biomass, a renewable feedstock, but one that is highly challenging to process. Ionic liquids (ILs) are able to solubilize biomass and, in the presence of catalysts, convert the biomass into useful platform chemicals. Herein, we demonstrate that mixtures of ILs are powerful systems for the selective catalytic transformation of cellulose into 5-hydroxymethylfurfural (HMF). Combining ILs with continuous HMF extraction into methyl-isobutyl ketone or 1,2-dimethoxyethane, which form a biphase with the IL mixture, allows the online separation of HMF in high yield. This one-step process is operated under relatively mild conditions and represents a significant step forward towards sustainable HMF production.

  3. Concept for enhancement of the stability of calcium-bound pyrazolyl-substituted methanides. (United States)

    Müller, Christoph; Krieck, Sven; Görls, Helmar; Westerhausen, Matthias


    Metalation of bis(3-thiophen-2-ylpyrazol-1-yl)phenylmethane [2, which is accessible from the reaction of bis(3-thien-2-ylpyrazol-1-yl)methanone (1) with triphosgene] with [(thf)2Ca{N(SiMe3)2}2] in tetrahydrofuran and subsequent crystallization from a mixture of toluene and 1,2-dimethoxyethane yield [(dme)Ca{C(Pz(th))2Ph}{N(SiMe3)2}] (3). The α,α-bis(3-thiophen-2-ylpyrazol-1-yl)benzyl ligand exhibits a κ(2)N,κC-coordination mode with a Ca-C σ-bond length of 262.8(2) pm. The crystalline compound is stable if air and moisture is strictly excluded; however, in solution; this calcium complex slowly degrades.

  4. A Polarizable Potential for Poly(ethylene oxide) in Aqueous Solution (United States)

    Starovoytov, Oleg; Borodin, Oleg; Bedrov, Dmitry; Smith, Grant


    We have developed a quantum chemistry-based polarizable potential for poly(ethylene oxide) (PEO) in aqueous solution based on the APPLE&P polarizable ether and SWM4-DP polarizable water model. Ether-water interactions were parameterized to reproduce the binding energy of water with 1,2-dimethoxyethane (DME) determined from high-level quantum chemistry calculations. Simulations of DME/water and PEO/water solutions at room temperature using the new polarizable potential yielded thermodynamic and transport properties in better agreement with experiment than previously published polarizable and non-polarizable potentials. The predicted miscibility of PEO and water as a function of temperature was found to be strongly correlated with the predicted free energy of solvation of DME in water for the various force fields investigated. Simulations of PEO/water solutions confirm the ability of the new potential to capture, at least qualitatively, the LCST behavior of these solutions

  5. Development of a Polarizable Force Field for Molecular Dynamics Simulations of Poly (Ethylene Oxide) in Aqueous Solution. (United States)

    Starovoytov, Oleg N; Borodin, Oleg; Bedrov, Dmitry; Smith, Grant D


    We have developed a quantum chemistry-based polarizable potential for poly(ethylene oxide) (PEO) in aqueous solution based on the APPLE&P polarizable ether and the SWM4-DP polarizable water models. Ether-water interactions were parametrized to reproduce the binding energy of water with 1,2-dimethoxyethane (DME) determined from high-level quantum chemistry calculations. Simulations of DME-water and PEO-water solutions at room temperature using the new polarizable potentials yielded thermodynamic properties in good agreement with experimental results. The predicted miscibility of PEO and water as a function of the temperature was found to be strongly correlated with the predicted free energy of solvation of DME. The developed nonbonded force field parameters were found to be transferrable to poly(propylene oxide) (PPO), as confirmed by capturing, at least qualitatively, the miscibility of PPO in water as a function of the molecular weight.

  6. Conductivity of LiBF4/mixed ether electrolytes for secondary lithium cells (United States)

    Matsuda, Y.; Morita, M.; Yamashita, T.


    Electrolytic conductivity of LiBF4 has been studied in the mixed system of 1,3-dioxolane with 1,2-dimethoxyethane or with tetrahydrofuran. Relative permittivity (dielectric constant) of the solvents suggested the formation of associated ion pairs in the systems, but the conductivity measured was higher than that expected from the viewpoint of ionic association. Conductivity maxima were observed in the solutions containing about 1:1 (by volume) mixed solvents. Viscosities of the solvent and the solution were also measured, and their contribution to the conductivity change with the solvent composition was discussed. Solute concentration dependence of the molar conductivity was specific for the ether solutions. Apparent activation energy for conduction, which was determined by the temperature dependence of the conductivity, varied with LiBF4 concentration. Structural specificity of the mixed ether solutions was discussed with these parameters and H-1 NMR spectra of the solutions.

  7. The effect of solvent compatibilization in nanocomposite materials

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    Bates, S.E.; Black, E.P.; Ulibarri, T.A.; Schaefer, D.W. [Sandia National Laboratories, Albuquerque, NM (United States)] Beaucage, G. [Univ. of Cincinnati, OH (United States)] [and others


    The ability to control the phase separation in sol-gel derived silica/siloxane nanocomposites allows the generation of materials with tailored mechanical properties. One factor that seriously affects the phase separation in a system is the miscibility, both initial and over the lifetime of the reaction. We have examined the effect of changing the phase compatibility by adding a variety of organic solvents to the reaction mixture (e.g., tetrahydrofuran, toluene, xylene and 1,2-dimethoxyethane). In addition, we have varied the amount of solvent added to the system. The microstructure of the phase separation has been analyzed using Scanning Electron Microscopy (SEM) and Small Angle Neutron, X-ray and Light Scattering (SANS, SAXS and SALS). We have investigated the effect the phase separation changes have on the mechanical properties of the resulting materials by looking at the tensile strength, durometer and elongation properties. Findings from this investigation will be reviewed.

  8. Double stabilization of nanocrystalline silicon: a bonus from solvent

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    Kolyagin, Y. G.; Zakharov, V. N.; Yatsenko, A. V.; Paseshnichenko, K. A.; Savilov, S. V.; Aslanov, L. A., E-mail: [Lomonosov Moscow State University (Russian Federation)


    Double stabilization of the silicon nanocrystals was observed for the first time by {sup 29}Si and {sup 13}C MAS NMR spectroscopy. The role of solvent, 1,2-dimethoxyethane (glyme), in formation and stabilization of silicon nanocrystals as well as mechanism of modification of the surface of silicon nanocrystals by nitrogen-heterocyclic carbene (NHC) was studied in this research. It was shown that silicon nanocrystals were stabilized by the products of cleavage of the C–O bonds in ethers and similar compounds. The fact of stabilization of silicon nanoparticles with NHC ligands in glyme was experimentally detected. It was demonstrated that MAS NMR spectroscopy is rather informative for study of the surface of silicon nanoparticles but it needs very pure samples.

