Noble gas encapsulated B40 cage

The efficacy of B₄₀ borospherene to act as a host for noble gas atoms is explored via density functional theory based computations. Although the Ng@B₄₀ complexes are thermochemically unstable with respect to dissociation into free Ng and B₄₀, it does not rule out their viability as all the systems possess a high activation free energy barrier (84.7-206.3 kcal mol^-1). Therefore, once they are formed, it is hard to take out the Ng atom. Two Ng atoms can also be incorporated within B₄₀ for the lighter Ng atoms (He and Ne). In fact, the destabilization offered by the encapsulation of one and two He atoms and one Ne atom inside B₄₀ is significantly less than that in experimentally synthesized He@C₂₀H₂₀, highlighting their greater possibility for synthesis. Although Ar₂ and Kr₂ encapsulated B₄₀ systems are very much destabilized by the repulsive interaction between Ng₂ and B₄₀, an inspection of the bonding situation reveals that the confinement can even induce some degree of covalent interaction between two otherwise non-bonded Ng atoms. Ng atoms transfer electrons towards B₄₀ which is smaller for lighter Ng atoms and gradually increases along He to Rn. Even if the electrostatic interaction between Ng and B₄₀ is the most predominant term in these systems, the extent of the orbital interaction is also considerable. However, the very large Pauli repulsion counterbalances the attractive interaction, eventually turning the interaction repulsive in nature. Ng@B₄₀ also shows dynamical behaviour involving continuous exchange between hexagonal and heptagonal holes, similar to the host cage, as understood from the very little variation in the activation barrier because of the Ng encapsulation. Furthermore, sandwich complexes like [(η⁵-C₅Me₅)Fe(η⁶-B₄₀)]⁺ and [(η⁵-C₅Me₅)Fe(η⁷-B₄₀)]⁺ are noted to be viable with the latter being slightly more stable than the former. The encapsulation of Xe slightly improves the dissociation energy associated with the decomposition into Xe@B₄₀ and [Fe(η⁵-C₅Me₅)]⁺ compared to that in the bare one.

Scandium carbides/cyanides in the boron cage: computational prediction of X@B80 (X = Sc2C2, Sc3C2, Sc3CN and Sc3C2CN)

As the first study on metal carbide/cyanide boron clusterfullerenes, the geometries, energies, stabilities and electronic properties of four novel scandium cluster-containing B80 buckyball derivatives, namely Sc2C2@B80, Sc3C2@B80, Sc3CN@B80 and Sc3C2CN@B80, were investigated by means of density functional theory computations. The rather favorable binding energies, which are very close to those of the experimentally abundant carbon fullerene analogues, suggest a considerable possibility to realize these doped boron clusterfullerenes. Their intracluster and cluster-cage bonding natures were thoroughly revealed by various theoretical approaches. In contrast to carbon clusterfullerenes, in which the encaged non-metal atoms mainly play a stabilizing role in the metal clusters, the encapsulated carbon and nitrogen atoms inside the B80 cage covalently bond to the boron framework, resulting in strong cluster-cage interactions. Furthermore, infrared spectra and (11)B nuclear magnetic resonance spectra were simulated and fingerprint peaks were proposed to assist future experimental characterization.

Ultrastable actinide endohedral borospherenes

DFT-PBE0 calculations on AnB_n (An = U, Th; n = 36, 38, and 40) reveal the feasibility of actinide-doped borospherenes.

Boron clusters with 46, 48, and 50 atoms: competition among the core-shell, bilayer and quasi-planar structures

Using a genetic algorithm combined with density functional theory calculations, we perform a global search for the lowest-energy structures of B_n clusters with n = 46, 48, 50. Competition among different structural motifs including a hollow cage, core-shell, bilayer, and quasi-planar, is investigated. For B₄₆, a core-shell B₄@B₄₂ structure resembling the larger B_n clusters with n ≥ 68 is found to compete with a quasi-planar structure with a central hexagonal hole. A quasi-planar configuration with two connected hexagonal holes is most favorable for B₅₀. More interestingly, an unprecedented bilayer structure is unveiled at B₄₈, which can be extended to a two-dimensional bilayer phase exhibiting appreciable stability. Our results suggest alternatives to the cage motif as lower-energy B_n cluster structures with n > 50.

