On the existence and characterization of molecular electrides

Postils, Verònica; Garcia‐Borràs, Marc; Solà, Miquel; Luis, Josep M.; Matito, Eduard

doi:10.1039/c5cc00215j

Cited by 73 publications

(145 citation statements)

References 34 publications

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“…Three criteria have been proposed as necessary conditions in topological analyses of molecular electrides [61]: a nonnuclear maximum (NNM) of the electron density, a valence ELF basin, and negative values of the Laplacian of the electron density. While these criteria are fulfilled in the hP 4 and oP 8 phases of Na and K, they also fit other nonelectride metallic phases.…”

Section: A Electridesmentioning

confidence: 99%

Structural and electronic properties of the alkali metal incommensurate phases

Woolman

Robinson

Marqués

et al. 2018

Phys. Rev. Materials

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Under pressure, the alkali elements sodium, potassium, and rubidium adopt nonperiodic structures based on two incommensurate interpenetrating lattices. While all elements form the same "host" lattice, their "guest" lattices are all distinct. The physical mechanism that stabilizes these phases is not known, and detailed calculations are challenging due to the incommensurability of the lattices. Using a series of commensurate approximant structures, we tackle this issue using density functional theory calculations. In Na and K, the calculations prove accurate enough to reproduce not only the stability of the host-guest phases, but also the complicated pressure dependence of the host-guest ratio and the two guest-lattice transitions. We find Rb-IV to be metastable at all pressures, and suggest it is a high-temperature phase. The electronic structure of these materials is unique: they exhibit two distinct, coexisting types of electride behavior, with both fully localized pseudoanions and electrons localized in 1D wells in the host lattice, leading to low conductivity. While all phases feature pseudogaps in the electronic density of states, the perturbative free-electron picture applies to Na, but not to K and Rb, due to significant d-orbital population in the latter.

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Section: A Electridesmentioning

confidence: 99%

Structural and electronic properties of the alkali metal incommensurate phases

Woolman

Robinson

Marqués

et al. 2018

Phys. Rev. Materials

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“…When Li atom is intercalated in calix[4]pyrrole (Figure ), its s ‐electron is pushed away from the alkali metal due to the action of the nitrogen‐atom lone pairs in the pyrrole rings. There is a negative value in Laplacian basin outside of the pyrrole rings and alkali atom, thus Li@calix[4]pyrrole shows an electride‐like characteristics, and this picture is corroborated by the finding of a NNA basin below the pyrrole rings …”

Section: Computational Characterizationmentioning

confidence: 76%

Section: Computational Characterizationmentioning

confidence: 99%

Electride: from computational characterization to theoretical design

Zhao

Kan

2016

WIREs Comput Mol Sci

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Electrides are a class of materials in which anionic electrons are spatially separated from the positively charged crystalline framework. With such a unique structure, electrides show great potential in various applications, such as superconductivity, electronics, and catalysis. A number of organic and inorganic electrides have been successfully synthesized in experiment, and their novel electronic structures are studied both computationally and experimentally. Computational characterization can provide information which is difficult to be obtained from experiment. In electronic structure calculations, charge density, noncovalent interaction (NCI) index, electron localization function (ELF), and electrostatic potential (ESP) can be analyzed to identify anionic electrons in confined space. On the other hand, theoretical studies can also be used to design new electrides, such as in a recent instance of two-dimensional (2D) electride screening. Alternatively, new applications and novel electron systems based on electrides can be explored theoretically. As an example, based on Ca 2 N electride, an intrinsic 2D electron gas system in free space (2DEG-FS) has been proposed. With the aid of computational characterization and theoretical design, electride study will continue to be an important field in materials science.

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“…Thus modeling and synthesis of temperature and air‐stable electrides are always demanding. The characterization of electrides and to know the location of the free electrons (or a significant portion of an electron with high localization) are still very challenging for the experimental procedure , . The first principle computational studies can help a way out at this point.…”

Section: Introductionmentioning

confidence: 99%

“…The first principle computational studies can help a way out at this point. Sola and co‐workers and Dale et al have studied several molecular electrides and identified criteria to classify an electride as, (i) the existence of non‐nuclear attractors (NNA) of the electron density,, , i.e., a (3,–3) type of critical point (CP) in the molecular graph but not at the nuclear positions; (ii) presence of electron localization function (ELF) basins, , at the same region where NNAs exist; (iii) the Laplacian of the electron density [∇ 2 ρ( r )] should be negative at these NNAs; (iv) high NLO properties;, , , (v) non‐covalent interaction (NCI) index, , to identify the confined electrons. Although it is stated that the presence of NNA with negative ∇ 2 ρ( r ) is sufficient, but we will focus on all of the five properties mentioned above to characterize our system as an electride material.…”

Section: Introductionmentioning

confidence: 99%

A Complex Containing Four Magnesium Atoms and Two Mg–Mg Bonds Behaving as an Electride

2019

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Herein, we report for the first time the stabilization of two Mg(I)–Mg(I) bonds simultaneously in the same complex. The β‐diketeminate based ligand is modified computationally and a new class of ligand, DippHL (Dipp = 2,6‐diisopropylphenyl) is designed that can hold two Mg atoms. Two such ligands stabilize two Mg22+ ions in a planar configuration and [Mg4(DippHL)2]2– complex is formed. Formation of a synthetically viable neutral [Mg4(DippHL)2]2–·2[K@CE]+ (CE = 18‐crown‐6 ether) complex is possible with the reduction of a proper precursor‐like [Mg2(DippHL)I2]– with potassium metals in toluene solvent and the reaction is exothermic in nature. The computed Mg–Mg bond lengths are in close agreement with that of the Mg–Mg single bond. The results obtained from natural bond orbital (NBO) and atoms in molecule (AIM) analyses confirm the presence of two Mg–Mg bonds in the complex. The complex under study has fulfilled all of the desired criteria and proved itself to be termed as an electride.

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On the existence and characterization of molecular electrides

Cited by 73 publications

References 34 publications

Structural and electronic properties of the alkali metal incommensurate phases

Structural and electronic properties of the alkali metal incommensurate phases

Electride: from computational characterization to theoretical design

A Complex Containing Four Magnesium Atoms and Two Mg–Mg Bonds Behaving as an Electride

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