  9. A transferable force field to predict phase equilibria and surface tension of ethers and glycol ethers. (United States)

    Ferrando, Nicolas; Lachet, Véronique; Pérez-Pellitero, Javier; Mackie, Allan D; Malfreyt, Patrice; Boutin, Anne


    We propose a new transferable force field to simulate phase equilibrium and interfacial properties of systems involving ethers and glycol ethers. On the basis of the anisotropic united-atom force field, only one new group is introduced: the ether oxygen atom. The optimized Lennard-Jones (LJ) parameters of this atom are identical whatever the molecule simulated (linear ether, branched ether, cyclic ether, aromatic ether, diether, or glycol ether). Accurate predictions are achieved for pure compound saturated properties, critical properties, and surface tensions of the liquid-vapor interface, as well as for pressure-composition binary mixture diagrams. Multifunctional molecules (1,2-dimethoxyethane, 2-methoxyethanol, diethylene glycol) have also been studied using a recently proposed methodology for the calculation of the intramolecular electrostatic energy avoiding the use of additional empirical parameters. This new force field appears transferable for a wide variety of molecules and properties. It is furthermore worth noticing that binary mixtures have been simulated without introducing empirical binary parameters, highlighting also the transferability to mixtures. Hence, this new force field gives future opportunities to simulate complex systems of industrial interest involving molecules with ether functions.

  10. Enhanced Cycling Stability of Rechargeable Li-O2 Batteries Using High Concentration Electrolytes

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    Liu, Bin; Xu, Wu; Yan, Pengfei; Sun, Xiuliang; Bowden, Mark E.; Read, Jeffrey; Qian, Jiangfeng; Mei, Donghai; Wang, Chong M.; Zhang, Jiguang


    The electrolyte stability against reactive reduced-oxygen species is crucial for the development of rechargeable Li-O2 batteries. In this work, we systematically investigated the effect of lithium salt concentration in 1,2-dimethoxyethane (DME)-based electrolytes on the cycling stability of Li-O2 batteries. Cells with high concentration electrolyte illustrate largely enhanced cycling stability under both the full discharge/charge (2.0-4.5 V vs. Li/Li+) and the capacity limited (at 1,000 mAh g-1) conditions. These cells also exhibit much less reaction-residual on the charged air electrode surface, and much less corrosion to the Li metal anode. The density functional theory calculations are conducted on the molecular orbital energies of the electrolyte components and the Gibbs activation barriers for superoxide radical anion to attack DME solvent and Li+-(DME)n solvates. In a highly concentrated electrolyte, all DME molecules have been coordinated with salt and the C-H bond scission of a DME molecule becomes more difficult. Therefore, the decomposition of highly concentrated electrolyte in a Li-O2 battery can be mitigated and both air-cathodes and Li-metal anodes exhibits much better reversibility. As a results, the cyclability of Li-O2 can be largely improved.

  11. Organic derivatives of Mg(BH4)2 as precursors towards MgB2 and novel inorganic mixed-cation borohydrides. (United States)

    Wegner, W; Jaroń, T; Dobrowolski, M A; Dobrzycki, Ł; Cyrański, M K; Grochala, W


    A series of organic derivatives of magnesium borohydride, including Mg(BH4)2·1.5DME (DME = 1,2-dimethoxyethane) and Mg(BH4)2·3THF (THF = tetrahydrofuran) solvates and three mixed-cation borohydrides, [Cat]2[Mg(BH4)4], [Cat] = [Me4N], [nBu4N], [Ph4P], have been characterized. The phosphonium derivative has been tested as a precursor for synthesis of inorganic mixed-metal borohydrides of magnesium, Mx[Mg(BH4)2+x], M = Li-Cs, via a metathetic method. The synthetic procedure has yielded two new derivatives of heavier alkali metals M3Mg(BH4)5 (M = Rb, Cs) mixed with amorphous Mg(BH4)2. Thermal decomposition has been studied for both the organic and inorganic magnesium borohydride derivatives. Amorphous MgB2 has been detected among the products of the thermal decomposition of the solvates studied, together with organic and inorganic impurities.

  12. Dielectric Properties of Poly(ethylene oxide) from Molecular Dynamics Simulations (United States)

    Smith, Grant D.


    The order, conformations and dynamics of poly(oxyethylene) (POE) melts have been investigated through molecular dynamics simulations. The potential energy functions were determined from detailed ab initio electronic structure calculations of the conformational energies of the model molecules 1,2-dimethoxyethane (DME) and diethylether. The x-ray structure factor for POE from simulation will be compared to experiment. In terms of conformation, simulations reveal that chains are extended in the melt relative to isolated chains due to the presence of strong intermolecular O...H interactions, which occur at the expense of intramolecular O...H interactions. Conformational dynamics about the C-C bond were found to be significantly faster than in polymethylene, while conformational dynamics about the C-O bond even faster than the C-C dynamics. The faster local dynamics in POE relative to polymethylene is consistent with C-13 NMR spin-lattice relaxation experiments. Conformational transitions showed significant second-neighbor correlation, as was found for polymethylene. This correlation of transitions with C-C neighbors was found to be reduced relative to C-O neighbors. Dielectric relaxation from simulation will also be compared with experiment.

  13. Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes. (United States)

    Bortoluzzi, Marco; Ferretti, Eleonora; Marchetti, Fabio; Pampaloni, Guido; Pinzino, Calogero; Zacchini, Stefano


    The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.

  14. Electrolytes for Low-Temperature Operation of Li-CFx Cells (United States)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah


    A report describes a study of electrolyte compositions selected as candidates for improving the low-temperature performances of primary electrochemical cells that contain lithium anodes and fluorinated carbonaceous (CFx) cathodes. This study complements the developments reported in Additive for Low-Temperature Operation of Li-(CF)n Cells (NPO- 43579) and Li/CFx Cells Optimized for Low-Temperature Operation (NPO- 43585), which appear elsewhere in this issue of NASA Tech Briefs. Similar to lithium-based electrolytes described in several previous NASA Tech Briefs articles, each of these electrolytes consisted of a lithium salt dissolved in a nonaqueous solvent mixture. Each such mixture consisted of two or more of the following ingredients: propylene carbonate (PC); 1,2-dimethoxyethane (DME); trifluoropropylene carbonate; bis(2,2,2-trifluoroethyl) ether; diethyl carbonate; dimethyl carbonate; and ethyl methyl carbonate. The report describes the physical and chemical principles underlying the selection of the compositions (which were not optimized) and presents results of preliminary tests made to determine effects of the compositions upon the low-temperature capabilities of Li-CFx cells, relative to a baseline composition of LiBF4 at a concentration of 1.0 M in a solvent comprising equal volume parts of PC and DME.

