The structures of alkalides and electrides. V. Structures of caesium bis(15-crown-5) kalide and rubidium bis(15-crown-5) rubidide

Ward, D. L.; Huang, Rui; Dye, James

doi:10.1107/s0108270190002293

Cited by 21 publications

(10 citation statements)

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“…The X-ray crystallographic structures − reveal that there is one or more clear crystal void(s) in each of the organic electrides, with diameters of 0.4–0.6 nm. This suggests the presence of crystal voids as the first potential descriptor for identification of electride materials.…”

Section: Organic Electridesmentioning

confidence: 99%

“…Since this time, six additional organic electrides, consisting of alkali metals complexed to crown ether or cryptand ligands, have been synthesized and characterized. − This was followed by the isolation of the first inorganic electride, [Ca 24 Al 28 O 64 ] 4+ (4e – ), in 2003 by Matsuishi et al In 2009, researchers also identified a previously predicted electride phase of sodium under extremely high pressure . Since 2013, the field has seen a significant acceleration in the rate of electride discovery and variety, with the characterization of eight additional inorganic electrides, ,− including the 2D layered electrides, [Ca 2 N] + e – and [Y 2 C] + e – . , Definition: An electride is an ionic substance in which the anionic species is a stoichiometrically localized electron. Problem: To date, the presence of localized electrons can only be inferred from experimental results, not directly measured. …”

Section: Introductionmentioning

confidence: 99%

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Theoretical Descriptors of Electrides

Dale

Johnson

2018

J. Phys. Chem. A

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Electrides are ionic substances in which the anionic species is stoichiometrically replaced with localized electrons that reside within crystal voids. Originally discovered in 1983, the past decade has seen a sharp rise in the number of known electride materials, most notably the isolation of the first air- and water-stable electride. As the presence of localized interstitial electrons cannot be directly detected experimentally, researchers have turned to density-functional theory (DFT) to discover new electrides. In this work, we survey eight common theoretical descriptors of electrides for their efficacy in identifying these materials. Illustrative examples are presented for all classes of electrides: organic, inorganic, 2D, elemental, and molecular electrides. In general, density-based descriptors such as the electron localization function (ELF) and localized-orbital locator (LOL) are shown to be the most consistently reliable. Limitations of DFT treatments of electrides are also discussed.

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Section: Organic Electridesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Descriptors of Electrides

Dale

Johnson

2018

J. Phys. Chem. A

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“…In 1983, Ellaboudy et al synthesized the first stable crystalline organic electride Cs + (18-crown-6) 2 e – , and in 2003, the first inorganic stable electride [Ca 24 Al 28 O 64 ] 4+ ·(4e – ) was synthesized by Matsuishi et al For these systems, the trapped electrons are located at void spaces of these respective crystals. Later, six air- and temperature-stable organic electrides have been synthesized and characterized. − In all of these electrides, the alkali metals are complexed with the cryptand ligands or crown ethers. The presence of loosely bound confined electrons makes electride systems more interesting because of some remarkable properties, such as high reducing power, high nonlinear optical (NLO) properties, , superconductivity, and electron-emitting characteristics .…”

Section: Introductionmentioning

confidence: 99%

Electride Characteristics of Some Binuclear Sandwich Complexes of Alkaline Earth Metals, M₂(η⁵-L)₂(M = Be, Mg; L = C₅H₅^–, N₅^–, P₅^–, As₅^–)

Das

Chattaraj

2020

J. Phys. Chem. A

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Ab initio calculations have been performed for a series of binuclear sandwich complexes, M 2 (η 5 -L) 2 . It has been observed that the eclipsed and staggered conformations have almost equal amount of energies. The M−M bond lengths are comparable with those in the free M 2 molecules (M = Be, Mg). The nuclear-independent chemical shift (NICS) values indicate the aromaticity of these complexes. The stability of Be 2 (η 5 -L) 2 complexes is higher than that of the Mg 2 (η 5 -L) 2 complexes. The natural bond orbital (NBO) analysis and electron density descriptors proved the existence of a single covalent M−M bond in an M 2 2+ fragment. It has been observed that each M−M bond contains a non-nuclear attractor (NNA) at the center of the respective bond. The Laplacian of electron density [∇ 2 ρ(r)] is negative at the NNAs. The energy decomposition analysis (EDA) showed that M 2 2+ and 2L − represent the bonding interaction in the complexes. All of the designed binuclear sandwich complexes behave as electrides.

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“…In both cases, the excess electrons are confined in the empty area of those crystals. This is followed by the synthesis and characterization of six temperature and air-stable electride systems ( Ward et al, 1988 , Ward et al,1990a ; Ward et al, 1990b ; Wagner et al, 1994 ; Huang et al, 1997 ; Xie et al, 2000 ; Redko et al, 2005 ). In these systems, the cryptand ligands or crown ethers are complexed with alkali metals.…”

Section: Introductionmentioning

confidence: 99%

Comparison Between Electride Characteristics of Li3@B40 and Li3@C60

Das

Chattaraj

2021

Front. Chem.

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Density functional theory (DFT) based computation is performed on the endohedrally encapsulated Li3 cluster inside the B40 and C60 cages namely, Li3@B40 and Li3@C60. For both these systems, the Li-Li bond lengths are shorter than that in the free Li3 cluster. Due to confinement, the Li-Li vibrational frequencies increase in both the systems as compared to that in the free Li3 cluster. Thermodynamically, the formation of these two systems is spontaneous in nature as predicted by the negative values of Gibbs’ free energy changes (ΔG). For both the systems one non-nuclear attractor (NNA) is present on the middle of the Li3 cluster which is predicted and confirmed by the electron density analysis. The NNA population and the percentage localization of electron density at the NNA of the Li3@C60 system are higher than that in the Li3@B40 system. At the NNA the values of the Laplacian of electron density are negative and an electron localization function basin is present at the center of the Li3 cluster for localized electrons. Both systems show large values of nonlinear optical properties (NLO). Both the Li3 encapsulated endohedral systems behave as electrides. Electrides have low work function and hence have a great potential in catalytic activity toward the activation of small molecules (such as CO2, N2). Even some electrides have greater catalytic activity than some well-studied metal-loaded catalysts. As the systems under study behave as electrides, they have the power to show catalytic activity and can be used in catalyzing the activation of small molecules.

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The structures of alkalides and electrides. V. Structures of caesium bis(15-crown-5) kalide and rubidium bis(15-crown-5) rubidide

Cited by 21 publications

References 4 publications

Theoretical Descriptors of Electrides

Theoretical Descriptors of Electrides

Electride Characteristics of Some Binuclear Sandwich Complexes of Alkaline Earth Metals, M₂(η⁵-L)₂(M = Be, Mg; L = C₅H₅^–, N₅^–, P₅^–, As₅^–)

Comparison Between Electride Characteristics of Li3@B40 and Li3@C60

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The structures of alkalides and electrides. V. Structures of caesium bis(15-crown-5) kalide and rubidium bis(15-crown-5) rubidide

Cited by 21 publications

References 4 publications

Theoretical Descriptors of Electrides

Theoretical Descriptors of Electrides

Electride Characteristics of Some Binuclear Sandwich Complexes of Alkaline Earth Metals, M2(η5-L)2(M = Be, Mg; L = C5H5–, N5–, P5–, As5–)

Comparison Between Electride Characteristics of Li3@B40 and Li3@C60

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Electride Characteristics of Some Binuclear Sandwich Complexes of Alkaline Earth Metals, M₂(η⁵-L)₂(M = Be, Mg; L = C₅H₅^–, N₅^–, P₅^–, As₅^–)