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

Abstract

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.

Demonstrating the Potential of Alkali Metal-Doped Cyclic C6O6Li6 Organometallics as Electrides and High-Performance NLO Materials

“…Interest in designing high-performance nonlinear optical (NLO) materials is growing rapidly due to their widespread applications in optical computing, − optical communication, , optical switching, , optical logic functions, , dynamic image processing, , and many other optoelectronic fields. − Recently, a unique class of compounds known as electrides having isolated excess electrons has garnered great interest from the chemical society. − Due to this nontrivial electronic structure, they are easily polarizable and can serve as superior nonlinear optical materials. ,, Electrides due to their certain interesting properties such as the ultralow work function, relatively high catalytic activity, high electronic mobility, and optical and anisotropic properties have great potential for various applications. − In 1983, Dye and co-workers fabricated the first organic crystalline electride consisting of organic complexant cages in which alkali metals and electrons were trapped . Since then, various organic and inorganic electrides have been reported in literature, and their novel electronic structures have been investigated both computationally and experimentally. − …”

Atomic Clusters: Structure, Reactivity, Bonding, and Dynamics

“…This system is further stabilized by sandwiching it between two K@crown-6ether + [K@CE] + counter cations. Again, the C 60 cage trapping a magnesium dimer (Mg 2 @C 60 ) and a lithium trimer (Li 3 @C 60 ) (Das and Chattaraj, 2021a)…”

Computational mining of endohedral C70 electrides: tri-metal alkali and alkaline-earth encapsulation

“…[17][18][19] Current predictions of fullerene-based electrides pursue the large nonlinear optical response of fullerenes, such as e − @C 60 F 60 , (Na 3 O) + (e@C 20 F 20 ) − , (K 3 O) + (e@C 20 F 20 ) − , Li 3 @C 60 , and Mg 2 @C 60 . [20][21][22][23] In the design of electrides, the electronegativity of elements is a crucial factor, as it is a direct measure of the ability of an element to attract or donate electrons. 24 Metal elements with low electronegativity have strong electron-donating abilities.…”

“…Using computational methods is a good way to design electrides, and the current computational studies on predicting fullerene-based electrides are mainly focused on pursuing the large nonlinear optical response of fullerenes, such as e − @C 60 F 60 , (Na 3 O) + (e@C 20 F 20 ) − , (K 3 O) + (e@C 20 F 20 ) − , Li 3 @C 60 , and Mg 2 @C 60 . [20][21][22][23] From the theoretical perspective, density functional theory calculations can relatively better predict electronic behavior in molecules and solids. 25 Electrides can be accurately identified and characterized by calculating the following properties: (a) the existence of non-nuclear attractors (NNAs) of electron density, (b) the Laplacian value of the electron density (∇ 2 ρ) at NNAs is negative, (c) the existence of an electron localization function (ELF) basin, and (d) large nonlinear optical responses.…”