  15. Substitution of fluorine in M[C6F5BF3] with organolithium compounds: distinctions between O- and N-nucleophiles

    Directory of Open Access Journals (Sweden)

    Anton Yu. Shabalin


    Full Text Available Borates M[C6F5BF3] (M = K, Li, Bu4N react with organolithium compounds, RLi (R = Me, Bu, Ph, in 1,2-dimethoxyethane or diglyme to give M[4-RC6F4BF3] and M[2-RC6F4BF3]. When R is Me or Bu, the nucleophilic substitution of the fluorine atom at the para position to boron is the predominant route. When R = Ph, the ratio M[4-RC6F4BF3]/M[2-RC6F4BF3] is ca. 1:1. Substitution of the fluorine atom at the ortho position to boron is solely caused by the coordination of RLi via the lithium atom with the fluorine atoms of the BF3 group. This differs from the previously reported substitution in K[C6F5BF3] by O- and N-nucleophiles that did not produce K[2-NuC6F4BF3].

  16. Activation of Ene-Diamido Samarium Methoxide with Hydrosilane for Selectively Catalytic Hydrosilylation of Alkenes and Polymerization of Styrene: an Experimental and Theoretical Mechanistic Study. (United States)

    Li, Jianfeng; Zhao, Chaoyue; Liu, Jinxi; Huang, Hanmin; Wang, Fengxin; Xu, Xiufang; Cui, Chunming


    Samarium methoxide incorporating the ene-diamido ligand L(DME)Sm(μ-OMe)2Sm(DME)L (1; L = [DipNC(Me)C(Me)NDip](2-), Dip = 2,6-iPr2C6H3, and DME = 1,2-dimethoxyethane) has been prepared and structurally characterized. Complex 1 catalyzed the syndiospecific polymerization of styrene upon activation with phenylsilane and regioselective hydrosilylation of styrenes and nonactivated terminal alkenes. Unprecedented regioselectivity (>99.0%) for both types of alkenes has been achieved with the formation of Markovnikov and anti-Markovnikov products in high yields, respectively, whereas the polymerization of styrene resulted in the formation of syndiotactic silyl-capped oligostyrenes. The kinetic experiments and density functional theory calculations strongly support a samarium hydride intermediate generated by σ-bond metathesis of the Sm-OMe bond in 1 with PhSiH3. In addition, the observed regioselectvity for hydrosilylation and polymerization is consistent with the calculated energy profiles, which suggests that the bulky ene-diamido ligand and samarium hydride intermediate have important roles for regio- and stereoselectivity.

  17. Syntheses and Properties of Homoleptic Carbonyl and Trifluorophosphane Niobates: [Nb(CO)(6)](-), [Nb(PF(3))(6)](-) and [Nb(CO)(5)](3)(-) (,)(1). (United States)

    Barybin, Mikhail V.; Ellis, John E.; Pomije, Marie K.; Tinkham, Mary L.; Warnock, Garry F.


    Reductive carbonylations of NbCl(4)(THF)(2), THF = tetrahydrofuran, mediated by sodium naphthalene in 1,2-dimethoxyethane, DME, or sodium anthracene in THF, provide [Nb(CO)(6)](-) as the tetraethylammonium salt in 60% or 70% isolated yields, respectively, the highest known for atmospheric pressure syntheses of this metal carbonyl. Corresponding reductions involving PF(3) give about 40% yields of [Et(4)N][Nb(PF(3))(6)], which in the past was only accessible by a photochemical route. Electrochemical data for [Nb(CO)(6)](-) and [Nb(PF(3))(6)](-) are compared and show that the PF(3) complex is almost 1 V more difficult to oxidize than the CO analogue. Protonation of [Nb(PF(3))(6)](-) by concentrated sulfuric acid yields a volatile, thermally unstable species, which has been shown by (1)H NMR and mass spectral studies to be the new niobium hydride, Nb(PF(3))(6)H. Previously unpublished (93)Nb and (13)C NMR studies corroborate prior claims that the sodium metal reduction of [Nb(CO)(6)](-) in liquid ammonia affords [Nb(CO)(5)](3)(-), the only known Nb(III-) species. The first details of this synthesis and those of [Nb(CO)(5)H](2)(-), [Nb(CO)(5)SnPh(3)](2)(-), [Nb(CO)(5)NH(3)](-), and [Nb(CO)(5)(CNtBu)](-) are presented.

  18. Comparison of Oxygen Gauche Effects in Poly(Oxyethylene) and Poly(ethylene terephtylene) Based on Quantum Chemistry Calculations (United States)

    Jaffe, Richard; Han, Jie; Yoon, Do; Langhoff, Stephen R. (Technical Monitor)


    The so-called oxygen gauche effect in poly(oxyethylene) (POE) and its model molecules such as 1,2-dimethoxyethane (DME) and diglyme (CH3OC2H4OC2H4OCH3) is manifested in the preference for gauche C-C bond conformations over trans. This has also been observed for poly(ethylene terephthalate) (PET). Our previous quantum chemistry calculations demonstrated that the large C-C gauche population in DME is due, in part, to a low-lying tg +/- g+ conformer that exhibits a substantial 1,5 CH ... O attraction. New calculations will be described that demonstrate the accuracy of the original quantum chemistry calculations. In addition, an extension of this work to model molecules for PET will be presented. It is seen that the C-C gauche preference is much stronger in 1,2 diacetoxyethane than in DME. In addition, there exist low-lying tg +/- g+/- and g+/-g+/-g+/- conformers that exhibit 1,5 CH ... O attractions involving the carbonyl oxygens. It is expected that the -O-C-C-O- torsional properties will be quite different in these two polymers. The quantum chemistry results are used to parameterize rotational isomeric states models (RIS) and force fields for molecular dynamics simulations of these polymers.

