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Sample records for 1,2-dimethoxyethane

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

    Siou-Wei Ou

    2012-02-01

    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.

  2. Hydration modes of an amphiphilic molecule 2: NMR, FTIR and theoretical study of the interactions in the system water-1,2-dimethoxyethane

    Graphical abstract: Using NMR spectroscopy, PFG measurements, relaxations and NOESY, as well as FTIR spectroscopy and DFT calculations, 1,2-dimethoxyethane is shown to form a hydrate with five water molecules bound by cooperative hydrogen bonds. Highlights: → Binding of water to DME leads to tgt conformation at all water/DME ratios. → Water is bound to DME in a tight envelope containing at least five water molecules. → The hydration envelope is built up by cooperative O-H...O and O...H-C hydrogen bonds. - Abstract: Using 1H and 13C NMR spectra, PFG NMR self-diffusion measurements, 1H and 13C NMR relaxations and 1H NOESY NMR spectra, FTIR spectra and quantum-chemical DFT and MP2 calculations, the interaction of 1,2-dimethoxyethane (DME) with water (W) was re-examined. It was confirmed that, primarily, one W molecule forms two O...H hydrogen bonds with DME in tgt conformation. At medium and higher W contents, however, larger hydrates of DME are formed, predominantly with five W molecules. The compact structure of the hydrate is warranted by O...H hydrogen bonds, some of them perceptibly tighter than those in the primary hydrate, and by non-classical CH3...O hydrogen bonds.

  3. 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

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

    2016-02-01

    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.

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

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

    2016-03-01

    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.

  5. Catena-Poly[(2,5,8-trioxanonan-O2,O5)lithiummethylphosphanid] : eine Verbindung mit meso-Helix-Struktur (Metallderivate von Molekülverbindungen ; 8)

    Becker, Gerd; Eschbach, Bruno; Mundt, Otto; Seidler, Norbert

    1994-01-01

    Nach Untersuchungen von Fritz u. a. [10] wird in 1,2-Dimethoxyethan oder Bis(2-methoxyethyl)ether gelöstes Methylphosphan bei -60°C durch Lithium-n-butanid in n-Hexan metalliert. Beim Abkühlen der von Kohlenwasserstoffen weitgehend befreiten Ansätze auf wiederum -60°C kristallisiert (1,2-Dimethoxyethan-O,O)lithium- (1) bzw. (2,5,8-Trioxanonan-O2,O5) lithium-methylphosphanid (2) in farblosen Quadern aus. Nach einer Röntgenstrukturanalyse (monoklin, P21/n; a = 805,5(1); b = 1 820,6(2); c = 851,...

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

    2009-03-01

    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.

  7. On the mechanism of radical fragmentation of α-dioles and some of their derivatives

    Studied is the composition of radiolysis products of deluted deaerated aqueous solutions of 1.2-dimethoxyethane and some of 1.3-dioxolanes. The solutions were leached (pH 12-13) to prevent hydrolysis of both initial and final products. Cs137 was used as a source of γ-radiation. Absorbed dose rate is equal to 4x1015 eV/mlxs. On the basis of the results obtained and literary data on radical fragmentation of α-dioles a possibility of ROCHCH2OR' particle decomposition according to the coordinated mechanism is discussed

  8. Groups 5 and 6 Terminal Hydrazido(2−) Complexes: N_β Substituent Effects on Ligand-to-Metal Charge-Transfer Energies and Oxidation States

    Tonks, Ian A.; Durrell, Alec C.; Gray, Harry B.; Bercaw, John E.

    2012-01-01

    Brightly colored terminal hydrazido(2−) (dme)MCl_3(NNR_2) (dme = 1,2-dimethoxyethane; M = Nb, Ta; R = alkyl, aryl) or (MeCN)WCl_4(NNR_2) complexes have been synthesized and characterized. Perturbing the electronic environment of the β (NR_2) nitrogen affects the energy of the lowest-energy charge-transfer (CT) transition in these complexes. For group 5 complexes, increasing the energy of the N_β lone pair decreases the ligand-to-metal CT (LMCT) energy, except for electron-rich niobium dialkyl...

  9. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries.

    Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

    2016-01-01

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system. PMID:26878890

  10. Electrodeposition of Lithium from Lithium-Containing Solvate Ionic Liquids

    Vanhoutte, Gijs; Brooks, Neil R.; Schaltin, Stijn; Opperdoes, Bastiaan; Van Meervelt, Luc; Locquet, Jean-Pierre; Vereecken, Philippe M.; Fransaer, Jan; Binnemans, Koen

    2014-01-01

    Lithium-containing solvate ionic liquids [Li(L)n][X], with ligands L = 1,2-dimethoxyethane (G1, monoglyme) or 1-methoxy-2-(2-methoxyethyl)ether (G2, diglyme) (with n = 1, 2 or 3) and with anions X = bis(trifluoromethylsulfonyl)imide (Tf2N–), bromide (Br–) or iodide (I–), were synthesized and used as electrolytes for the electrodeposition of lithium metal. Very high lithium-ion concentrations could be obtained, since the lithium ion is part of the cationic structure of the solvate ionic liquid...

  11. Monitoring the Electrochemical Processes in the Lithium–Air Battery by Solid State NMR Spectroscopy

    Leskes, Michal; Moore, Amy J.; Goward, Gillian R.; Grey, Clare P.

    2013-01-01

    A multi-nuclear solid-state NMR approach is employed to investigate the lithium–air battery, to monitor the evolution of the electrochemical products formed during cycling, and to gain insight into processes affecting capacity fading. While lithium peroxide is identified by 17O solid state NMR (ssNMR) as the predominant product in the first discharge in 1,2-dimethoxyethane (DME) based electrolytes, it reacts with the carbon cathode surface to form carbonate during the charging process. 13C ss...

  12. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries

    Rongrong Miao; Jun Yang; Zhixin Xu; Jiulin Wang; Yanna Nuli; Limin Sun

    2016-01-01

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new ...

  13. A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries

    Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

    2016-02-01

    A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system.

  14. Binary sulfone/ether-based electrolytes for rechargeable lithium-sulfur batteries

    Lithium-sulfur (Li-S) batteries are a promising electrochemical system because they exhibit high theoretical capacity of 1672 mAh g−1. However, widespread use of these batteries has been hindered by the poor conductivity and high dissolution rate of the active materials as well as by the high reactivity of the lithium electrodes. In this study, we investigated the effects of the choice of electrolyte on the electrochemical performance of Li-S batteries. We studied a number of cyclic and acyclic sulfone-based electrolytes and found that the physical and electrochemical properties of the sulfone-based electrolytes, which could be varied by varying their composition, had an effect on the solubility of S8 in the electrolytes. It was observed that, in contrast to the electrolyte based on 1,2-dimethoxyethane, the one based on a mixture of tetramethylene sulfone/1,2-dimethoxyethane dissolved S8 (or Li2Sm) to a lower degree and resulted in stable electrochemical performance in Li-S batteries. Thus, the chemical reactivity of the solvent used for the electrolyte should be taken into consideration along with the physical properties of the active materials when designing Li-S batteries

  15. Synthesis and characterization of d2 imido complexes of molybdenum. Crystal structure of [MoCl2{N(mes)}(PhC≡CPh)-(PMe3)2]·0.5PhC≡CPh (mes = 2,4,6-trimethylphenyl)

    Montilla Ramos, Francisco Javier; Galindo del Pozo, Agustín; Carmona Guzmán, Ernesto; Gutiérrez Puebla, Enrique; Monge, Ángeles

    1998-01-01

    The compound [MoCl2{N(mes)}(PMe3)3] 1 (mes = 2,4,6-trimethylphenyl) has been prepared by the reaction of [MoCl3{N(mes)}(dme)] (dme = 1,2-dimethoxyethane) with 2 equivalents of PMe3 and subsequent sodium amalgam reduction, in the presence of 1 additional equivalent of PMe3. Metathesis reactions of 1 with KX gave [MoX2{N(mes)}(PMe3)3] (X = Br 2 or NCS 3), whereas the anionic bidentate PriOCS2– ligand produced the monophosphine compound [Mo{N(mes)}(S2COPri)2(PMe3)] 4. Substitution of two of the ...

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

    Kolyagin, Y. G.; Zakharov, V. N.; Yatsenko, A. V.; Paseshnichenko, K. A.; Savilov, S. V.; Aslanov, L. A., E-mail: aslanov.38@mail.ru [Lomonosov Moscow State University (Russian Federation)

    2016-01-15

    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.

