•Bn− monoanions have been systematically investigated up to n = 30. However, B26− has remained elusive in this size range.•Here we present a joint photoelectron spectroscopy and first-principles study on the structures and bonding of this seemingly enigmatic cluster.•Extensive global minimum searches and high-level calculations reveal that isomer I dominates the experimental spectrum and represents the smallest 2D boron cluster with a hexagonal vacancy.•Isomer III is found to contribute to the measured PE spectrum as a minor species.•Chemical bonding analyses show that isomer I can be viewed as an all-boron analog of the polycyclic aromatic hydrocarbon C17H11+.Anionic boron clusters have been systematically investigated both experimentally and theoretically up to 30 atoms and have all been proved to be planar or quasi-planar (2D) in their global minima. However, the B26− cluster has remained elusive in this size range up to now, because of its complicated potential landscape. Here we present a joint photoelectron spectroscopy (PES) and first-principles study on the structures and bonding of this seemingly enigmatic cluster. Extensive global minimum searches, followed by high-level calculations and Gibbs free energy corrections, reveal that at least three 2D isomers, I (C1, 2A), II (C1, 2A), and III (C1, 2A), could contribute to the observed PE spectrum for the B26− cluster. Isomer I, which has the lowest free energy at finite temperatures, is found to dominate the experimental spectrum and represents the smallest 2D boron cluster with a hexagonal vacancy. Distinct spectral features are observed for isomer III, which has a pentagonal hole and is found to contribute to the measured PE spectrum as a minor species. Isomer II with a close-packed triangular 2D structure, which is the global minimum at 0 K, may also contribute to the observed spectrum as a minor species. Chemical bonding analyses show that the principal isomer I can be viewed as an all-boron analog of the polycyclic aromatic hydrocarbon C17H11+ in terms of the π bonds.Download high-res image (134KB)Download full-size image

Inspired by the recent discovery of the metal-centered tubular molecular rotor Cs B2-Ta@B18− with the record coordination number of CN = 20 and based on extensive first-principles theory calculations, we present herein the possibility of the largest tubular molecular rotors Cs B3-Ta@B18 (1) and C3v B4-Ta@B18+ (2) and smallest axially chiral endohedral metalloborospherenes D2 Ta@B22− (3 and 3′), unveiling a tubular-to-cage-like structural transition in metal-centered boron clusters at Ta@B22−via effective spherical coordination interactions. The highly stable Ta@B22− (3) as an elegant superatom, which features two equivalent corner-sharing B10 boron double chains interconnected by two B2 units with four equivalent B7 heptagons evenly distributed on the cage surface, conforms to the 18-electron configuration with a bonding pattern of σ + π double delocalization and follows the 2(n + 1)2 electron counting rule for spherical aromaticity (n = 2). Its calculated adiabatic detachment energy of ADE = 3.88 eV represents the electron affinity of the cage-like neutral D2 Ta@B22 which can be viewed as a superhalogen. The infrared, Raman, VCD, and UV-vis spectra of the concerned species are computationally simulated to facilitate their spectral characterizations.

The recently observed cage-like borospherenes D2d B40−/0 and C3/C2 B39− have attracted considerable attention in chemistry and materials science. Based on extensive global minimum searches and first-principles theory calculations, we present herein the possibility of cage-like Cs B39+ (1) and Cs B39+ (2) which possess five hexagonal and heptagonal faces and one filled hexagon and follow the bonding pattern of σ + π double delocalization with 12 delocalized π bonds over a σ-skeleton, adding two new members to the borospherene family. IR, Raman, and UV-vis spectra of Cs B39+ (1) and Cs B39+ (2) are computationally simulated to facilitate their experimental characterization.

We present an extensive density-functional and wave function theory study of partially fluorinated B12Fn0/− (n = 1–6) series, which show that the global minima of B12Fn0/− (n = 2–6) are characterized to encompass a central boron double chain (BDC) nanoribbon and form stable BF2 groups at the corresponding BDC corner when n ≥ 3, but the B12F0/− system maintains the structural feature of the well-known quasi-planar C3v B12. When we put the spotlight on B12F60/− species, our single-point CCSD(T) results unveil that albeit with the 3D icosahedral isomers not being their global minima, C2 B12F6 (6.1, 1A) and C1 B12F6− (12.1, 2A) as typical low-lying isomers are 0.60 and 1.95 eV more stable than their 2D planar counterparts D3h B12F6 (6.7, 1A′) and C2v B12F6− (12.7, 2A2), respectively, alike to B12H60/− species in our previous work. Detailed bonding analyses suggest that B12Fn0/− (n = 2–5) possess ribbon aromaticity with σ plus π double conjugation along the BDC nanoribbon on account of their total number of σ and π delocalized electrons conforming the common electron configuration (π2(n+1)σ2n). Furthermore, the simulated PES spectra of the global minima of B12Fn− (n = 1–6) monoanions may facilitate their experimental characterization in the foreseeable future. Our work provides new examples for ribbon aromaticity and powerful support for the F/H/Au/BO analogy.

