- Synthesis and structure of hypercoordinated germanate complexes with naphthalene-2,3-dialkoxide ligands
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The synthesis of six-coordinated germanate complexes with naphthalene-2,3-dialkoxide ligands with alkali metals (Li, Na, and K) as counter ions are described. The molecular structures of lithium and potassium germanate complexes were clarified by X-ray diffraction analysis. Each germanium center atom is coordinated by six oxygen atoms to form slightly distorted octahedral configuration. All the compounds were thermally stable up to 300 °C determined by thermogravimetric analysis under air-flow conditions.
- Goto, Mitsuki,Nakashima, Yuta,Nanjo, Masato
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- The Effect of Water on Quinone Redox Mediators in Nonaqueous Li-O2 Batteries
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The parasitic reactions associated with reduced oxygen species and the difficulty in achieving the high theoretical capacity have been major issues plaguing development of practical nonaqueous Li-O2 batteries. We hereby address the above issues by exploring the synergistic effect of 2,5-di-tert-butyl-1,4-benzoquinone and H2O on the oxygen chemistry in a nonaqueous Li-O2 battery. Water stabilizes the quinone monoanion and dianion, shifting the reduction potentials of the quinone and monoanion to more positive values (vs Li/Li+). When water and the quinone are used together in a (largely) nonaqueous Li-O2 battery, the cell discharge operates via a two-electron oxygen reduction reaction to form Li2O2, with the battery discharge voltage, rate, and capacity all being considerably increased and fewer side reactions being detected. Li2O2 crystals can grow up to 30 μm, more than an order of magnitude larger than cases with the quinone alone or without any additives, suggesting that water is essential to promoting a solution dominated process with the quinone on discharging. The catalytic reduction of O2 by the quinone monoanion is predominantly responsible for the attractive features mentioned above. Water stabilizes the quinone monoanion via hydrogen-bond formation and by coordination of the Li+ ions, and it also helps increase the solvation, concentration, lifetime, and diffusion length of reduced oxygen species that dictate the discharge voltage, rate, and capacity of the battery. When a redox mediator is also used to aid the charging process, a high-power, high energy density, rechargeable Li-O2 battery is obtained.
- Liu, Tao,Frith, James T.,Kim, Gunwoo,Kerber, Rachel N.,Dubouis, Nicolas,Shao, Yuanlong,Liu, Zigeng,Magusin, Pieter C. M. M.,Casford, Michael T. L.,Garcia-Araez, Nuria,Grey, Clare P.
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p. 1428 - 1437
(2018/02/09)
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- Complexes of the gilman reagent with double bonds across the π-σ Continuum
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By using rapid injection NMR at low temperatures, a variety of π-complexes of lithium dimethylcuprate(I) with C-C, C-N, and C-S double bonds have been prepared and characterized. Complexation is generally accompanied by large upfield changes in chemical shift for the substrate carbon atoms bonded to copper. In the case of α,β-unsaturated carbonyl compounds, the changes for the carbonyl carbons are much smaller in magnitude, which is consistent with the usual η2 representation of these structures. It is possible for one ligand to displace another, and in this way an order of stability can be elucidated. Treatment of selected π-complexes with chlorosilanes or cyanosilanes gives CuIII intermediates.
- Bertz, Steven H.,Cope, Stephen K.,Hardin, Richard A.,Murphy, Michael D.,Ogle, Craig A.,Smith, David T.,Thomas, Andy A.,Whaley, Tara N.
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p. 7827 - 7838
(2013/01/16)
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- Dibisyl(fluorenylidene)stannene: evidence of its formation
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The dibisyl(fluorenylidene)stannene 4, obtained by dehydro-chlorination or -fluorination of the corresponding chloro- or fluoro-stannanes 5 and 6 by tert-butyllithium is an extremely air-sensitive compound.It has not been isolated, but identified by trapp
- Anselme, G.,Couret, C.,Escudie, J.,Richelme, S.,Satge, J.
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p. 321 - 328
(2007/10/02)
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- X-ray crystal structure and hydrocarbon solution behaviour of tetrameric 2,2-Bis(methoxymethyl)-1-propyllithium
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The title compound is a tetramer in the solid state and in hydrocarbon solution.
- Moene,Schakel,Hoogland,De Kanter,Klumpp,Spek
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p. 2641 - 2642
(2007/10/02)
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- Competition between Methoxide Attack at Ring-Carbon and at the Cyano-Group of Cyanonitroanisoles. The Effects of Cations.
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Reaction of methoxide ions with the isomeric cyanodinitroanisoles results in competition between attack at ring-carbon and at the cyano-group.Kinetic and equilibrium data are reported for reaction of 4-cyano-2,6-dinitroanisole where rapid formation of the 1,1-dimethoxy adduct is followed by slower equilibration with the imido-ester solvate.The 1,1-dimethoxy adduct is strongly stabilised by association with cations; values of the association constants decrease in the order of cations, Ba(2+) > Ca(2+) > K(+) > Na(+) > Li(+).
- Castilho, Paula C. M. F.,Crampton, Michael R.,Yarwood, Jack
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p. 2801 - 2815
(2007/10/02)
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- On Carbonylnickel and its Reactions with Nucleophiles
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(CDT)NiCO (2), a thermally instable complex previously obtained only in solution, has been isolated and its chemical and spectroscopic properties investigated.The formation of this compound from various different (CDT)NiL complexes suggests that thermodynamically it is relatively stable.Although the CDT can be displaced by other ligands, the carbon monoxide in (CDT)NiCO (2) is not liberated. - On reaction with strong nucleophiles such as lithiumorganyls and -amides, the complexed CO in (CDT)NiCO can be converted to a lithiumacyl or -carbamoyl group.In the resulting (PMDTA)Li(OCR)Ni(CDT) (R = CH3, C6H5, NMe2) (3 - 5) the transition metal is, in addition to the acyl or carbamoyl residue, bound only to an olefin as stabilizing ligand.When R = Me or NMe2, these compounds react further with CO to form the carbonyl-containing lithiumacetyl or -carbamoyl complexes (PMDTA)Li(OCR)Ni(CO)3 (R = Me or NMe2) (6, 7a).Complexes of this type can be prepared from Ni(CO)4 directly only if R = NMe2.
- Poerschke, Klaus Richard,Wilke, Guenther
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- FLUORO-KETONES IV. SYNTHESIS OF PHENYLPERFLUOROALKYL KETONES - MECHANISM OF REACTION BETWEEN PHENYLLITHIUM AND FLUOROESTERS
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Although fluorine containing ketones (RfC(O)Rf and RfC(O)R, Rf = perfluoroalkyl) have been prepared from the reaction between organolithium reagents and perfluoroalkyl esters, the reaction has not found general applicability.Variable yields of ketones and co-production of secondary and tertiary alcohol by-products have in most instances been experienced.We have examined in more detail the factors e.g., temperature, mode of addition and perfluoroalkyl ester structure which influence ketone product and by-products formation.By controlling experimental conditions excellent yields of C6H5C(O)Rf compounds can be attained.A lithium salt of a hemiketal (II) has been isolated and shown to be the active intermediate in the production of the ketone.The stability of the salt and its potential reaction with the solvent dictates the type of reaction products.Low temperature favors stability of the lithium salt of the hemiketal whereby high yields of ketones are produced on hydrolysis.
- Chen, Loomis S.,Chen, Grace. J.,Tamborski, Christ
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p. 117 - 130
(2007/10/02)
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