  17. Catalytic activity trends of oxygen reduction reaction for nonaqueous Li-air batteries.

    Lu, Yi-Chun; Gasteiger, Hubert A; Shao-Horn, Yang

    2011-11-30

    We report the intrinsic oxygen reduction reaction (ORR) activity of polycrystalline palladium, platinum, ruthenium, gold, and glassy carbon surfaces in 0.1 M LiClO(4) 1,2-dimethoxyethane via rotating disk electrode measurements. The nonaqueous Li(+)-ORR activity of these surfaces primarily correlates to oxygen adsorption energy, forming a "volcano-type" trend. The activity trend found on the polycrystalline surfaces was in good agreement with the trend in the discharge voltage of Li-O(2) cells catalyzed by nanoparticle catalysts. Our findings provide insights into Li(+)-ORR mechanisms in nonaqueous media and design of efficient air electrodes for Li-air battery applications. PMID:22044022

  18. Henry’s constants and activity coefficients of some organic solutes in 1-butyl,3-methylimidazolium hydrogen sulfate and in 1-methyl,3-trimethylsilylmethylimidazolium chloride

    Highlights: ► New solubility data are reported for two ionic liquids. ► Density data are reported. ► Thermo-gravimetric analysis data are obtained. - Abstract: Using a customized capillary gas–liquid chromatography column, Henry’s constants and activity coefficients at infinite dilution are reported for benzene, toluene, ethyl acetate, 1,4-dioxane, 1,2-dimethoxyethane, acetonitrile, nitromethane, tetrahydrofuran, chloroform, methanol, ethanol, and 1-propanol in ionic liquids 1-butyl,3-methylimidazolium hydrogen sulfate [BMIM][HSO4] and 1-methyl,3-trimethylsilylmethylimidazolium [SiMIM][Cl] chloride from 313 to 413 K. These acidic ionic liquids may provide suitable media for acid-catalyzed chemical reactions.

  19. Direct Conversion of Mono- and Polysaccharides into 5-Hydroxymethylfurfural Using Ionic-Liquid Mixtures.

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

    2016-08-23

    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. PMID:27345462

  20. Unusually slow formation of ion-pair charge-transfer complex between 4,4'-bipyridinium and tetrakis(3,5-bis(trifluoromethyl)-phenyl)borate in organic solutions

    Nagamura, T.; Sakai, K. (Kyushu Univ., Fukuoka (Japan). Dept. of Molecular Science and Technology)

    1988-06-01

    4,4'-Bipyridinium salts with tetrakis(3,5-bis(trifluoromethyl)-phenyl)borate anion (abbreviated to TFPB{sup -}) showed a charge-transfer (CT) absorption above 350 nm with a discrete peak at about 475 nm in 1,2-dimethoxyethane and at 420 nm in methanol. The absorbance of a CT band increased very gradually to the equilibrium dependent on temperature. The CT fluorescence showed similar very slow growth. The observed time-dependences of absorbance and fluorescence were well explained by the temperature-dependent formation and dissociation of CT complexes. Very slow growth was attributed to the unusually small pre-exponential factor, which was most probably due to the extraordinary bulkiness of TFPB{sup -}. (orig.).

  1. Three-Dimensional Au Microlattices as Positive Electrodes for Li-O2 Batteries.

    Xu, Chen; Gallant, Betar M; Wunderlich, Phillip U; Lohmann, Timm; Greer, Julia R

    2015-06-23

    We demonstrate the feasibility of using a 3-dimensional gold microlattice with a periodic porous structure and independently tunable surface composition as a Li-O2 battery cathode. The structure provides a platform for studying electrochemical reactions in architected Li-O2 electrodes with large (300 μm) pore sizes. The lack of carbon and chemical binders in these Au microlattices enabled the investigation of chemical and morphological processes that occur on the surfaces of the microlattice during cycling. Li-O2 cells with Au microlattice cathodes were discharged in 0.5 M lithium-bis(trifluoromethane)sulfonamide (LiTFSI) in a 1,2-dimethoxyethane (DME) electrolyte, with lithium metal foil as the anode. SEM analysis of microlattice cathodes after first discharge revealed the presence of toroidal-shaped 500-700 nm particles covering the surface of the electrode, which disappeared upon subsequent charging. Raman and FTIR spectroscopy analysis determined these particulates to be Li2O2. The morphology of discharge products evolved with cycling into micrometer-sized clusters of arranged "platelets", with a higher amount of side reaction products such as Li2CO3 and LiOH. This work shows that properly designed 3-dimensional architected materials may provide a useful foundation for investigating fundamental surface electrochemistry while simultaneously enabling mechanical robustness and enhancing the surface area over a factor of 30 compared with a thin film with the same foot print. PMID:25950649