Planar boron clusters B11−, B13+, B15+, and B19− have been introduced recently as molecular Wankel motors or tank treads. Here we present a universal mechanism for these dynamically fluxional clusters; that is, they are molecular rotors with inner wheels that rotate almost freely in pseudo-rotating outer bearings, analogous to rotating molecules trapped in pseudo-rotating cages. This mechanism has significant quantum mechanical consequences: the global-minimum structures of the clusters have C2v symmetry, whereas the wheels rotating in pseudo-rotating bearings generate rosette-type shapes with D9h, D10h, D11h, and D13h symmetries. The related rotational/pseudo-rotational energies appear with characteristic band structures, effecting the dynamics.

Boron clusters have been found to exhibit a variety of interesting electronic, structural, and bonding properties. Of particular interest are the recent discoveries of the 2D hexagonal B36−/0 which led to the concept of borophenes and the 3D fullerene-like B40−/0 which marked the onset of borospherene chemistry. Here, we present a joint photoelectron spectroscopic and first-principles study of B37− and B38−, which are in the transition size range between the 2D borophene-type clusters and the 3D borospherenes. These two clusters are found to possess highly stable 2D global-minimum structures consisting of a double-hexagonal vacancy. Detailed bonding analyses reveal that both B37− and B38− are all-boron analogues of coronene (C24H12) with a unique delocalized π system, featuring dual π aromaticity. These clusters with double hexagonal vacancies can be viewed as molecular motifs for the χ3-borophene which is the most stable form of borophenes recently synthesized on an Ag(111) substrate.

Low-dimensional materials (LDMs) involving planar hypercoordinate carbon bonding were predicted to have applications in electronic devices, energy materials, and optical materials, etc. The majority of carbon atoms in such LDMs adopt a tetracoordinate structure, while examples with a higher coordination number are extremely rare and the bonding geometries of those carbons are not perfectly planar. In this work, we designed ribbon-like clusters CnBe3n+2H2n+22+ with planar pentacoordinate carbons (ppCs) and extended the corresponding structural model under 1D periodic boundary conditions (PBCs), leading to a zigzag double-chain C–Be nanoribbon. The beryllium atoms in such a nanoribbon arrange in a cosine shape around the perfect ppCs, which are unprecedented in LDMs. Detailed analyses revealed that the perfect ppC structure in the nanoribbon was geometrically achieved by opening a Be–Be edge of small Be5 rings, thereby making the intra-ring space adjustable to fit the size of the carbons. Electronically, the structure is stabilized by a favourable sandwich type charge distribution and satisfaction of the octet rule for ppCs. Note that all the valence electrons in the nanoribbon are locally delocalized within each ppC moiety, representing a new type of ribbon aromaticity, which should be useful in nanoelectronics. The nanoribbon and its cluster precursor C2Be8H62+ are thermodynamically stable, and are promising targets for experimental realization. The nanoribbon was predicted to be an indirect band gap semiconductor; thus it has potential applications in designing light-weight electronic devices.

A tubular molecular rotor B2-Ta@B18− (1) and boron drum Ta@B20− (2) with the highest coordination number of twenty in chemistry are observed via a joint photoelectron spectroscopy and first-principles theory investigation.

We performed a first-principles study on Fe-, Co-, and Ni-terminated zigzag phosphorene nanoribbons (ZPNRs) with different widths. Magnetic edges were observed for Fe- and Co-terminated ZPNRs, whereas Ni-terminated ZPNRs were nonmagnetic. Interestingly, magnetism could be induced in Ni-ZPNRs by external electric fields, and the distribution of the magnetic moments could be tuned by the direction of the electric fields. Furthermore, Fe-ZPNRs and Co-ZPNRs exhibit semi-metallic and metallic characteristics, respectively, whereas Ni-ZPNRs are mainly semiconductors with band gaps generally increasing monotonously with the increase in nanoribbon width. These fascinating properties of iron-group atom terminated ZPNRs indicate their great potential applications in future spintronics, optoelectronics, and information technologies.