  19. Li/CFx Cells Optimized for Low-Temperature Operation (United States)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah


    Some developments reported in prior NASA Tech Briefs articles on primary electrochemical power cells containing lithium anodes and fluorinated carbonaceous (CFx) cathodes have been combined to yield a product line of cells optimized for relatively-high-current operation at low temperatures at which commercial lithium-based cells become useless. These developments have involved modifications of the chemistry of commercial Li/CFx cells and batteries, which are not suitable for high-current and low-temperature applications because they are current-limited and their maximum discharge rates decrease with decreasing temperature. One of two developments that constitute the present combination is, itself, a combination of developments: (1) the use of sub-fluorinated carbonaceous (CFx wherein xLiBF4 dissolved at a concentration of 0.5 M in a mixture of four volume parts of 1,2 dimethoxyethane with one volume part of propylene carbonate. The proportion, x, of fluorine in the cathode in such a cell lies between 0.5 and 0.9. The best of such cells fabricated to date have exhibited discharge capacities as large as 0.6 A h per gram at a temperature of 50 C when discharged at a rate of C/5 (where C is the magnitude of the current, integrated for one hour, that would amount to the nominal charge capacity of a cell).

  20. On the possibility to grow zinc oxide-based transparent conducting oxide films by hot-wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abrutis, Adulfas, E-mail:; Silimavicus, Laimis; Kubilius, Virgaudas; Murauskas, Tomas; Saltyte, Zita; Kuprenaite, Sabina; Plausinaitiene, Valentina [Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania)


    Hot-wire chemical vapor deposition (HW-CVD) was applied to grow zinc oxide (ZnO)-based transparent conducting oxide (TCO) films. Indium (In)-doped ZnO films were deposited using a cold wall pulsed liquid injection CVD system with three nichrome wires installed at a distance of 2 cm from the substrate holder. The wires were heated by an AC current in the range of 0–10 A. Zn and In 2,2,6,6-tetramethyl-3,5-heptanedionates dissolved in 1,2-dimethoxyethane were used as precursors. The hot wires had a marked effect on the growth rates of ZnO, In-doped ZnO, and In{sub 2}O{sub 3} films; at a current of 6–10 A, growth rates were increased by a factor of ≈10–20 compared with those of traditional CVD at the same substrate temperature (400 °C). In-doped ZnO films with thickness of ≈150 nm deposited on sapphire-R grown at a wire current of 9 A exhibited a resistivity of ≈2 × 10{sup −3} Ωcm and transparency of >90% in the visible spectral range. These initial results reveal the potential of HW-CVD for the growth of TCOs.

  1. Dinuclear Pentacarbonyl Tungsten Complex Bridged by Bis(3,5-dimethylpyrazol- 1- yl ) methane

    Institute of Scientific and Technical Information of China (English)

    赵雪梅; 唐良富; 杨攀; 王积涛


    A new bis (pyrazol-l-yl ) methane ligand, [Ph2(HO)CCH(3,5-Me2Pz)2, Pz=pyrazole] (1), with a bulky substituent on the methine carbon atom has been successfully synthesized by the reaction of bis(3,5- dimethylpyrazol-l-yl ) methyllithinm with benzophenone. Treatment of this ligand with W (CO)6 under UV-irradiation in THF at room temperature afforded a novel dinuclear complex CH2[3,5-Me2PzW(CO)5]2 (2) with loss of the Ph2CO fragment, which was characterized by IR, 1H NMR spectra and elemental analyses as well as the X-ray single crystal diffraction analysis. This compound crystallizes in the orthorhombic space group Pbcn, with a = 1.7690(3) nm, b=1.4460(3) nm, c = 1.2994(2) nm, Z = 4, V = 3.3239(10)nm3, De= 1.775g·cm-3, μ=6.967 mm-l, F (000) = 1672,Rl =0.0414 and wR 2 = 0.0988. Bis (3,5-dimethylpyrazol-l-yl) methane acts as a bridging bidentate ligand in this complex,which links two W (CO)5 fragments. In addition, heating this complex under reflux in 1,2-dimethoxyethane (DME) gives the known chelated mononuclear complex CH2(3,5-Me2Pz)2-W(CO)4 (3).

  2. Solution phase synthesis of aluminum-doped silicon nanoparticles via room-temperature, solvent based chemical reduction of silicon tetrachloride (United States)

    Mowbray, Andrew James

    We present a method of wet chemical synthesis of aluminum-doped silicon nanoparticles (Al-doped Si NPs), encompassing the solution-phase co-reduction of silicon tetrachloride (SiCl4) and aluminum chloride (AlCl 3) by sodium naphthalide (Na[NAP]) in 1,2-dimethoxyethane (DME). The development of this method was inspired by the work of Baldwin et al. at the University of California, Davis, and was adapted for our research through some noteworthy procedural modifications. Centrifugation and solvent-based extraction techniques were used throughout various stages of the synthesis procedure to achieve efficient and well-controlled separation of the Si NP product from the reaction media. In addition, the development of a non-aqueous, formamide-based wash solution facilitated simultaneous removal of the NaCl byproduct and Si NP surface passivation via attachment of 1-octanol to the particle surface. As synthesized, the Si NPs were typically 3-15 nm in diameter, and were mainly amorphous, as opposed to crystalline, as concluded from SAED and XRD diffraction pattern analysis. Aluminum doping at various concentrations was accomplished via the inclusion of aluminum chloride (AlCl3); which was in small quantities dissolved into the synthesis solution to be reduced alongside the SiCl4 precursor. The introduction of Al into the chemically-reduced Si NP precipitate was not found to adversely affect the formation of the Si NPs, but was found to influence aspects such as particle stability and dispersibility throughout various stages of the procedure. Analytical techniques including transmission electron microscopy (TEM), FTIR spectroscopy, and ICP-optical emission spectroscopy were used to comprehensively characterize the product NPs. These methods confirm both the presence of Al and surface-bound 1-octanol in the newly formed Si NPs.

  3. Tuning the Stability of Organic Active Materials for Nonaqueous Redox Flow Batteries via Reversible, Electrochemically Mediated Li + Coordination

    Energy Technology Data Exchange (ETDEWEB)

    Carino, Emily V.; Staszak-Jirkovsky, Jakub; Assary, Rajeev S.; Curtiss, Larry A.; Markovic, Nenad M.; Brushett, Fikile R.