Heteroborospherene clusters Nin ∈ B40 (n = 1-4) and heteroborophene monolayers Ni2 ∈ B14 with planar heptacoordinate transition-metal centers in η7-B7 heptagons

With inspirations from recent discoveries of the cage-like borospherene B₄₀ and perfectly planar Co ∈ B₁₈⁻ and based on extensive global minimum searches and first-principles theory calculations, we present herein the possibility of the novel planar Ni ∈ B₁₈ (1), cage-like heteroborospherenes Ni_n ∈ B₄₀ (n = 1–4) (2–5), and planar heteroborophenes Ni₂ ∈ B₁₄ (6, 7) which all contain planar or quasi-planar heptacoordinate transition-metal (phTM) centers in η⁷-B₇ heptagons. The nearly degenerate Ni₂ ∈ B₁₄ (6) and Ni₂ ∈ B₁₄ (7) monolayers are predicted to be metallic in nature, with Ni₂ ∈ B₁₄ (6) composed of interwoven boron double chains with two phNi centers per unit cell being the precursor of cage-like Ni_n ∈ B₄₀ (n = 1–4) (2–5). Detailed bonding analyses indicate that Ni_n ∈ B₄₀ (n = 1–4) (2–5) and Ni₂ ∈ B₁₄ (6, 7) possess the universal bonding pattern of σ + π double delocalization on the boron frameworks, with each phNi forming three lone pairs in radial direction (3d_z2², 3d_zx², and 3d_yz²) and two effective nearly in-plane 8c-2e σ-coordination bonds between the remaining tangential Ni 3d orbitals (3d_x2−y2 and 3d_xy) and the η⁷-B₇ heptagon around it. The IR, Raman, and UV-vis absorption spectra of 1–5 are computationally simulated to facilitate their experimental characterizations.

Effects of manganese doping on the structure evolution of small-sized boron clusters

Atomic doping of clusters is known as an effective approach to stabilize or modify the structures and properties of resulting doped clusters. We herein report the effect of manganese (Mn) doping on the structure evolution of small-sized boron (B) clusters. The global minimum structures of both neutral and charged Mn doped B cluster [Formula: see text] (n  =  10-20 and Q  =  0, ±1) have been proposed through extensive first-principles swarm-intelligence based structure searches. It is found that Mn doping has significantly modified the grow behaviors of B clusters, leading to two novel structural transitions from planar to tubular and then to cage-like B structures in both neutral and charged species. Half-sandwich-type structures are most favorable for small [Formula: see text] (n  ⩽  13) clusters and gradually transform to Mn-centered double-ring tubular structures at [Formula: see text] clusters with superior thermodynamic stabilities compared with their neighbors. Most strikingly, endohedral cages become the ground-state structures for larger [Formula: see text] (n  ⩾  19) clusters, among which [Formula: see text] adopts a highly symmetric structure with superior thermodynamic stability and a large HOMO-LUMO gap of 4.53 eV. The unique stability of the endohedral [Formula: see text] cage is attributed to the geometric fit and formation of 18-electron closed-shell configuration. The results significantly advance our understanding about the structure and bonding of B-based clusters and strongly suggest transition-metal doping as a viable route to synthesize intriguing B-based nanomaterials.

Structures, stabilities and spectral properties of borospherene B44- and metalloborospherenes MB440/- (M = Li, Na, and K)

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to study the stabilities, photoelectron, infrared, Raman and electronic absorption spectra of borospherene B₄₄⁻ and metalloborospherenes MB₄₄^0/− (M = Li, Na, and K). It is found that all atoms can form stable exohedral metalloborospherenes M&B₄₄^0/−, whereas only Na and K atoms can be stably encapsulated inside B₄₄^0/− cage. In addition, relative energies of these metalloborospherenes suggest that Na and K atoms favor exohedral configuration. Importantly, doping of metal atom can modify the stabilities of B₄₄ with different structures, which provides a possible route to produce stable boron clusters or metalloborospherenes. The calculated results suggest that B₄₄ tends to get electrons from the doped metal. Metalloborospherenes MB₄₄⁻ are characterized as charge-transfer complexes (M²⁺B₄₄²⁻), where B₄₄ tends to get two electrons from the extra electron and the doped metal, resulting in similar features with anionic B₄₄²⁻. In addition, doping of metal atom can change the spectral features, such as blueshift or redshift and weakening or strengthening of characteristic peaks, since the extra metal atom can modify the electronic structure. The calculated spectra are readily compared with future spectroscopy measurements and can be used as fingerprints to identify B₄₄⁻ and metalloborospherenes.