We propose a novel stable borophene (referred to as H-borophene) by tiling seven-membered rings side by side, which is a novel construction pattern never reported in boron sheets or other sheets. It is able to serve as the common precursor of borospherenes (e.g., B39−, B40, B41+, and B422+). Interestingly, a Dirac point appeared at about 0.33 eV below the Fermi level. We found that nanotubes formed by rolling up H-borophene had a great advantage over other boron nanotubes in the case of high curvature, which accounted for the reason why heptagons were preferred in borospherenes. Our study not only proposes a common precursor of borospherenes, but also expands the construction patterns of monolayer sheets.

Based on extensive global searches and first-principles theory calculations, we present herein the possibility of double-ring tubular (B2O2)n clusters (n = 6–42) (2–10) rolled up from the most stable one-dimensional (1D) BO double-chain ribbon (1) in boron monoxides. Tubular (3D) (B2O2)n clusters (n ≥ 6) are found to be systematically much more stable than their previously proposed planar (2D) counterparts, with a 2D–3D structural transition at B12O12 (2). Detailed bonding analyses on 3D (B2O2)n clusters (2–10) and their precursor 1D BO double-chain ribbon (1) reveal two delocalized B–O–B 3c-2e π bonds over each edge-sharing B4O2 hexagonal unit which form a unique 6c-4e o-bond to help stabilize the systems. The IR, Raman, UV-vis, and photoelectron spectra of the concerned species are computationally simulated to facilitate their experimental characterization.

BN co-doped β-graphyne (β-GY) was investigated using state-of-the-art theoretical calculations. β-GY with sp or sp2 carbon pairs substituted by BN pairs was referred to as β-GYBN1 or β-GYBN2, respectively. Their dynamic and thermal stabilities were confirmed by phonon spectrum calculations and ab initio molecular dynamics (AIMD) simulations. Interestingly, the ternary hybrid BCN monolayer β-GYBN1 was predicted to be semimetallic with multiple distorted Dirac cones at the Fermi level, including crossed ones and gapped ones. Their infrared (IR) and Raman spectra were simulated to serve as fingerprints for experimental identification. It was also found that hydrogen atom adsorption would depress the energy bands of β-GYBN1, and made other isotropic Dirac cones crossed at the Fermi level. Our study not only indicates the potential applications of BN co-doped β-GY in future spintronics and optoelectronics, but also implies a possible approach to explore novel semimetallic Dirac materials.

Based on extensive first-principles theory calculations, we present the possibility of construction of the Saturn-like charge-transfer complexes Li4&B36 (2), Li5&B36+ (3), and Li6&B362+ (4) all of which contain a perfect cage-like B364− (1) core composed of twelve interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq borospherene family from n = 38–42 to n = 36 with the highest symmetry of Th.

A planar, elongated B15+ cationic cluster is shown to be structurally fluxional and functions as a nanoscale tank tread on the basis of electronic structure calculations, bonding analyses, and molecular dynamics simulations. The outer B11 peripheral ring behaves like a flexible chain gliding around an inner B4 rhombus core, almost freely at the temperature of 500 K. The rotational energy barrier is only 1.37 kcal mol−1 (0.06 eV) at the PBE0/6-311+G* level, further refined to 1.66 kcal mol−1 (0.07 eV) at the single-point CCSD(T)/6-311G*//CCSD/6-311G* level. Two soft vibrational modes of 166.3 and 258.3 cm−1 are associated with the rotation, serving as double engines for the system. Bonding analysis suggests that the “island” electron clouds, both σ and π, between the peripheral ring and inner core flow and shift continuously during the intramolecular rotation, facilitating the dynamic fluxionality of the system with a small rotational barrier. The B15+ cluster, roughly 0.6 nm in dimension, is the first double-axle nanoscale tank tread equipped with two engines, which expands the concepts of molecular wheels, Wankel motors, and molecular tanks.

Based on extensive first-principles theory calculations, we present the possibility of an endohedral charge-transfer complex, Cs Ca@B37− (I), which contains a 3D aromatic fullerene-like Cs B373− (II) trianion composed of interwoven boron double chains with twelve delocalized multicenter π bonds (12 mc–2e π, m = 5, 6) over a σ skeleton, completing the Bnq borospherene family (q = n − 40) in the size range of n = 36–42.

Based on extensive global-minimum searches and first-principles electronic structure calculations, we present the viability of an endohedral metalloborospherene Cs Ca@B38 (1) which contains a Cs B382− (2) dianion composed of interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq (q = n − 40) borospherene family from n = 39–42 to n = 38. Transition metal endohedral complexes Cs M@B38 (M = Sc, Y, Ti) (3, 5, 7) based on Cs B382− (2) are also predicted.