    We describe an electrochemically mediated interaction between Li+ and a promising active material for nonaqueous redox flow batteries (RFBs), 1,2,3,4-tetrahydro-6,7-dimethoxy-1,1,4,4-tetramethylnaphthalene (TDT), and the impact of this structural interaction on material stability during voltammetric cycling. TDT could be an advantageous organic positive electrolyte material for nonaqueous RFBs due to its high oxidation potential, 4.21 V vs Li/Li+, and solubility of at least 1.0 M in select electrolytes. Although results from voltammetry suggest TDT displays Nernstian reversibility in many nonaqueous electrolyte solutions, bulk electrolysis reveals significant degradation in all electrolytes studied, the extent of which depends on the electrolyte solution composition. Results of subtractively normalized in situ Fourier transform infrared spectroscopy (SNIFTIRS) confirm that TDT undergoes reversible structural changes during cyclic voltammetry in propylene carbonate and 1,2-dimethoxyethane solutions containing Li+ electrolytes, but irreversible degradation occurs when tetrabutylammonium (TBA+) replaces Li+ as the electrolyte cation in these solutions. By combining the results from SNIFTIRS experiments with calculations from density functional theory, solution-phase active species structure and potential-dependent interactions can be determined. We find that Li+ coordinates to the Lewis basic methoxy groups of neutral TDT and, upon electrochemical oxidation, this complex dissociates into the radical cation TDT•+ and Li+. The improved cycling stability in the presence of Li+ relative to TBA+ suggests that the structural interaction reported herein may be advantageous to the design of energy storage materials based on organic molecules.

  4. Reversible switching of coordination mode of ansa bis(amidinate) ligand in ytterbium complexes driven by oxidation state of the metal atom. (United States)

    Tolpygin, Aleksei O; Cherkasov, Anton V; Fukin, Georgii K; Trifonov, Alexander A


    Reaction of bisamidine C6H4-1,2-{NC(t-Bu)NH(2,6-Me2C6H3)}2 (1) and [(Me3Si)2N]2Yb(THF)2 (THF = tetrahydrofuran) (toluene; room temperature) in a 1:1 molar ratio afforded a bis(amidinate) Yb(II) complex [C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]Yb(THF) (2) in 65% yield. Complex 2 features unusual κ(1)amide, η(6)-arene coordination of both amidinate fragments to the ytterbium ion, resulting in the formation of a bent bis(arene) structure. Oxidation of 2 by Ph3SnCl (1:1 molar ratio) or (PhCH2S)2 (1:0.5) leads to the Yb(III) species [C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]YbCl(1,2-dimethoxyethane) (3) and {[C6H4-1,2-{NC(t-Bu)N(2,6-Me2C6H3)}2]Yb(μ-SCH2Ph)}2 (4), performing "classic" κ(2)N,N'-chelating coordination mode of ansa bis(amidinate) ligand. By the reduction of 3 with equimolar amount of sodium naphthalide [C10H8(•-)][Na(+)] in THF, complex 2 can be recovered and restored to a bent bis(arene) structure. Complex 3 was also synthesized by the salt metathesis reaction of equimolar amounts of YbCl3 and the dilithium derivative of 1 in THF.

  5. Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mouat, Aidan R.; Lohr, Tracy L.; Wegener, Evan C.; Miller, Jeffrey T.; Delferro, Massimiliano; Stair, Peter C.; Marks, Tobin J.


    A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface- area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with ΔH = 10.5(8) kcal mol-1 and ΔS = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and lowcost catalyst with significant potential for transesterification processes.

  6. Synthesis and structures of calcium and strontium 2,4-di-tert-butylphenolates and their reactivity towards the amine co-initiated ring-opening polymerisation of rac-lactide. (United States)

    Clark, Lawrence; Deacon, Glen B; Forsyth, Craig M; Junk, Peter C; Mountford, Philip; Townley, Josh P; Wang, Jun


    Calcium and strontium metals react with Hg(C6F5)2 and 2,4-di-tert-butylphenol (H-DBP) in tetrahydrofuran (THF) and 1,2-dimethoxyethane (DME) to give [Ca(DBP)2(THF)4] (1), [Ca2(DBP)4(DME)4(μ-DME)] (2), [Sr3(μ-DBP)6(THF)6] (3), and [Sr2(DBP)(μ-DBP)3(DME)3] (4). Compound 1 is a six coordinate trans-octahedral monomer, whereas in binuclear 2 two seven-coordinate Ca centres are bridged by a DME ligand. In 3 a central Sr is connected by three bridging DBP groups to each of two terminal Sr(THF)3 moieties, all metal atoms being six coordinate. Compound 4 has one six- and one seven-coordinate Sr, bridged by three DBP ligands, the former Sr also having a terminal DBP and a bidentate DME ligand and the latter two DME ligands. Complexes 2 and 4 act as ring-opening polymerisation (ROP) catalysts for the benzyl alcohol or benzylamine co-initiated ROP rac-lactide forming atactic alcohol- or amine-terminated polylactide H-[PLA]-XBn (X = O or NH) with reasonable control of molecular weight via an activated monomer propagation mechanism. Kinetic studies for BnNH2 found the unusual rate expression -d[LA]/dt = k(p(Ae))[2 or 4]0[rac-LA](2)[BnNH2]0(2.5) (k(p(Ca)) ≈ 1.7 ×k(p(Sr))). Preliminary studies suggest that [Y(DBP)3(THF)2] also catalyses amine or alcohol co-initiated ROP by an activated monomer mechanism without loss of a phenoxide ligand.

  7. Diphenylamido Precursors to Bisalkoxide Molybdenum Olefin Metathesis Catalysts (United States)

    Sinha, Amritanshu; Müller, Peter; Hoveyda, Amir H.