Does the endohedral borospherene supersalt FLi2@B39maintain the “super” properties of its subunits?

The behavior of the entirely unique system represented by superalkaline species incorporated into a superhalogen cage has been studied using density functional theory. The calculations revealed that superhalogen and superalkaline properties inherent in the separated fragments are lost in FLi₂@B₃₉complexes.

Cage-like B39+clusters with the bonding pattern of σ + π double delocalization: new members of the borospherene family

The recently observed cage-like borospherenesD_2dB₄₀^−/0andC₃/C₂B₃₉⁻have attracted considerable attention in chemistry and materials science.

A novel borophene featuring heptagonal holes: a common precursor of borospherenes

We propose a novel stable borophene (referred to as H-borophene) with unique construction pattern, which is able to serve as the common precursor of borospherenes.

Structures, stabilities and spectral properties of metalloborospherenes MB0/−40 (M = Cu, Ag, and Au)

Metalloborospherenes MB0/−40 (M = Cu, Ag, and Au) are predicted. Relative energies of these metalloborospherenes suggest that Cu, Ag and Au atoms favor the exohedral configuration.

Aromatic cage-like B46: existence of the largest decagonal holes in stable atomic clusters

The boron cluster B₄₆has a cage-like structure containing two hexagonal, two heptagonal and two decagonal holes. This finding presents a new family of cage-like boron clusters containing large B_Nholes withN= 6–10.

From Quasi-Planar B56 to Penta-Ring Tubular Ca©B56: Prediction of Metal-Stabilized Ca©B56 as the Embryo of Metal-Doped Boron α-Nanotubes

Motifs of planar metalloborophenes, cage-like metalloborospherenes, and metal-centered double-ring tubular boron species have been reported. Based on extensive first-principles theory calculations, we present herein the possibility of doping the quasi-planar C_2v B₅₆ (A-1) with an alkaline-earth metal to produce the penta-ring tubular Ca©B₅₆ (B-1) which is the most stable isomer of the system obtained and can be viewed as the embryo of metal-doped (4,0) boron α-nanotube Ca©BNT_(4,0) (C-1). Ca©BNT_(4,0) (C-1) can be constructed by rolling up the most stable boron α-sheet and is predicted to be metallic in nature. Detailed bonding analyses show that the highly stable planar C_2v B₅₆ (A-1) is the boron analog of circumbiphenyl (C₃₈H₁₆) in π-bonding, while the 3D aromatic C_4v Ca©B₅₆ (B-1) possesses a perfect delocalized π system over the σ-skeleton on the tube surface. The IR and Raman spectra of C_4v Ca©B₅₆ (B-1) and photoelectron spectrum of its monoanion C_4v Ca©B₅₆⁻ are computationally simulated to facilitate their spectroscopic characterizations.

Lithium-Decorated Borospherene B40: A Promising Hydrogen Storage Medium

The recent discovery of borospherene B₄₀ marks the onset of a new kind of boron-based nanostructures akin to the C₆₀ buckyball, offering opportunities to explore materials applications of nanoboron. Here we report on the feasibility of Li-decorated B₄₀ for hydrogen storage using the DFT calculations. The B₄₀ cluster has an overall shape of cube-like cage with six hexagonal and heptagonal holes and eight close-packing B₆ triangles. Our computational data show that Li_m&B₄₀(1-3) complexes bound up to three H₂ molecules per Li site with an adsorption energy (AE) of 0.11-0.25 eV/H₂, ideal for reversible hydrogen storage and release. The bonding features charge transfer from Li to B₄₀. The first 18 H₂ in Li₆&B₄₀(3) possess an AE of 0.11-0.18 eV, corresponding to a gravimetric density of 7.1 wt%. The eight triangular B₆ corners are shown as well to be good sites for Li-decoration and H₂ adsorption. In a desirable case of Li₁₄&B₄₀-42 H₂(8), a total of 42 H₂ molecules are adsorbed with an AE of 0.32 eV/H₂ for the first 14 H₂ and 0.12 eV/H₂ for the third 14 H₂. A maximum gravimetric density of 13.8 wt% is achieved in 8. The Li-B₄₀-nH₂ system differs markedly from the previous Li-C₆₀-nH₂ and Ti-B₄₀-nH₂ complexes.