We present a concept that an elongated, planar boron cluster can serve as a “tank tread” at the sub-nanometer scale, a novel propulsion system for potential nanomachines. Density functional calculations at the PBE0/6-311+G* level for the global-minimum B11−C2v (1A1) and B11C2v (2B2) structures along the soft in-plane rotational mode allow the identification of their corresponding B11−C2v and B11C2v transition states, with small rotational energy barriers of 0.42 and 0.55 kcal mol−1, respectively. The energy barriers are refined to 0.35 and 0.60 kcal mol−1 at the single-point CCSD(T) level, suggesting that the clusters are structurally fluxional at room temperature. Molecular dynamics simulations show that B11− and B11 behave exactly like a tank tread, in which the peripheral B9 ring rotates almost freely around the B2 core. A full turn of rotation may be accomplished in around 2 ps. In contrast to molecular wheels or Wankel motors, the peripheral boron atoms in the tank tread behave as a flexible chain gliding around, rather than as a rigid wheel rotation. This finding is beyond imagination, which expands the concepts of molecular wheels and Wankel motors.

Considerable recent research effort has been devoted to the development of boronyl (BO) chemistry. Here we predict three perfectly planar boron boronyl clusters: C2v B6O4 (1, 1A1), D2h B6O4− (2, 2B3u), and D2h B6O42− (3, 1Ag). These are established as the global-minimum structures on the basis of the coalescence kick and basin hopping structural searches and electronic structure calculations at the B3LYP/aug-cc-pVTZ level, with complementary CCSD/6-311+G* and single-point CCSD(T)/6-311+G*//B3LYP/aug-cc-pVTZ calculations for 2. The C2v B6O4 neutral cluster features a hexagonal B4O2 ring with two terminal BO groups. The D2h B6O4−/2− clusters have ethylene-like structures and are readily formulated as B2(BO)4−/2−, in which a B2 core with double bond character is bonded to four terminal BO groups. Chemical bonding analyses show that B6O4 (1) possesses an aromatic π bonding system with three delocalized, six-centered π bonds over the hexagonal ring, rendering it an inorganic analogue of benzene, whereas the B6O4−/2− (2 and 3) species closely resemble ethylene in terms of structures and bonding. This work provides new examples for the analogy between boron oxides and hydrocarbons.

Using the newly discovered borospherenes C3 B39− and C2 B39− as molecular devices and based on extensive global-minimum searches and first-principles calculations, we present herein the possibility of the first axially chiral metalloborospherenes C3 Ca@B39+ (1, 1A) and C2 Ca@B39+ (2, 1A), which are the global minimum and the second lowest-lying isomer of CaB39+, respectively. These metalloborospherene species turn out to be charge-transfer complexes Ca2+@B39− in nature, with the Ca centre on the C3 or C2 molecular axis donating one electron to the B39 cage which behaves like a superhalogen. Molecular orbital analyses indicate that C3/C2 Ca2+@B39− possess the universal bonding pattern of σ plus π double delocalization, similar to their C3/C2 B39− parents. Molecular dynamics simulations show that both C3 Ca@B39+ (1) and C2 Ca@B39+ (2) are dynamically stable at 200 K, with the former starting to fluctuate structurally at 300 K and the latter at 400 K, again similar to C3/C2 B39−. The infrared and Raman spectra of C3/C2 Ca@B39+ (1/2) are simulated and compared with those of C3/C2 B39− to facilitate their forthcoming experimental characterization.

Based upon global searches and electronic structure calculations at the B3LYP and CCSD(T) levels, we present the global-minimum structures of two ternary B–O–H and B–S–H rhombic clusters: D2h B2O2H2 (1, 1Ag) and C2v B2S2H2 (2, 1A1). Both species feature a B2X2 (X = O or S) four-membered ring as the core, with two H atoms attached terminally. The former cluster is perfectly planar, whereas the latter undergoes a slight butterfly distortion. Bonding analyses reveal a four-center four-electron (4c–4e) o-bond in these clusters, which are 4π systems in a nonbonding/bonding combination, in contrast to an antibonding/bonding combination in a classical 4π antiaromatic hydrocarbon such as cyclobutadiene (C4H4). Clusters 1 and 2 are considered to be aromatic. The present results also help elucidate the bonding nature in the relevant heteroatomic ring B2N2H4 system and suggest that it is not appropriate to consider B2N2H4 as an inorganic cyclobutadiene, a conception that has been in existence in the literature for over 40 years. The electronic properties of the global-minimum clusters 1 and 2 are predicted. It is shown that B2O2H2 (1) and B2S2H2 (2) may serve as effective inorganic ligands to form sandwich-type transition metal complexes, such as D2d [B2O2H2]2Ni (3) and D2d [B2S2H2]2Ni (4).

