Magnesium and bromine exafs studies of grignard compounds in solution

Abraham, Ingo; Hörner, W.; Ertel, Teja S.; Bertagnolli, Helmut

doi:10.1016/0277-5387(96)00137-4

Cited by 12 publications

(13 citation statements)

References 10 publications

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“…4a͒ and Mg͑AlCl 2 EtBu͒ 2 /THF ͑Fig. The extracted parameters for the Mg complex in BuMgCl/THF are consistent with those of EtMgBr/n-Bu 2 O, 9 where the small differences seem to come from the different halogens, Cl and Br. Because the tetrahedral structures ͚͑N = 4͒ have already been proved, we fixed the coordination numbers as constant in this study.…”

Section: Resultssupporting

confidence: 71%

“…11 To detect the fluorescence radiation emitted by the sample, a silicon drift detector or a proportional counter with Ar gas was used, which was positioned at an angle of 90°relative to the incident synchrotron radiation. [8][9][10] Theoretical calculations were performed with the program FEFF version 7, with which structural parameters, such as the absorber backscatterer distance r, the coordination num-ber N, and the EXAFS Debye-Waller factor 2 corresponding to the deviation of the backscattering atoms were determined for each EXAFS spectrum by fitting. Electrolyte solutions were sealed in the originally designed highvacuum compatible cells that have the polymer-coated beryllium foil windows ͑5 m Dura Coat, 5 mm , 12 m thick, Brush Wellman͒, whose concept was reported previously.…”

Section: Methodsmentioning

confidence: 99%

“…The conclusion was reached that some concrete complex species, such as MgCl + , Mg 2 Cl 3 +, Et 2 AlCl 2 −, Et 2 AlClTHF, Et 3 AlTHF, 3,7 and Et 4 Al 2 Cl 3 − 4 are formed in the solution. However, as for the case of Mg atoms in solutions, whose K-shell absorption edges ͑ϳ1.3 keV͒ lie in the socalled soft X-ray region, only a few studies have been reported on the structures of Grignard reagents in ether, 9,10 because it is technically hard to obtain large XAFS signals from the liquids, which are sometimes very reactive, under the high-vacuum condition. 3 The X-ray absorption fine structure ͑XAFS͒ method is a powerful tool to investigate complex structures in solutions, revealing the local structure around target atoms via the analysis of X-ray absorption across the energy range for photoemission of K-or L-shell electrons.…”

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confidence: 99%

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Complex Structures and Electrochemical Properties of Magnesium Electrolytes

Nakayama

Kudo

Oki

et al. 2008

J. Electrochem. Soc.

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Magnesium organohaloaluminate in tetrahydrofuran ͓0.25 mol/L Mg͑AlCl 2 EtBu͒ 2 /THF, Et:C 2 H 5 ,Bu:C 4 H 9 ͔ is an electrolyte solution that is able to deposit and dissolve magnesium electrochemically and reversibly at room temperature. It has been reported that the electrochemical window is ruled by Lewis acidity of the aluminum compounds involved, and some complex species formed in the electrolyte have been suggested based on the analysis of nuclear magnetic resonances and Raman spectroscopy. Because in these analytical methods there are not enough controls to identify all the included compounds, neither the complete complex structures nor the mechanism of the reversible reaction has been revealed yet. Here, we show the complete complex structures in this electrolyte directly observed by the X-ray absorption fine structure measurements, which reveal the reversible equilibrium reaction as well as the other electrochemical properties of this electrolyte. A754) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 155.198.30.43 Downloaded on 2015-05-28 to IP A759 Journal of The Electrochemical Society, 155 ͑10͒ A754-A759 ͑2008͒ A759 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 155.198.30.43 Downloaded on 2015-05-28 to IP

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Section: Resultssupporting

confidence: 71%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Complex Structures and Electrochemical Properties of Magnesium Electrolytes