Comparative study on the spectral properties of boron clusters Bn(0/-1)(n = 38-40)

The all-boron fullerenes B40(-1) and B39(-1) discovered in recent experiments are characterized and revealed using photoelectron spectroscopy. Except for the photoelectron spectroscopy, one may identify such boron clusters with other spectroscopic techniques, such as infrared spectra and Raman spectra. Insight into the spectral properties of boron clusters is important to understand the boron clusters and find their potential applications. In this work, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations are carried out to comparatively study the vibrational frequencies, infrared spectra, Raman spectra and electronic absorption spectra of boron clusters Bn(0/-1)(n = 38-40). The numerical simulations show that such boron clusters have different and meaningful spectral features. These spectral features are readily compared with future spectroscopy measurements and can be used as fingerprints to distinguish the boron clusters Bn(0/-1) with different structures (cage structure or quasi-planar structure) and with different sizes (n = 38-40).

Endohedral charge-transfer complex Ca@B37−: stabilization of a B373−borospherene trianion by metal-encapsulation

First-principles theory investigations present the possibility of an endohedralC_sCa@B₃₇⁻which contains a 3D aromatic fullerene-likeC_sB₃₇³⁻trianion composed of interwoven double chains.

Concentric dual π aromaticity in bowl-like B30cluster: an all-boron analogue of corannulene

The bowl-like B₃₀cluster is an all-boron analogue of corannulene, featuring concentric dual π aromaticity with 6π and 14π electrons for the inner and the outer boron ribbons, respectively.

Planar B3S2H3−and B3S2H3clusters with a five-membered B3S2ring: boron–sulfur hydride analogues of cyclopentadiene

Boron–sulfur hydride clusters,C_2vB₃S₂H₃⁻and B₃S₂H₃, possess a five-membered B₃S₂ring as the core, which is analogous to cyclopentadiene in terms of π bonding.

Endohedral Ca@B38: stabilization of a B382−borospherene dianion by metal encapsulation

We present the viability of an endohedralC_sCa@B₃₈which contains aC_sB₃₈²⁻borospherene cage composed of interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the B_n^q(q=n− 40) borospherene family fromn= 39–42 ton= 38.

Saturn-like charge-transfer complexes Li4&B36, Li5&B36+, and Li6&B362+: exohedral metalloborospherenes with a perfect cage-like B364−core

We present a first-principles theory prediction of the Saturn-like Li₄&B₃₆, Li₅&B₃₆⁺, and Li₆&B₃₆²⁺which extend the B_n^q(q=n− 40) borospherene family fromn= 38–42 ton= 36.

Aromatic cages B0/+42: unprecedented existence of octagonal holes in boron clusters

The cluster B₄₂⁺exhibits an aromatic cage-like structure containing remarkable octagonal holes.

A new chiral boron cluster B44 containing nonagonal holes

The B44 cluster has a cage-like structure containing two hexagonal, two heptagonal and two nonagonal holes. The presence of nonagonal holes is a new and remarkable finding since they have never been reported before in clusters. The present work does not only identify the new chiral members, but also provide more insight into the growth motif of large-sized boron clusters.

Endohedral C3Ca@B39+and C2Ca@B39+: axially chiral metalloborospherenes based on B39−

Axially chiral endohedral metalloborospherenesC₃/C₂Ca@B₃₉⁺predictedviafirst-principles calculations are charge-transfer complexes in nature with the universal bonding pattern of σ plus π double delocalization.

Boronyl as a terminal ligand in boron oxide clusters: hexagonal ring C2vB6O4and ethylene-like D2hB6O4−/2−

Planar boron boronyl B₆O₄^0/−/2−clusters are predicted. B₆O₄is an inorganic analogue of benzene, whereas B₆O₄^−/2−are ethylene-like with open structures.

Quantum theory of concerted electronic and nuclear fluxes associated with adiabatic intramolecular processes

Example of concerted electronic (right) and nuclear (left) fluxes: isomerization of B₄.

On the structure and bonding in the B4O4+cluster: a boron oxide analogue of the 3,5-dehydrophenyl cation with p and s double aromaticity

The B₄O₄⁺cluster has a hexagonal structure with a boroxol ring. It features double (p and s) aromaticity, akin to the 3,5-dehydrophenyl cation.