Chemistry of carbanions. XXVIII. Carbon-13 nuclear magnetic resonance spectra of metal enolates

House, Herbert O.; Prabhu, Ananth V.; Phillips, William V.

doi:10.1021/jo00869a027

Cited by 80 publications

(21 citation statements)

References 6 publications

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“…Previously, Han et al reported the changes of chemical shifts of a fused cyclic compound to the more shielded region during a discharge cycle . In addition, lithium enolates with less conjugated structures are also observed in the lower frequency region . It is noteworthy that labeled 13 C‐1 and 13 C‐1' are solely detected as shown in Figure c.…”

Section: Resultsmentioning

confidence: 78%

Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Lee

Park

Kim

et al. 2015

Adv Funct Materials

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4859wileyonlinelibrary.com low maintenance costs, and high energy densities, in order to replace nuclear energy or fi nite supplies of fossil fuels. Lithium-ion battery (LIB) technologies are considered to be promising candidates to meet those demands. [ 3,4 ] While most electrode materials in LIBs are based on inorganic elements or compounds, redox-active organic materials have recently gained attention as a fascinating class due to their ecofriendly production starting from renewable resources (biomass or natural compounds) and solution-phase reactions that avoid high-energy ceramic processes. [5][6][7][8][9] Moreover, the structural diversity of the organic building blocks (as scaffolds and substituents) allows the rational design of highperformance electrode materials. [10][11][12] The Chen group proposed a molecular-level engineering strategy to improve cell performance with respect to working potential, power density, rate capability, and cycling stability through the incorporation of fused heterocyclic moieties and pre-aromatic 1,2-dicarbonyl functional groups. [ 13,14 ] Ever since the fi rst demonstration of a primary battery utilizing organic molecules by Williams et al. in 1969, [ 15 ] new classes of organic materials have been developed for secondary batteries; these include conducting polymers, nitroxide-bearing radical polymers, disulfi des, and quinone derivatives. [16][17][18][19] In 2009, the seminal work of Tarascon and co-workers introduced organic anode materials on the basis of conjugated dicarboxylates including dilithium terephthalate (Li 2 TP) and dilithium trans , trans -muconate. [ 20 ] The organic salts exhibited excellent electrochemical performance in terms of enhanced thermal stability, good cyclability, and suitable redox potential. As shown in Scheme 1 a, Li 2 TP reacts with two lithium atoms to afford a conjugated enolate with a reversible capacity of about 300 mA h g −1 . According to Hünig's classifi cation, the carboxylate-enolate interconversion of Li 2 TP belongs to an inverseWurster-type system, where carboxylates are located outside a cyclic π-system that has aromaticity in the oxidized state. [ 21 ] Despite noteworthy progress, the utilization of organic-based materials involving two-electron insertion process is practically limited due to relatively low specifi c capacity values. Mechanistic Studies of Transition Metal-Terephthalate Coordination Complexes upon Electrochemical Lithiation and DelithiationHyun Ho Lee , Yuwon Park , Su Hwan Kim , Sun-Hwa Yeon , Sang Kyu Kwak , Kyu Tae Lee , * and Sung You Hong * Redox-active organic molecules are intriguing candidates as active electrode materials for next-generation rechargeable batteries due to their structural diversity, environmental friendliness, and solution-phase preparation processes. Recently, a transition metal-organic coordination approach is exploited to construct high capacity anodes for lithium-ion rechargeable batteries. Here, a family of transition metal-organic coordination complexes with terephthalate li...

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Section: Resultsmentioning

confidence: 78%

Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Lee

Park

Kim

et al. 2015

Adv Funct Materials

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“…This complexation is, however, not strong enough to result in the complete deaggregation of MiBLi in THF. House et al [91] studied the effect of DME and several crown ethers on the 13 C NMR spectrum of the Li enolate 9 in THF (Scheme 14). Consistently, no significant change in the chemical shifts was reported.…”

Section: Scheme 13 Polyether and Polyamine Ligands Used In Lapmentioning

confidence: 99%

Anionic polymerization of methacrylic monomers: characterization of the propagating species

Zune

Jérôme

1999

Progress in Polymer Science

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Ligation of the anionic species responsible for the polymerization (LAP) of alkyl(meth)acrylates has much contributed to improve polymerization control. This ligated anionic polymerization has been firstly studied by using model compounds, such as low molecular weight lithium ester enolates. Recently, effort has been devoted to the direct analysis of the species that propagate the anionic polymerization of (meth)acrylates. In addition to IR, multinuclear NMR spectroscopy has been very instrumental in the elucidation of the structure and aggregation of the active species and how these characteristic features are modified by the addition of various types of ligands. This substantial progress in the characterization of the polyalkyl(meth)acrylate anions, ligated or not, is reported in this review.

