Boron Teetotum: Metallic [Ti(B6C xN y)] q and Bimetallic [Ti2(B6C xN y)] q Nine-Membered Heterocycles with x + y = 3 and -1 ≤ q ≤ 3

We investigated the geometry, stability, and aromaticity of a series of singly and doubly titanium-doped boron clusters. Ti dopants bring in planar cyclic form with a nine-membered boron ring B₉^- and B₉^3- and C and N isoelectronic derivatives where perfectly planar B₆N₃, B₆CN₂, B₆C₂N, and B₆C₃ heterorings are coordinated with one and two Ti atoms. The presence of both C and N atoms induces bimetallic heterocycles while Ti₂B₉^q clusters are not stable in cyclic form. Doubly Ti doped clusters have the shape of a teetotum toy. High thermodynamic stability of these bimetallic boron heterocycles, that are global equilibrium structures of corresponding systems, can be understood as the result of a stabilizing overlap between bonding and antibonding MOs of Ti₂ with different eigenstates of B₆C _xN _y cycles. Both C and N elements, which are more electronegative than the B atom, also enjoy the formation of planar nine-membered ring via classical 2c-2e bonding, rather than occupancy of high coordination position. A double aromaticity feature which comprises both σ and π aromaticity is supported by magnetic responses of electron density within a planar cycle. Such an aromatic character is also in line with the classical electron count for both sets of delocalized σ and π electron systems.

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.

Formation of a bi-rhodium boron tube Rh2B18 and its great CO2 capture ability

The geometries, bonding and abilities for CO₂ capture of the doubly rhodium-doped boron cluster Rh₂B₁₈ are presented.

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.

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.

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.

Aromatic character of planar boron-based clusters revisited by ring current calculations

The planarity of small boron-based clusters is the result of an interplay between geometry, electron delocalization, covalent bonding and stability.

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.