The double-chain boron ribbon should be taken as an element geometric unit for the construction of boron fullerenes and sheets. In this work, a series of B2nC2H2 clusters (n = 2–9) were extensively investigated using the density functional theory and the coupled cluster method. The most stable structures of B2nC2H2 are planar double-chain nanoribbon with lengths from 3.9 to 15.0 Å. The adaptive natural density partitioning analyses show that there exist conjugated multi-center π bonds along the nanoribbons. The two-dimensional contour pictures of the nucleus-independent chemical shifts reveal that B2nC2H2 clusters have ribbon aromaticity that fluctuates along the ribbons. This finding will provide new insights on the boron fullerenes and the two-dimensional boron sheets.

Chirality plays an important role in chemistry, biology, and materials science. The recent discovery of the B40–/0 borospherenes marks the onset of a class of boron-based nanostructures. Here we report the observation of axially chiral borospherene in the B39– nanocluster on the bases of photoelectron spectroscopy, global minimum searches, and electronic structure calculations. Extensive structural searches in combination with density functional and CCSD(T) calculations show that B39– has a C3 cage global minimum with a close-lying C2 cage isomer. Both the C3 and C2 B39– cages are chiral with degenerate enantiomers. The C3 global minimum consists of three hexagons and three heptagons around the vertical C3 axis. The C2 isomer is built on two hexagons on the top and at the bottom of the cage with four heptagons around the waist. Both the C3 and C2 axially chiral isomers of B39– are present in the experiment and contribute to the observed photoelectron spectrum. The chiral borospherenes also exhibit three-dimensional aromaticity, featuring σ and π double delocalization for all valence electrons. Molecular dynamics simulations reveal that these chiral B39– cages are structurally fluxional above room temperature, compared to the highly robust D2d B40 borospherene. The current findings add chiral members to the borospherene family and indicate the structural diversity of boron-based nanomaterials.Keywords: all-boron fullerene; axial chirality; borospherene; global minimum searches; photoelectron spectroscopy; σ and π double delocalization;

Elemental boron is electron-deficient and cannot form graphene-like structures. Instead, triangular boron lattices with hexagonal vacancies have been predicted to be stable. A recent experimental and computational study showed that the B36 cluster has a planar C6v structure with a central hexagonal hole, providing the first experimental evidence for the viability of atom-thin boron sheets with hexagonal vacancies, dubbed borophene. Here we report a boron cluster with a double-hexagonal vacancy as a new and more flexible structural motif for borophene. Photoelectron spectrum of B35– displays a simple pattern with certain similarity to that of B36–. Global minimum searches find that both B35– and B35 possess planar hexagonal structures, similar to that of B36, except a missing interior B atom that creates a double-hexagonal vacancy. The closed-shell B35– is found to exhibit triple π aromaticity with 11 delocalized π bonds, analogous to benzo(g,h,i)perylene (C22H12). The B35 cluster can be used to build atom-thin boron sheets with various hexagonal hole densities, providing further experimental evidence for the viability of borophene.

Flat boron has recently emerged as a fascinating concept in cluster science. Here we present computational evidence for the quasi-planar all-boron aromatic B36 (C6v, 1A1) and B36− (C2v, 2A1) clusters, established as the global-minimum structures on the basis of Stochastic Surface Walking (SSW) searches. The energetics for low-lying isomeric structures are evaluated using the validated density-functional method at the PBE0/6-311+G* level. Our global-minimum structures are in line with a recent report (Z. A. Piazza et al., Nat. Commun., 2014, 5, 3113). These structures consist of two-dimensional close-packing boron with a perfect hexagonal hole at the center, which may serve as molecular models for the monolayer boron α sheet. Chemical bonding analysis indicates that B36 and B36− are all-boron analogues of coronene (C24H12), featuring concentric dual π aromaticity with an inner π sextet and an outer π sextet. The hydrogenated B36H6 (C6v, 1A1) model cluster shows similar bonding properties, which possesses concentric triple aromaticity with inner π, outer π, and outer σ sextets.