  2. High Rate and Stable Cycling of Lithium Metal Anode

    Qian, Jiangfeng; Henderson, Wesley A.; Xu, Wu; Bhattacharya, Priyanka; Engelhard, Mark H.; Borodin, Oleg; Zhang, Jiguang

    2015-02-20

    Lithium (Li) metal is an ideal anode material for rechargeable batteries. However, dendritic Li growth and limited Coulombic efficiency (CE) during repeated Li deposition/stripping processes have prevented the application of this anode in rechargeable Li metal batteries, especially for use at high current densities. Herein, we report that the use of highly concentrated electrolytes composed of ether solvents and the lithium bis(fluorosulfonyl)imide (LiFSI) salt enables the high rate cycling of a Li metal anode at high CE (up to 99.1 %) without dendrite growth. With 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte, a Li|Li cell can be cycled at high rates (10 mA cm-2) for more than 6000 cycles with no increase in the cell impedance, and a Cu|Li cell can be cycled at 4 mA cm-2 for more than 1000 cycles with an average CE of 98.4%. These excellent high rate performances can be attributed to the increased solvent coordination and increased availability of Li+ concentration in the electrolyte. Further development of this electrolyte may lead to practical applications for Li metal anode in rechargeable batteries. The fundamental mechanisms behind the high rate ion exchange and stability of the electrolytes also shine light on the stability of other electrochemical systems.

  3. Electrolytes for Low-Temperature Operation of Li-CFx Cells

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

    2009-01-01

    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.

  4. Solvent-Dictated Lithium Sulfur Redox Reactions: An Operando UV-vis Spectroscopic Study.

    Zou, Qingli; Lu, Yi-Chun

    2016-04-21

    Fundamental understanding of solvent's influence on Li-S redox reactions is required for rational design of electrolyte for Li-S batteries. Here we employ operando UV-vis spectroscopy to reveal that Li-S redox reactions in high-donor-number solvents, for example, dimethyl sulfoxide (DMSO), undergo multiple electrochemical and chemical reactions involving S8(2-), S6(2-), S4(2-), and S3(•-), where S3(•-) is the most stable and dominant reaction intermediate. In low-donor-number solvents, for example, 1,3-dioxolane:1,2-dimethoxyethane, the dominant reaction intermediate, is found to be S4(2-). The stability of these main polysulfide intermediates determines the reaction rates of the disproportionation/dissociation/recombination of polysulfides and thereby affects the reaction rates of the Li-S batteries. As an example, we show that dimethylformamide, a high-donor-number solvent, which exhibits stronger stabilization of S3(•-) compared with DMSO, significantly reduces Li-S cell polarization compared with DMSO. Our study reveals solvent-dependent Li-S reaction pathways and highlights the role of polysulfide stability in the efficiency of Li-S batteries. PMID:27050386

  5. Discrete magnesium hydride aggregates: a cationic Mg13H18 cluster stabilized by NNNN-type macrocycles.

    Martin, Daniel; Beckerle, Klaus; Schnitzler, Silvia; Spaniol, Thomas P; Maron, Laurent; Okuda, Jun

    2015-03-23

    Large magnesium hydride aggregates [Mg13 (Me3 TACD)6 (μ2 -H12 )(μ3 -H6 )][A]2 ((Me3 TACD)H=1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane; A=AlEt4 , AlnBu4 , B{3,5-(CF3 )2 C6 H3 }4 ) were synthesized stepwise from alkyl complexes [Mg2 (Me3 TACD)R3 ] (R=Et, nBu) and phenylsilane in the presence of additional Mg(II) ions. The central magnesium atom is octahedrally coordinated by six hydrides as in solid α-MgH2 of the rutile type. Further coordination to six magnesium atoms leads to a substructure of seven edge-sharing octahedra as found in the hexagonal layer of brucite (Mg(OH)2 ). Upon protonolysis in the presence of 1,2-dimethoxyethane (DME), this cluster was degraded into a tetranuclear dication [Mg2 (Me3 TACD)(μ-H)2 (DME)]2 [A]2 . PMID:25651417

