Solvated Electron Pairing with Earth Alkaline Metals in THF. 1. Formation and Structure of the Pair with Divalent Magnesium

Renou, F.; Mostafavi, Mehran; Archirel, Pierre; Bonazzola, L.; Pernot, Pascal

doi:10.1021/jp0216124

Cited by 22 publications

(70 citation statements)

References 35 publications

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“…18 A similar phenomenon has been reported experimentally in the case of earth alkaline cations and an excess electron in THF. 10,37 Furthermore, the presence of this shoulder on the spectrum of the solvated electron near a sodium cation has been reported in an experimental study by Gelabert and Gauduel. 9…”

Section: Absorption Spectrummentioning

confidence: 55%

“…[4][5][6][7][8] In such systems, water mediates the effective interactions between the ion and the excess electron and the formation of contact pairs was suggested. 6,9,10 Electron spin echo spectroscopy studies gave indirect information on the structure of the solvation shell of a solvated electron in alkaline glasses and ice. [11][12][13] Recent resonance Raman spectra in bulk water supported these structural findings.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulations of Electron−Alkali Cation Pairs in Bulk Water

2005

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The structural, dynamic, and thermodynamic properties of an excess electron interacting with an alkali cation (Na+, K+, Li+) in bulk water were investigated by means of a mixed quantum-classical molecular dynamics simulation technique. This study includes a reparametrization of the electron-cation pseudopotentials. The free energy calculations for all three systems show that a contact electron-cation pair can be observed, which is either as stable as the dissociated pair (Li+) or more stable by only a few kT (Na+, K+). Given that the dissociation barrier is also quite small, we suggest that the average cation-electron distance in the experiments at room temperature will not depend on this free energy profile but rather on the minimization of the Coulombic repulsive interaction between like charges in the solvent medium. This enables us to compare the present molecular dynamics simulations with the spectroscopic data obtained for different ionic strengths. The overall trend of the UV-vis hydrated absorption spectra, namely, the shift toward shorter wavelengths at high ionic strengths, is fairly well reproduced. This confirms our hypothesis of statistical distribution of the cations and solvated electrons.

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Section: Absorption Spectrummentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Electron−Alkali Cation Pairs in Bulk Water

2005

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“…8,9 Computer simulations are expected to contribute to the understanding of the difference in behavior between the two opposite cases of silver (Ag ϩ ) and sodium cation (Na ϩ ) in the presence of an excess electron in bulk water. A recently developed mixed quantum-classical molecular dynamics ͑QCMD͒ approach, based on adiabatic simulation technique, was used to simulate an excess electron in bulk water.…”

Section: Introductionmentioning

confidence: 99%

Molecular dynamics simulations of the Ag+ or Na+ cation with an excess electron in bulk water

Spezia

Nicolas

Archirel

et al. 2004

The Journal of Chemical Physics

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The properties of an excess electron interacting with a monovalent cation in bulk water are studied by molecular dynamics simulations. Sodium and silver cations are chosen as prototypical cases because of their very different redox properties. In both cases, mixed quantum classical molecular dynamics simulations reproduce the experimental UV-Vis spectra. In the case of silver, we observe a highly polarized neutral atom, corresponding to a dipolar excitonic state. For sodium a contact cation/electron pair is observed. Free energy curves along the cation electron coordinate are calculated using quantum Umbrella Sampling technique. The relative stability of the different chemical species is discussed.

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“…Taking into consideration the ability of electrolytes to scavenge free ions, it seems plausible that MgCl 2 , whose dissociation in THF is negligible, 20 can form multiple ions with Li + , as shown in eq. 3 for example.…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Synthesis of Functional Organosilanes II: Direct Electrochemical Formation of Si-C Bonds

Grogger

Loidl

Stueger

et al. 2013

J. Electrochem. Soc.

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Electroreductive Si-C bond formation was used for the formation of organofunctional silanes of the general formula HMe 2 Si-R-Y and MeOMe 2 Si-R-Y (R = alkylene, arylene; Y = H, MeO, Me 2 N, t-BuMe 2 SiO). Employing constant current conditions, different organic halides R-X (R = alkylene, arylene, X = Cl, Br) were electrolyzed in the presence of Me 2 Si(OMe) 2 and HMe 2 SiCl, respectively. All electrolyses were carried out in an undivided cell and with a THF/LiCl (MgCl 2 ) electrolyte. Although both salts are suitable supporting electrolytes, the highest conductivity was obtained with a mixture of LiCl/MgCl 2 = 2/1. It was shown that the reaction proceeds smoothly at current densities between 0.25 and 35 mA cm −2 . Cooling of the electrolysis cell can be omitted.There exist a variety of methods for silicon-carbon bond formation. Examples include the fundamental industrial Direct Process, Grignard-type processes, Wurtz-Fittig coupling reactions and transition metal-catalyzed reactions. 1 One practical method that can be utilized on the laboratory scale is the electrochemical formation of Si-C bonds, which basically involves the reduction of the organic substrate followed by an attack of the electrogenerated C-nucleophile on the Si-Cl bond of a chlorosilane (Scheme 1).In the early 1980s, Shono et al. 2,3 and Yoshida et al. 4 showed that this kind of electroreductive cross-coupling is possible in a divided cell with Pt anodes, but no defined anodic oxidation products were reported. In the great majority of the following papers reporting electrochemical Si-C bond formation, Me 3 SiCl was used as the silyl source. A variety of organic substrates was used with different experimental setups. [5][6][7][8] When di-, tri-or tetrachlorosilanes were used as the electrophiles in stoichiometric quantities, all chlorine substituents on silicon reacted with the electrochemically generated carbanions, thus yielding the corresponding linear, branched or cyclic Si-C compounds. 9-13 There are only a few examples demonstrating that functionality on the silicon atom can be retained: Yoshida et al. 4 reduced cinnamyl chloride in a divided cell with Pt electrodes in the presence of an excess of HMe 2 SiCl. They obtained a mixture of 1,1 and 1,3 silylation products, thus proving the stability of the Si-H bond under electrochemical conditions (Scheme 2).Bordeau et al. electrolyzed several aryl and heteroaryl bromides in the presence of dichlorosilanes R 2 SiCl 2 in an undivided cell with sacrificial anodes. 14-16 They found that a large excess of chlorosilane, a strongly coordinating co-solvent (mostly hexamethyl phosphoric triamide HMPA) and/or a Ni catalyst, had to be used in order to preserve one of the chloro substituents on silicon (cf. Scheme 3).We have been studying the synthesis of organofunctional silanes (OFS) of the general formula X-(Me 2 )Si-R-Y, where X and Y are reactive functional groups and R = alkylene or arylene. With potentially reactive substituents at both silicon and at carbon, these products are useful reactants i...

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Solvated Electron Pairing with Earth Alkaline Metals in THF. 1. Formation and Structure of the Pair with Divalent Magnesium

Cited by 22 publications

References 35 publications

Molecular Dynamics Simulations of Electron−Alkali Cation Pairs in Bulk Water

Molecular Dynamics Simulations of Electron−Alkali Cation Pairs in Bulk Water

Molecular dynamics simulations of the Ag+ or Na+ cation with an excess electron in bulk water

Electrochemical Synthesis of Functional Organosilanes II: Direct Electrochemical Formation of Si-C Bonds

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