We explore the structural and bonding properties of the electron-deficient boron oxide clusters, using a series of B3On−/0/+ (n = 2–4) clusters as examples. Global-minimum structures of these boron oxide clusters are identified via unbiased Coalescence Kick and Basin Hopping searches, which show a remarkable size and charge-state dependence. An array of new bonding elements are revealed: core boronyl groups, dual 3c–4e hypervalent bonds (ω-bonds), and rhombic 4c–4e bonds (o-bonds). In favorable cases, oxygen can exhaust all its 2s/2p electrons to facilitate the formation of B–O bonds. The current findings should help understand the bonding nature of low-dimensional boron oxide nanomaterials and bulk boron oxides.

We report on the structural and electronic properties and chemical bonding in a series of lithium and gold alloyed boron oxide clusters: B2O3−, LiB2O3−, AuB2O3−, and LiAuB2O3−. The clusters have been produced by laser vaporization and characterized using photoelectron spectroscopy, in combination with the Coalescence Kick and Basin Hopping global-minimum searches and density-functional theory and molecular orbital theory calculations. Electron affinities of B2O3, LiB2O3, AuB2O3, and LiAuB2O3 neutral clusters are measured to be 1.45 ± 0.08, 4.25 ± 0.08, 6.05 ± 0.08, and 2.40 ± 0.08 eV, respectively. The experimental and computational data allow the cluster structures to be established for the anions as well as their neutrals. While B2O3− (C2v) is bent, the three alloy clusters, LiB2O3− (C∞v), AuB2O3− (Cs), and LiAuB2O3− (C∞v), adopt linear or quasi-linear geometries with a metal center inserted between BO and OBO subunits, featuring charge transfer complexes, covalent gold, hyperhalogen, and dual three-center four-electron (3c-4e) π hyperbonds. The current results suggest the possibility of altering and fine-tuning the properties of boron oxides via alloying, which may lead to markedly different electronic structures and chemical reactivities. The LiB2O3 cluster belongs to the class of oxidizing agents called superhalogens, whereas AuB2O3 is a hyperhalogen species. Dual 3c-4e π hyperbonds represent a critical bonding element in boron oxides and are considered to be the root of delocalized bonding and aromaticity therein.

Because of the biological importance of thiols, the development of probes for thiols has been an active research area in recent years. In this review, we summarize the results of recent exciting reports regarding thiol-addition reactions and their applications in thiol recognition. The examples reported can be classified into four reaction types including 1,1, 1,2, 1,3, 1,4 addition reactions, according to their addition mechanisms, based on different Michael acceptors. In all cases, the reactions are coupled to color and/or emission changes, although some examples dealing with electrochemical recognition have also been included. The use of thiol-addition reactions is a very simple and straightforward procedure for the preparation of thiol-sensing probes.

We report an extensive density-functional theory and coupled-cluster CCSD(T) study on boron dihydride dianion clusters BnH22− (n = 6–22) and their dilithiated Li2BnH20/− salt complexes. Double-chain (DC) planar nanoribbon structures are confirmed as the global minima for the BnH22− (n = 6–22) clusters. Charging proves to be an effective mechanism to stabilize and extend the DC planar nanostructures, capable of producing elongated boron nanoribbons with variable lengths between 4.3–17.0 Å. For the dilithiated salts, the DC planar nanoribbons are lowest in energy up to Li2B14H2 and represent true minima for all Li2BnH20/− (n = 6–22) species. These boron nanostructures may be viewed as molecular zippers, in which two atomically-thin molecular wires are zipped together via delocalized bonds. Bonding analysis reveals the nature of π plus σ double conjugation in the lithiated DC nanoribbon Li2BnH20/− (n up to 22) model clusters, which exhibit a 4n pattern in adiabatic detachment energies, ionization potentials, and second-order differences in total energies. Band structure analysis of the infinite DC boron nanoribbon structure also reveals that both π and σ electrons participate in electric conduction, much different from the monolayer boron α-sheet in which only π electrons act as carriers. A concept of “ribbon aromaticity” is proposed for this quasi-one-dimensional system, where regular π versus σ alternation of the delocalized electron clouds along the nanoribbons results in enhanced stability for a series of “magic” nanoribbon clusters. The total number of delocalized π and σ electrons for ribbon aromaticity collectively conforms to the (4n + 2) Hückel rule. Ribbon aromaticity appears to be a general concept in other nanoribbon systems as well.