  6. Chemistry of polyfunctional molecules, 94[1

    The P3-nortricyclane 4-methyl-1,2,6-triphosphatricyclo [2.2.1.02,6]heptane, CH3C(CH2P)3, (1), is synthesized in a better yield than earlier described from P4, a Na/K alloy, and CH3C(CH2Br)3 in boiling 1,2-dimethoxyethane. It reacts with M(CO)5thf (M=Cr,W) in the molar ratios of 1:1, 1:2, and 1:3 to form the pentacarbonylmetal complexes CH3C(CH2P)3[M(CO)5]n [n=1,2,3; M=Cr (a), W (b)], (2a, b-4a, b). 1 gives with Mo(CO)5thf only mixtures of CH3C(CH2P)3[Mo(CO)5]n and cis-Mo(CO)4 derivatives, which were identified by their infrared active A1 v(CO) modes at 2075 and 2025cm-1. All the new compounds have been characterized also by their 1H{31P}, 31P{1H} NMR, IR, Raman, and mass spectra. (Author)

  7. Organic electrolyte for nonaqueous cells

    Blomgren, G.E.; Leger, V.Z.

    1989-02-28

    A nonaqueous electrolyte solution, for nonaqueous cells is described comprising a solute dissolved in a solvent, the solvent comprising at least one diether in which two oxygen atoms are separated by two carbon atoms in the sequence O/sub 1/C/sub 1/C/sub 2/O/sub 2/ and in which two or three contiguous atoms of the sequence are contained in a ring system of five, six or seven members in which the remaining ring atoms are carbon, or carbon and hetero atoms. When the oxygen atom O/sub 1/ or O/sub 2/, or oxygen atoms O/sub 1/ and O/sub 2/, are not included in the ring structure, a methyl group is bonded to the oxygen atom or atoms. The electrolyte solution contains at least one cosolvent selected from the group consisting of sulfolane, 3-methyl sulfolane; tetrahydrofuran; 2-methyltetrahydrofuran; 1,3-dioxolane; 3-methyl-oxazolidone; propylene carbonate; ..gamma.. (gamma)-butyrolactone; ..gamma.. (gamma)-valerolactone; ethylene glycol dimethylsulfite; dimethyl sulfoxide; and 1,1- and 1.2-dimethoxyethane.

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

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

    2016-05-01

    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. PMID:27082642

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

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

    2016-01-26

    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.

  10. Molybdenum complexes derived from the oxydianiline [(2-NH2C6H4)2O]: synthesis, characterization and ε-caprolactone ROP capability.

    Yang, Wenxue; Zhao, Ke-Qing; Redshaw, Carl; Elsegood, Mark R J

    2015-08-01

    The reaction of Na2MoO4 with 2,2'-oxydianiline (2-aminophenylether), (2-NH2C6H4)2O, LH4, in DME (DME = 1,2-dimethoxyethane) in the presence of Et3N and Me3SiCl afforded either the bis(imido) molybdenum(vi) complex {Mo(L)Cl2(DME)} (), where L = (2-NC6H4)2O, or the molybdenum(v) salt [Mo(L')Cl4][Et3NH] (), where L' = [(2-NH2C6H4)(2-NC6H4)O], depending on the work-up method employed. The same diamine reacted with in situ [Mo(NtBu)2Cl2(DME)] afforded a tetra-nuclear complex [Mo4Cl3(NtBu)3(OSiMe3)(μ4-O)(L)2(L')2]·2MeCN (·2MeCN). The crystal structures of , and ·2MeCN have been determined. The structure of the bis(imido) complex contains two unique molecules paired up via weak π-stacking, whereas the structure of contains a chelating amine/imido ligand, and is made up of discrete units of two cations and two anions which are interacting via H-bonding. The tetra-nuclear structure contains four different types of distorted octahedral molybdenum centre, and a bent Me3SiO group thought to originate from the precursor synthesis. Complexes have been screened for their ability to ring open polymerize (ROP) ε-caprolactone. For and (not ), conversion rates were good (>90%) at high temperatures (100 °C) over 6-24 h, and the polymerization proceeded in a living manner. PMID:26107689

  11. One ligand fits all: lanthanide and actinide sandwich complexes comprising the 1,4-bis(trimethylsilyl)cyclo-octa-tetra-enyl (=COT'') ligand