    We have found that Mo(NAr)(CHR′)(NPh2)2 (R′ = t-Bu or CMe2Ph) and Mo(NAr′)(CHCMe2Ph)(NPh2)2 (Ar = 2,6-i-Pr2C6H3; Ar′ = 2,6-Me2C6H3) can be prepared through addition of two equivalents of LiNPh2 to Mo(NR″)(CHR′)(OTf)2(dme) species (R″ = Ar or Ar′ dme = 1,2-dimethoxyethane), although yields are low. A high yield route consists of addition of LiNPh2 to bishexafluro-t-butoxide species. An X-ray structure of Mo(NAr)(CHCMe2Ph)(NPh2)2 reveals that the two diphenylamido groups are oriented in a manner that allows an 18 electron count to be achieved. The diphenylamido complexes react readily with t-BuOH and (CF3)2MeCOH, but not readily with the sterically demanding biphenol H2[Biphen] (Biphen2- = 3,3′-Di-t-butyl-5,5′,6,6′-tetramethyl-1,1′-Biphenyl-2,2′-diolate). The diphenylamido complexes do react with various 3,3′-disubstituted binaphthols to yield binaphtholate catalysts that can be prepared in situ and employed for a simple asymmetric ring-closing metathesis reaction. In several cases conversions and enantioselectivities were comparable to reactions in which isolated catalysts were employed. PMID:19030118

  8. Phthalocyanine as a chemically inert, redox-active ligand: structural and electronic properties of a Nb(IV)-oxo complex incorporating a highly reduced phthalocyanine(4-) anion. (United States)

    Wong, Edwin W Y; Walsby, Charles J; Storr, Tim; Leznoff, Daniel B


    This report describes the reduction of a niobium(V) phthalocyanine complex and investigation of the electronic structure of the resulting products. The reduction of PcNbCl(3) (Pc = phthalocyanine dianion) with 5.5 equiv of potassium graphite in 1,2-dimethoxyethane (DME) resulted in the isolation of K(2)PcNbO.5DME (1a). Addition of 18-crown-6 to 1a gave [K(18-crown-6)](2)(mu-DME)PcNbO (1b). Both 1a and 1b were structurally characterized by single-crystal X-ray diffraction analysis. In both complexes, the niobium center adopts a square pyramidal geometry and is coordinated by four basal Pc nitrogen atoms and an apical oxo ligand. Notably, the Pc ligand in 1a is saddle-shaped, with significant bond length alternation, rather than flat with delocalized bonding. The production of ethylene during the reduction of PcNbCl(3), detected by gas chromatography/mass spectrometry (GC/MS), suggests that the oxo ligand likely results from double C-O bond activation of DME solvent. A combination of spectroscopic techniques and density functional theory (DFT) calculations were used to establish the electronic structure of 1a. The close correspondence of the electronic absorption spectrum of 1a to that of [PcZn](2-) with a di-reduced Pc(4-) ligand, indicates a similar electronic structure for the two complexes. Evaluation of the electronic transitions for 1a and [PcZn](2-) by time-dependent DFT calculations further suggests a similar electronic structure for both complexes, indicating that differences in symmetry between 1a and [PcZn](2-) do not significantly affect the nature of the electronic transitions. Electron paramagnetic resonance (EPR) spectroscopy of 1a in solution at room temperature gave a 10-line spectrum, while frozen-solution X- and Q-band EPR spectra are consistent with powder-pattern spectra defined by uniaxial g and (93)Nb hyperfine tensors: these imply the presence of a d(1) Nb(IV) metal center. EPR and electron nuclear double resonance spectroscopy suggests that

  9. Multinuclear NMR Study of the Solid Electrolyte Interface Formed in Lithium Metal Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Chuan; Xu, Suochang; Hu, Mary Y.; Cao, Ruiguo; Qian, Jiangfeng; Qin, Zhaohai; Liu, Jun; Mueller, Karl T.; Zhang, Ji-Guang; Hu, Jian Zhi


    The composition of the solid electrolyte interphase (SEI) layers associated with a high performance Cu|Li cell using lithium bis(fluorosulfonyi)imide (LiFSI) in 1,2-dimethoxyethane (DME) as electrolyte is determined by a multinuclear (6Li, 19F, 13C and 1H) solid-state MAS NMR study at high magnetic field (850 MHz). This cell can be cycled at high rates (4 mA•cm-2) for more than 1000 cycles with no increase in the cell impedance at high Columbic efficiency (average of 98.4%) in a highly concentrated LiFSI-DME electrolyte (4 M). LiFSI, LiF, Li2O2 (and/or CH3OLi), LiOH, Li2S and Li2O are observed in the SEI and validated by comparing with the spectra acquired on standard compounds and literature reports. To gain further insight into the role of the solute and its concentration dependence on the formation of SEIs while keeping the solvent of DME unchanged, the SEIs from different concentrations of LiFSI-DME and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-DME electrolyte are also investigated. It is found that LiF, a lithiated compound with superior mechanical strength and good Li+ ionic conductivity, is observed in the concentrated 4.0 M LiFSI-DME and the 3.0 M LiTFSI-DME systems but not in the diluted 1.0 M LiFSI-DME system. Li2O exists in both low and high concentration of LiFSI-DME while no Li2O is observed in the LiTFSI system. Furthermore, the dead metallic Li is reduced in the 4 M LiFSI-DME system compared with that in the 1 M LiFSI-DME system. Quantitative 6Li MAS results indicate that the SEI associated with the 4 M LiFSI-DEME is denser or thicker than that of the 1 M LiFSI-DME and the 3 M LiTFSI-DME systems. These findings are likely the reasons for explaining the high electrochemical performance associated with the high concentration LiFSI-DME system.

  10. Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties. (United States)

    Rausch, Janek; Lorenz, Volker; Hrib, Cristian G; Frettlöh, Vanessa; Adlung, Matthias; Wickleder, Claudia; Hilfert, Liane; Jones, Peter G; Edelmann, Frank T


    This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect.

  11. Synthesis and chemistry of organoimidovanadium(V) compounds and their role in the formation of vanadium nitrides (United States)