We report a photoelectron spectroscopy and density-functional theory study of the B12Au− and B13O− clusters and their neutrals, which are shown to be six π electron aromatic compounds between the quasi-planar all-boron B12 benzene-analogue and a monovalent Au or BO ligand. Electron affinities of B12Au and B13O are measured to be 3.48 ± 0.04 and 3.90 ± 0.04 eV, respectively. Structural searches are performed for B12Au− and B13O−, which are compared with the isovalent B12H− cluster. The global minima of B12Au− and B13O− both feature an almost intact B12 cluster with the Au and BO ligands bonded to its periphery, respectively. For B12Au−, a low-lying isomer is also identified, which is only 0.4 kcal mol−1 above the global minimum, in agreement with the experimental observation of a weakly populated isomer in the cluster beam of B12Au−. These aromatic compound clusters provide new examples for the Au/H isolobal analogy and the boronyl (BO) chemistry.

Using the first-principle approaches, we predict a B6(BO)7– cluster with a face-capping μ3-BO, which is the boron oxide analogue of closo-B6H7– with a face-capping μ3-H. Detailed topological analysis of electron density clearly reveals the existence of three rhombic 4c–2e bonds around the B/H apex in both C3v B6(BO)7– and C3v B6H7–, which possesses similar electron densities at their bond and ring critical points. The adaptive natural density partitioning (AdNDP) analysis provides a direct and visual picture of the B–B–B–B/H 4c–2e bonds for the first time. Adiabatic and vertical electron detachment energies of the concerned monoanions are calculated to facilitate their future photoelectron spectroscopy measurements and characterizations. The presence of the B6(BO)7– and B6H7– clusters extends the BO/H isolobal analogy to the whole μn-BO/H series (n = 1, 2, and 3) and enriches the chemistry of boronyl.

The most stable mono-layer boron sheets were predicted to have both the isolated hexagonal hole and the twin-hexagonal hole. Previous investigations indicate that planar B18Hnq (n = 3–6, q = n − 4) are the building blocks of boron sheets with isolated hexagonal holes. Extensive DFT investigations performed in this work show that D2h B26H8, D2h B26H82+, and C2 B26H6, may serve as the building blocks of boron sheets with twin-hexagonal holes. These bicyclic clusters possess planar or quasi-planar geometries at B3LYP/6-311+G(d,p) level, with 16, 14, and 14 delocalized π electrons, respectively. Detailed analyses indicate that they are overall aromatic in nature, with the formation of islands of both σ and π aromaticity. They are analogous to D2h C16H14 and D2h C16H142+ in π bonding patterns, respectively, but fundamentally different from the latter in σ-bonding. Remarkably, all of them appear to be energetically the lowest-lying isomers obtained, which are promising targets for future gas phase syntheses. These hydroboron clusters, together with B18Hnq clusters, establish the molecular basis for modeling the short-range structures, nucleation, and growth processes of monolayer boron sheets. The results obtained in this work enrich the chemistry of boron hydride clusters and expand the analogy relationship between hydroborons and hydrocarbons.

Based upon comprehensive theoretical investigations and known experimental observations, we predict the existence of the double-chain planar D2h B4H2(1), C2h B8H2(3), and C2h B12H2(5) which appear to be the lowest-lying isomers of the systems at the density functional theory level. These conjugated aromatic borenes turn out to be the boron hydride analogues of the conjugated ethylene D2h C2H4(2), 1,3-butadiene C2h C4H6(4), and 1,3,5-hexatriene C2h C6H8(6), respectively, indicating that a B4 rhombus in B2nH2 borenes (n = 2, 4, 6) is equivalent to a CC double bond unit in the corresponding CnHn+2 hydrocarbons. Detailed canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), and electron localization function (ELF) analyses unravel the bonding patterns of these novel borene clusters and indicate that they are all overall aromatic in nature with the formation of islands of both σ- and π- aromaticity. The double-chain planar or quasi-planar C2v B3H2−(7), C2 B5H2−(8), and C2h B6H2(9) with one delocalized π orbital, C2v B7H2−(10), C2 B9H2−(11), and C2h B10H2(12) with two delocalized π orbitals, and C2v B11H2−(13) with three delocalized π orbitals are found to be analogous in π-bonding to D2h B4H2(1), C2h B8H2(3), and C2h B12H2(5), respectively. We also calculated the electron affinities and ionization potentials of the neutrals and simulated the photoelectron spectroscopic spectra of the monoanions to facilitate their future experimental characterization. The results obtained in this work enrich the analogous relationship between hydroborons and their hydrocarbon counterparts and help to understand the high stability of the theoretically predicted all-boron nanostructures which favor the formation of double-chain substructures.