    The series of anionic lanthanide(III) sandwich complexes of the type [Ln(COT'')2]- (COT'' = 1,4-bis(trimethylsilyl)cyclo-octa-tetra-enyl di-anion) has been largely extended by the synthesis of eight new derivatives ranging from lanthanum to lutetium. The new compounds [Li(DME)3][Ln(COT'')2] (Ln = Y (1), La (2), Pr (3), Gd (4), Tm (6), Lu (8)) and [Li(THF)4][Ln(COT'')2] (Ln = Ho (5), Tm (7)) were prepared in good yields following a straightforward synthetic protocol which involves the treatment of LnCl3 with 2 equiv. of in situ prepared Li2COT' in either DME (=1,2-dimethoxyethane) or THF. The neutral actinide sandwich complexes An(COT'')2 (An = Th (9), U (10)) and An(COT''')2 (COT''' = 1,3,6-tris(trimethylsilyl)cyclo-octa-tetra-enyl di-anion; An = Th (11), U (12)) were synthesized in a similar manner, starting from ThCl4 or UCl4, respectively. The COT'' ligand imparts excellent solubility even in low-polar solvents as well as excellent crystallinity to all new compounds studied. All twelve new f-element sandwich complexes have been structurally authenticated by single-crystal X-ray diffraction. All are nearly perfect sandwich complexes with little deviation from the coplanar arrangement of the substituted COT'' rings. Surprisingly, all six [Li(DME)3][Ln(COT)2] complexes covering the entire range of Ln3+ ionic radii from La3+ to Lu3+ are isostructural (space group P1-bar). % Compound 10 is the first uranocene derivative for which 13C NMR data are reported. (authors)

  12. Structural variety in solvated lanthanoid (III) halide complexes

    Treatment of lanthanum metal with CH2Br2 or CH2I2 in tetrahydrofuran (thf) under ultrasound conditions yields the corresponding [LaX3(thf)4] (X Br, I) complexes in good yield. Recrystallization of [LaBr3(thf)4] from 1,2-dimethoxyethane (dme) or bis(2-methoxyethyl) ether (dig-lyme) generates [LaBr2(μ-Br)(dme)2]2 and [LaBr2(dig-lyme)2][LaBr4(diglyme)]. Treatment of lanthanoid metals with hexachloroethane in dme yields [LnCl3(dme)2] (Ln = La, Nd, Er or Yb) and in acetonitrile [YbCl2(MeCN)5]2[YbCl3(MeCN)(-Cl)2YbCl3(MeCN)]. The reaction of Yb metal pieces with 1,2-dibromoethane in thf and dme gave single crystals of [YbBr3(thf)3] and [YbBr3(dme)2], respectively. The X-ray determined structure of [LaBr3(thf)4] shows a seven-coordinate monomer with pentagonal-bipyramidal stereochemistry and apical bromide ligands. For [YbBr3(thf)3], a monomeric structure with mer-octahedral stereochemistry is observed. In [LaBr2(μ-Br)(dme)2]2, two eight-coordinate La centres are linked by two bridging bromides. The dme ligands have a trans relationship to each other, and cis terminal bromides are transoid to the bridging bromides with dodecahedral stereochemistry for La. By contrast, the 1: 1.5 diglyme adduct is found to be ionic [LaBr2(diglyme)2][LaBr4(diglyme)], with an eight-coordinate bicapped trigonal-prismatic lanthanum cation and a seven-coordinate pentagonal-bipyramidal lanthanum anion. In the cation, the bromide ligands are cis to each other, and in the anion, two bromides are equatorial and two are axial. In [YbBr3(dme)2], [YbCl3(dme)2] and [ErCl3(dme)2], a seven-coordinate pentagonal-bipyramidal arrangement exists with apical halogen ligands. Far-infrared data, and in particular the absence of absorptions attributable to I(La-Clter), suggest that [LaCl3(dme)] is polymeric with six bridging chlorides per lanthanum. For [YbCl2(MeCN)5]2[YbCl3(MeCN)(-Cl)2YbCl3-(MeCN)], a remarkable ionic structure, with pentagonal-bipyramidal [YbCl2(MeCN)5]+ cations and octahedral di-nuclear [Yb

  13. Electrochemical hydrogen Storage Systems

    Dr. Digby Macdonald

    2010-08-09

    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

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

    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

  15. Electrochemical hydrogen Storage Systems

    Dr. Digby Macdonald

    2010-08-09

    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

  16. Electrochemical hydrogen Storage Systems

    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 halides. To enable a