    Gipson, Rocky Dean

    A series of vanadium(V) compounds of the formula (eta5-C 5Me5)V(NR)Cl2 (R = 1-adamantyl, tert-butyl, para-tolyl) have been prepared by the reaction of (eta5 -C5Me5)V(O)Cl2 with RNCO or by oxidation of [(eta5-C5Me5)VCl2] 3 with azide. The para-tolylimido compound undergoes chloride metathesis with monoanionic reagents NaOtBu, LiNEt 2, and Mg(CH2SiMe3)2 to produce mono- and disubstituted products. A discussion of ligand strength in this system using 51V NMR is presented. Ammonolysis of the dichloro compounds produces the symmetrically-bridged [(eta5-C5Me5)V(mu-N)Cl]2, in yields consistent with the basicity of the organoimido ligand. A comparison of this reactivity with that of (eta5-C5Me 5)V(NSiMe3)Cl2 is presented. An X-ray structural study of (eta5-C5Me5)V(NtBu)Cl 2 exhibits a 173° V-N-C imido linkage and V-N triple bond. Synthesis of (eta5-tBuC5H 4)V(NR)Cl2 compounds was performed utilizing (t-Bu)C 5H4SiMe3 as the cyclopentadiene reagent with V(NR)Cl 3. In contrast to the metathesis of V(NR)Cl3 compounds with Li(tBu)C5H4, reduction of the vanadium(V) is not observed. An X-ray crystal structure of (eta5- tBuC5H4)V(N-ptol)Cl2 reveals linear V-N-C bonding, and a short N-C bond of 139 pm. This is explained by delocalized bonding, which incorporates the imido carbon atoms as well as nitrogen and vanadium. Details of the structure and valence-bond descriptions are of this compound are presented. Organoimidotrichlorovanadium(V) compounds bind ligands L2 (L2 = 1,2-dimethoxyethane; N,N,N,N-tetramethylethylenediamine) to produce adducts V(NR)Cl3L2. The V(NR)Cl3L 2 compounds thermally react to form terminal nitrides V(N)Cl2L 2 via an unprecedented cleavage of the N-C bond of the organoimido ligand, with reactivity following the order t-butyl > 1-adamantyl > p-tolyl. The downfield 51V NMR shifts of the adducts relative to starting materials is discussed using crystal-field models. X-ray crystal structures of V(NAd)Cl3(DME) and V(N ptol)Cl3(TMEDA) are presented, and details

  12. Halide, amide, cationic, manganese carbonylate, and oxide derivatives of triamidosilylamine uranium complexes. (United States)

    Gardner, Benedict M; Lewis, William; Blake, Alexander J; Liddle, Stephen T


    Treatment of the complex [U(Tren(TMS))(Cl)(THF)] [1, Tren(TMS) = N(CH(2)CH(2)NSiMe(3))(3)] with Me(3)SiI at room temperature afforded known crystalline [U(Tren(TMS))(I)(THF)] (2), which is reported as a new polymorph. Sublimation of 2 at 160 °C and 10(-6) mmHg afforded the solvent-free dimer complex [{U(Tren(TMS))(μ-I)}(2)] (3), which crystallizes in two polymorphic forms. During routine preparations of 1, an additional complex identified as [U(Cl)(5)(THF)][Li(THF)(4)] (4) was isolated in very low yield due to the presence of a slight excess of [U(Cl)(4)(THF)(3)] in one batch. Reaction of 1 with one equivalent of lithium dicyclohexylamide or bis(trimethylsilyl)amide gave the corresponding amide complexes [U(Tren(TMS))(NR(2))] (5, R = cyclohexyl; 6, R = trimethylsilyl), which both afforded the cationic, separated ion pair complex [U(Tren(TMS))(THF)(2)][BPh(4)] (7) following treatment of the respective amides with Et(3)NH·BPh(4). The analogous reaction of 5 with Et(3)NH·BAr(f)(4) [Ar(f) = C(6)H(3)-3,5-(CF(3))(2)] afforded, following addition of 1 to give a crystallizable compound, the cationic, separated ion pair complex [{U(Tren(TMS))(THF)}(2)(μ-Cl)][BAr(f)(4)] (8). Reaction of 7 with K[Mn(CO)(5)] or 5 or 6 with [HMn(CO)(5)] in THF afforded [U(Tren(TMS))(THF)(μ-OC)Mn(CO)(4)] (9); when these reactions were repeated in the presence of 1,2-dimethoxyethane (DME), the separated ion pair [U(Tren(TMS))(DME)][Mn(CO)(5)] (10) was isolated instead. Reaction of 5 with [HMn(CO)(5)] in toluene afforded [{U(Tren(TMS))(μ-OC)(2)Mn(CO)(3)}(2)] (11). Similarly, reaction of the cyclometalated complex [U{N(CH(2)CH(2)NSiMe(2)Bu(t))(2)(CH(2)CH(2)NSiMeBu(t)CH(2))}] with [HMn(CO)(5)] gave [{U(Tren(DMSB))(μ-OC)(2)Mn(CO)(3)}(2)] [12, Tren(DMSB) = N(CH(2)CH(2)NSiMe(2)Bu(t))(3)]. Attempts to prepare the manganocene derivative [U(Tren(TMS))MnCp(2)] from 7 and K[MnCp(2)] were unsuccessful and resulted in formation of [{U(Tren(TMS))}(2)(μ-O)] (13) and [MnCp(2)]. Complexes 3-13 have been

  13. Molybdenum (VI Imido Complexes Derived from Chelating Phenols: Synthesis, Characterization and ɛ-Caprolactone ROP Capability

    Directory of Open Access Journals (Sweden)

    Yahya Al-Khafaji


    Full Text Available Reaction of the bulky bi-phenols 2,2′-RCH[4,6-(t-Bu2C6H2OH]2 (R = Me L1MeH2, Ph L1PhH2 with the bis(imido molybdenum(VI tert-butoxides [Mo(NR1(NR2(Ot-Bu2] (R1 = R2 = 2,6-C6H3-i-Pr2; R1 = t-Bu, R2 = C6F5 afforded, following the successive removal of tert-butanol, the complexes [Mo(NC6H3i-Pr2-2,62L1Me] (1, [Mo(NC6H3i-Pr2-2,62L1Ph] (2 and [Mo(Nt-Bu(μ-NC6F5(L1Me]2 (3. Similar use of the tri-phenol 2,6-bis(3,5-di-tert -butyl-2-hydroxybenzyl-4-methylphenol (L2H3 with [Mo(NC6H3i-Pr2-2,62(Ot-Bu2] afforded the oxo-bridged product [Mo(NC6H3i-Pr2-2,6(NCMe(μ-OL2H]2 (4, whilst use of the tetra-phenols α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl-p- or -m-xylene L3pH4/L3mH4 led to {[Mo(NC6H3i-Pr2-2,62]2(μ-L3p} (5 or {[Mo(NC6H3i-Pr2-2,62]2(μ-L3m} (6, respectively. Similar use of [Mo(NC6F52(Ot-Bu2] with L3pH4 afforded, after work-up, the complex {[Mo(NC6F5(Ot-Bu2]2(μ-L3p}·6MeCN (7·6MeCN. Molecular structures of 1, 2·CH2Cl2, 3, 4·6MeCN, 6·2C6H14, and 7·6MeCN are reported and these complexes have been screened for their ability to ring open polymerize (ROP ε-caprolactone; for comparative studies the precursor complex [Mo(NC6H3i-Pr2-2,62Cl2(DME] (DME = 1,2-dimethoxyethane has also been screened. Results revealed that good activity is only achievable at temperatures of ≥100 °C over periods of 1 h or more. Polymer polydispersities were narrow, but observed molecular weights (Mn were much lower than calculated values.