Nakayama

Kudo

Oki

et al. 2008

J. Electrochem. Soc.

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“…Due to its importance in biological processes, interactions of Mg 2+ with macromolecules involved in biotic processes have been examined in considerable detail. ,− Elucidation of the microscopic aspects of such interactions can be achieved using the structure-sensitive methods of NMR or X-ray absorbance spectroscopy (XAS) that can provide important details concerning the number and chemical nature of the atoms surrounding a magnesium atom. − However, these methods require using relatively high concentrations of the target metal and the interpretation of their results may depend on the selection of representative model compounds. ,− Investigation of interactions between Mg 2+ and NOM is also complicated by the fact that NOM is a site-specific polydisperse entity , that has multiple types of proton- and metal-binding groups.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Investigation of Interactions between Magnesium Ion and Natural Organic Matter

Yan

Lü

Gao

et al. 2015

Environ. Sci. Technol.

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Natural organic matter (NOM) generated in all niches of the environment constitutes a large fraction of the global pool of organic carbon while magnesium is one of the most abundant elements that has multiple roles in both biotic and abiotic processes. Although interactions between Mg(2+) and NOM have been recognized to affect many environmental processes, little is understood about relevant mechanisms and equilibria. This study addressed this deficiency and quantified Mg(2+)-NOM interactions using differential absorbance spectroscopy (DAS) in combination with the NICA-Donnan speciation model. DAS data were obtained for varying total Mg concentrations, pHs from 5.0 to 11.0 and ionic strengths from 0.001 to 0.3 mol L(-1). DAS results demonstrated the existence of strong interactions between magnesium and NOM at all examined conditions and demonstrated that the binding of Mg(2+) by NOM was accompanied by the replacement of protons in the protonation-active phenolic and carboxylic groups. The slope of the log-transformed absorbance spectra of NOM in the range of wavelength 350-400 nm was found to be indicative of the extent of Mg(2+)-NOM binding. The differential and absolute values of the spectral slopes were strongly correlated with the amount of NOM-bound Mg(2+) ions and with the concentrations of NOM-bound protons.

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“…A beryllium foil, a silicon nitride (SiN) membrane, and a polyimido (PI) film are often used as X-ray windows of liquid cells and spectro-electrochemical cells in the SX/TX region depending on the intended use. [20][21][22][23][24][25][26][27][28][29] In this study, a 7.5 μm thick PI film coated with 70 nm thick aluminum was adopted as the X-ray window. A PI film was most desirable for their low background nature and mechanical/chemical toughness.…”

Section: Methodsmentioning

confidence: 99%

Novel spectro-electrochemical cell for in situ/operando observation of common composite electrode with liquid electrolyte by X-ray absorption spectroscopy in the tender X-ray region

Nakanishi

Kato

Arai

et al. 2014

Review of Scientific Instruments

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A novel spectro-electochemical cell for X-ray absorption spectroscopy in the tender X-ray region (TX-XAS) was designed and fabricated to investigate the electrochemical behavior of common battery materials with liquid electrolytes under in situ/operando conditions. The cell has several unique features, such as high X-ray transmittance, high signal to noise ratio, and high vacuum tightness. These features enable us quick and reliable XAS measurements. Operando P K-edge XAS measurements of an olivine-type LiFePO4 composite positive electrode were carried out to clarify its phosphorus environment during the electrochemical charging process. Results of spectral analysis show that there is no significant change in the oxidation state of phosphorus and in the coordination of the phosphate anions in the charging process, but a closer look of the consecutive XAS spectra suggests the shrinkage of the PO4 cage during the charging process, and the structural changes in a biphasic manner. These results demonstrate the usefulness of the cell for in situ/operando TX-XAS observations of light elements in practical batteries.

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Magnesium and bromine exafs studies of grignard compounds in solution

Cited by 12 publications

References 10 publications

Complex Structures and Electrochemical Properties of Magnesium Electrolytes

Complex Structures and Electrochemical Properties of Magnesium Electrolytes

In-Situ Investigation of Interactions between Magnesium Ion and Natural Organic Matter

Novel spectro-electrochemical cell for in situ/operando observation of common composite electrode with liquid electrolyte by X-ray absorption spectroscopy in the tender X-ray region

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