23Na NMR spectrum of the sodium anion

Ceraso, Joseph M.; Dye, James

doi:10.1063/1.1682119

Cited by 52 publications

(28 citation statements)

References 27 publications

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“…This led, in 1974, to the formation and crystal structure determination of the first crystalline salt of an alkali metal anion, Na + (C222)Na − [23]. The solid-state 23 Na NMR spectrum [24] confirmed the identification of Na − as the anion. Comparison with the structure and interatomic distances in the compound Na + (C222)I − [25] provided us further confirmation that Na − is a large spherical anion.…”

Section: The Third Surprise: Alkali Metal Anionsmentioning

confidence: 98%

The alkali metals: 200 years of surprises

Dye

2015

Phil. Trans. R. Soc. A.

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Section: The Third Surprise: Alkali Metal Anionsmentioning

confidence: 98%

The alkali metals: 200 years of surprises

Dye

2015

Phil. Trans. R. Soc. A.

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“…Due to their fascinating properties, numerous studies of alkalide ions and related systems have been carried out. − For example, reacting alkali metal solutions with cryptands has led to the discovery of crystalline salts of complexed alkalide ions. Dye and coworkers isolated and characterized Na + /Na – salts with the 2.2.2 cryptand, viz., [Na + [2.2.2]cryptand Na – ], , which has been thoroughly characterized. We abbreviate this system as [Na + c222Na – ] in the following.…”

mentioning

confidence: 99%

“…NMR spectroscopy provided the first unequivocal proof of the existence of alkalide ions in solutions and solids. − The resolution of the NMR experiment allows for the simultaneous identification of both the anion and the complexed cation. For instance, 23 Na NMR chemical shifts have been measured for [Na + c222Na – ] on several occasions. ,,, The chemical shift of Na + in this system is typical of the shift detected for other sodium salts.…”

mentioning

confidence: 99%

The Sodium Anion Is Strongly Perturbed in the Condensed Phase Even Though It Appears Like a Free Ion in Nuclear Magnetic Resonance Experiments

Abella

Philips

Autschbach

2020

J. Phys. Chem. Lett.

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Solvated sodium anions (Na − ) were thought to behave essentially like isolated gas-phase ions that interact only weakly with their environments. For example, 23 Na NMR signals for solvated Na − are very sharp, despite the potential for strong quadrupolar broadening. The sharp NMR signals appear to indicate a nearly spherical electron density of the ion. For the present study, ab initio molecular dynamics simulations and quadrupolar relaxation rate calculations were carried out for the Na − /Na + [2.2.2]cryptand system solvated in methylamine, followed by detailed analyses of the electric field gradient at the sodium nuclei. It is found that Na − does not behave like a quasi-free ion interacting only weakly with its environment. Rather, the filled 3s shell of Na − interacts weakly with the ion's own core and the nucleus, causing Na − to appear in NMR experiments like a free ion.

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“…The NMR signatures of an alkalide species in solution, and in the crystalline solids they form, are significantly shielded and exhibit an exceptionally narrow line width. Considering that the alkali metals all possess quadrupolar nuclei, these features have been ascribed to the high shielding and high symmetry of an unperturbed “gaslike” anion in solution, with little to no interaction with its local environment. − However, the high polarizability of the alkalides and ready electron dissociation into solvated-electron species with increasing solvent polarity imply that the genuine alkalide could be significantly perturbed in certain cases. Indeed, the “gaslike” picture of alkalides in solution has recently been questioned by ab initio calculations, which have instead provided two insights in favor of a picture of an alkalide interacting with its environment: First, it was suggested that the most stable species were formed via the association of the alkalide anion with solvated/complexed alkali cations in a known alkalide-forming solvent, 1,2-ethylenediamine, and it was shown that the simulated absorption spectra for such interacting species in the visible and ultraviolet ranges were in agreement with experimental observations.…”

Section: Introductionmentioning

confidence: 99%

Superalkali–Alkalide Interactions and Ion Pairing in Low-Polarity Solvents

et al. 2021

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The nature of anionic alkali metals in solution is traditionally thought to be “gaslike” and unperturbed. In contrast to this noninteracting picture, we present experimental and computational data herein that support ion pairing in alkalide solutions. Concentration dependent ionic conductivity, dielectric spectroscopy, and neutron scattering results are consistent with the presence of superalkali–alkalide ion pairs in solution, whose stability and properties have been further investigated by DFT calculations. Our temperature dependent alkali metal NMR measurements reveal that the dynamics of the alkalide species is both reversible and thermally activated suggesting a complicated exchange process for the ion paired species. The results of this study go beyond a picture of alkalides being a “gaslike” anion in solution and highlight the significance of the interaction of the alkalide with its complex countercation (superalkali).

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23Na NMR spectrum of the sodium anion

Cited by 52 publications

References 27 publications

The alkali metals: 200 years of surprises

The alkali metals: 200 years of surprises

The Sodium Anion Is Strongly Perturbed in the Condensed Phase Even Though It Appears Like a Free Ion in Nuclear Magnetic Resonance Experiments

Superalkali–Alkalide Interactions and Ion Pairing in Low-Polarity Solvents

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