  14. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald


    described in the previous literature for electrochemical reduction of spent fuels, have been attempted. A quantitative analytical method for measuring the concentration of sodium borohydride in alkaline aqueous solution has been developed as part of this work and is described herein. Finally, findings from stability tests for sodium borohydride in aqueous solutions of several different compositions are reported. For aminoborane, other research institutes have developed regeneration schemes involving tributyltin hydride. In this report, electrochemical reduction experiments attempting to regenerate tributyltin hydride from tributyltin chloride (a representative by-product of the regeneration scheme) are described. These experiments were performed in the non-aqueous solvents acetonitrile and 1,2-dimethoxyethane. A non-aqueous reference electrode for electrolysis experiments in acetonitrile was developed and is described. One class of boron hydrides, called polyhedral boranes, became of interest to the DOE due to their ability to contain a sufficient amount of hydrogen to meet program goals and because of their physical and chemical safety attributes. Unfortunately, the research performed here has shown that polyhedral boranes do not react in such a way as to allow enough hydrogen to be released, nor do they appear to undergo hydrogenation from the spent fuel form back to the original hydride. After the polyhedral boranes were investigated, the project goals remained the same but the hydrogen storage material was switched by the DOE to ammonia borane. Ammonia borane was found to undergo an irreversible hydrogen release process, so a direct hydrogenation was not able to occur. To achieve the hydrogenation of the spent ammonia borane fuel, an indirect hydrogenation reaction is possible by using compounds called organotin hydrides. In this process, the organotin hydrides will hydrogenate the spent ammonia borane fuel at the cost of their own oxidation, which forms organotin

  15. Novel inorganic heterocycles from dimetalated carboranylamidinates. (United States)

    Harmgarth, Nicole; Gräsing, Daniel; Dröse, Peter; Hrib, Cristian G; Jones, Peter G; Lorenz, Volker; Hilfert, Liane; Busse, Sabine; Edelmann, Frank T


    Mono- and dianionic carboranylamidinates are readily available in one-pot reactions directly from o-carborane (1). In situ-monolithiation of 1 followed by treatment with N,N'-diisopropylcarbodiimide, (i)PrN=C=N(i)Pr, or N,N'-dicyclohexylcarbodiimide, CyN=C=NCy, provided the lithium carboranylamidinates (o-C2B10H10C(NH(i)Pr)(=N(i)Pr)-κ(2)C,N)Li(DME) (2a) and (o-C2B10H10C(NH(i)Cy)(=N(i)Cy)-κ(2)C,N)Li(THF)2 (2b). Controlled hydrolysis of 2a,b afforded the free carboranylamidines o-C2B10H11C(NH(i)R)(=N(i)R) (3a: R = (i)Pr, 3b: R = Cy). The first dimetalated carboranylamidinates, o-C2B10H10C(N(i)Pr)(=N(i)Pr)Li2(DME)2 (4a) (DME = 1,2-dimethoxyethane) and o-C2B10H10C(N(i)Pr)(=N(i)Pr)Li2(THF)4 (4b), were prepared in high yield (83% yield) directly from 1 using a simple one-pot synthetic protocol. Treatment of 4b with 2 equiv. of Me3SiCl afforded the disilylated derivative o-C2B10H10-κ(2)C,N-[C(N(i)PrSiMe3)(=N(i)Pr)]SiMe3 (5). Dianionic 4b also served as an excellent precursor for novel inorganic heterocycles incorporating the closo-1,2-C2B10H10 cage, including the unsymmetrical distannene [o-C2B10H10C(N(i)Pr)(=N(i)Pr)-κ(2)C,N]Sn=Sn[((i)PrN)2C(n)Bu]2 (6) and the azaphosphole derivative [o-C2B10H10C(N(i)Pr)(=N(i)Pr)-κ(2)C,N]PPh (7). Surprisingly, it was found that the synthesis of new inorganic ring systems from dianionic carboranylamidinates can also be achieved by employing only 1 equiv. of n-butyllithium in the generation of the anionic carboranylamidinate intermediates. Using this straightforward one-pot synthetic protocol, the Group 14 metallacycles [o-C2B10H10C(NCy)(=NCy)-κ(2)C,N]SiR2 (R = Cl (8), Me (9), Ph (10)) and [o-C2B10H10C(NCy)([=NCy)-κ(2)C,N]GeCl2 (11) have become accessible. The same synthetic strategy could be successfully adapted to prepare the corresponding Group 4 metallocene derivatives Cp2Ti[o-C2B10H10C(NCy)(=NCy)-κ(2)C,N] (12) and Cp2Zr[o-C2B10H10C(NCy)(=NCy)-κ(2)C,N] (13). The molecular structures of 2b, 3b, 4b, 5, 6, 7, 10, 12, and 13 were

  16. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald


    described in the previous literature for electrochemical reduction of spent fuels, have been attempted. A quantitative analytical method for measuring the concentration of sodium borohydride in alkaline aqueous solution has been developed as part of this work and is described herein. Finally, findings from stability tests for sodium borohydride in aqueous solutions of several different compositions are reported. For aminoborane, other research institutes have developed regeneration schemes involving tributyltin hydride. In this report, electrochemical reduction experiments attempting to regenerate tributyltin hydride from tributyltin chloride (a representative by-product of the regeneration scheme) are described. These experiments were performed in the non-aqueous solvents acetonitrile and 1,2-dimethoxyethane. A non-aqueous reference electrode for electrolysis experiments in acetonitrile was developed and is described. One class of boron hydrides, called polyhedral boranes, became of interest to the DOE due to their ability to contain a sufficient amount of hydrogen to meet program goals and because of their physical and chemical safety attributes. Unfortunately, the research performed here has shown that polyhedral boranes do not react in such a way as to allow enough hydrogen to be released, nor do they appear to undergo hydrogenation from the spent fuel form back to the original hydride. After the polyhedral boranes were investigated, the project goals remained the same but the hydrogen storage material was switched by the DOE to ammonia borane. Ammonia borane was found to undergo an irreversible hydrogen release process, so a direct hydrogenation was not able to occur. To achieve the hydrogenation of the spent ammonia borane fuel, an indirect hydrogenation reaction is possible by using compounds called organotin hydrides. In this process, the organotin hydrides will hydrogenate the spent ammonia borane fuel at the cost of their own oxidation, which forms organotin