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“…House et ul. (8). In the structurally related enamines, methyl substitution effects at C-1 and C-4 are also remarkably similar (9).…”

Section: A Alditninesmentioning

confidence: 99%

¹³C lithiation shifts in aldimines and ketimines. Evidence on the configuration of lithiated N-tert-butylimines

Fraser¹,

Chuaqui-Offermanns²

1981

Can. J. Chem.

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ROBERT R. FRASER and NOEMI CHUAQUI-OFFERMANNS. Can. J. Chem. 59,3007 (1981). The "C shieldings for a series of aldimines and ketimines have been measured along with the shifts for their 1-lithio derivatives. For those aldimines with a primary or secondary alkyl group attached to nitrogen, the "lithiation shifts" for the attached carbon (C-4) were all upfield due to the change from anti to syn configuration on lithiation. In the ketimines and in the N-tert-butyl aldimines and ketimines. the lithiation shifts for the C-4 carbon failed to provide stereochemical information. The shifts at C-1 and C-2 proved similar to those previously observed for lithiated alkenes.ROBERT R. FRASER et NOEMI CHUAQUI-OFFERMANNS. Can. . I . Chem. 59, 3007 (1981). On a mesure les blindages du I3C d'une serie d'aldimines et de cetimines ainsi que les deplacements chimiques de leurs derives lithies en position 1. Pour les aldimines ayant un groupe alkyle primaire ou secondaire fixe sur I'azote, les deplacements conduits par la lithiation du carbone (C-4) se font tous vers les champs forts par suite d'un changement de configuration de anti a syn lors de la lithiation. Dans le cas des cetimines, des N-butylaldimines et cetimines, les deplacements provoques par la lithiation sur le carbone en position 4 n'ont pas apporte d'information sur la stereochimie. Les deplacements chimiques des carbones en positions 1 et 2 sont identiques a ceux observes anterieurement pour les derives lithies des aicenes.[Traduit par ie journal]In a series of studies of the stereochemistry of lithiation and alkylation of aldimines and ketimines, we have described evidence for a very marked energetic preference for the formation of a synl lithiated intermediate on the basis of formation of syn alkylation pmducts (1, 21, a b initio calculations (31, and the observation of extraordinarily large barriers to rotation about the N-C-4 single bond of several 1-lithio-3-azapent-2-enides (4). Distinction between configurations at the C=N bond of these imines having the formulae shown below is readily provided by the large syn-anti differential shielding which appears as preferential upfield shifts of 5 to 11 ppm ( 5 ) for either C-1 or C-4 when syn to each other.In this paper we wish to describe the 13C shielding parameters for a variety of lithiated imines. Comparison with the shieldings of their neutral precursors provides a measure of the "lithiation shifts" whose magnitudes appear to be significantly influenced by substituent effects and by the stereochemistry at the C=N bond. A more unique class of sterically congested aldimines and ketimines bearing an N-tert-butyl substituent was also studied. One of these, acetone N-tert-butylimine was observed to undergo lithiation and methylation to give only syn product, indicative of a syrz lithiated intermediate. Unfortunately, similar alkylation experiments on N-tert-butylaldimines were i n c~n c l u s i v e .~ Measurement of the I3C spectra of these aldimines and lithio derivatives gave "lithiation shift" data which failed to p...

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Chemistry of carbanions. XXVIII. Carbon-13 nuclear magnetic resonance spectra of metal enolates

Cited by 80 publications

References 6 publications

Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Anionic polymerization of methacrylic monomers: characterization of the propagating species

¹³C lithiation shifts in aldimines and ketimines. Evidence on the configuration of lithiated N-tert-butylimines

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Chemistry of carbanions. XXVIII. Carbon-13 nuclear magnetic resonance spectra of metal enolates

Cited by 80 publications

References 6 publications

Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Mechanistic Studies of Transition Metal‐Terephthalate Coordination Complexes upon Electrochemical Lithiation and Delithiation

Anionic polymerization of methacrylic monomers: characterization of the propagating species

13C lithiation shifts in aldimines and ketimines. Evidence on the configuration of lithiated N-tert-butylimines

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¹³C lithiation shifts in aldimines and ketimines. Evidence on the configuration of lithiated N-tert-butylimines