Despite a seemingly simple appearance, cyclobutanetetraone (C4O4) has four low-lying electronic states. Determining the energetic ordering of these states and the ground state of C4O4– theoretically has been proven to be considerably challenging and remains largely unresolved to date. Here, we report a low-temperature negative ion photoelectron spectroscopic approach. Well-resolved spectra were obtained at both 193 and 266 nm. Combined with recent theoretical studies and our own Franck–Condon factors simulations, the ground state of C4O4– and the ground and two low-lying excited states of C4O4 are determined to be 2A2u, 3B2u, 1A1g (8π), and 1B2u, respectively. The frequency of the ring breathing mode (1810 ± 20 cm–1), the electron affinity (3.475 ± 0.005 eV), and the term values of 1A1g (8π) (6.27 ± 0.5 kJ/mol) and 1B2u (13.50 ± 0.5 kJ/mol) are also directly obtained from the experiments.Keywords: diradical species; electronic structures of C4O4 and C4O4−; negative ion photoelectron spectroscopy;

The BO groups also dominate the structures and bonding of boron oxide clusters and boron boronyl complexes, in which BO groups occupy terminal, bridging, or face-capping positions. The bridging η2-BO groups feature three-center two-electron bonds, akin to the BHB τ bonds in boranes. A close isolobal analogy is thus established between boron oxide clusters and boranes, offering vast opportunities for the rational design of novel boron oxide clusters and compounds. Boron boronyl clusters may also serve as molecular models for mechanistic understanding of the combustion of boron and boranes. An effort to tune the B versus O composition in boron oxide clusters leads to the discovery of boronyl boroxine, D3h B3O3(BO)3, an analogue of boroxine and borazine and a new member of the “inorganic benzene” family. Furthermore, a unique concept of π and σ double conjugation is proposed for the first time to elucidate the structures and bonding in the double-chain nanoribbon boron diboronyl clusters, which appear to be inorganic analogues of polyenes, cumulenes, and polyynes. This Account concludes with a brief outlook for the future directions in this emerging and expanding research field.

Using the newly discovered borospherenes C3 B39− and C2 B39− as molecular devices and based on extensive global-minimum searches and first-principles calculations, we present herein the possibility of the first axially chiral metalloborospherenes C3 Ca@B39+ (1, 1A) and C2 Ca@B39+ (2, 1A), which are the global minimum and the second lowest-lying isomer of CaB39+, respectively. These metalloborospherene species turn out to be charge-transfer complexes Ca2+@B39− in nature, with the Ca centre on the C3 or C2 molecular axis donating one electron to the B39 cage which behaves like a superhalogen. Molecular orbital analyses indicate that C3/C2 Ca2+@B39− possess the universal bonding pattern of σ plus π double delocalization, similar to their C3/C2 B39− parents. Molecular dynamics simulations show that both C3 Ca@B39+ (1) and C2 Ca@B39+ (2) are dynamically stable at 200 K, with the former starting to fluctuate structurally at 300 K and the latter at 400 K, again similar to C3/C2 B39−. The infrared and Raman spectra of C3/C2 Ca@B39+ (1/2) are simulated and compared with those of C3/C2 B39− to facilitate their forthcoming experimental characterization.

Considerable recent research effort has been devoted to the development of boronyl (BO) chemistry. Here we predict three perfectly planar boron boronyl clusters: C2v B6O4 (1, 1A1), D2h B6O4− (2, 2B3u), and D2h B6O42− (3, 1Ag). These are established as the global-minimum structures on the basis of the coalescence kick and basin hopping structural searches and electronic structure calculations at the B3LYP/aug-cc-pVTZ level, with complementary CCSD/6-311+G* and single-point CCSD(T)/6-311+G*//B3LYP/aug-cc-pVTZ calculations for 2. The C2v B6O4 neutral cluster features a hexagonal B4O2 ring with two terminal BO groups. The D2h B6O4−/2− clusters have ethylene-like structures and are readily formulated as B2(BO)4−/2−, in which a B2 core with double bond character is bonded to four terminal BO groups. Chemical bonding analyses show that B6O4 (1) possesses an aromatic π bonding system with three delocalized, six-centered π bonds over the hexagonal ring, rendering it an inorganic analogue of benzene, whereas the B6O4−/2− (2 and 3) species closely resemble ethylene in terms of structures and bonding. This work provides new examples for the analogy between boron oxides and hydrocarbons.

A planar, elongated B15+ cationic cluster is shown to be structurally fluxional and functions as a nanoscale tank tread on the basis of electronic structure calculations, bonding analyses, and molecular dynamics simulations. The outer B11 peripheral ring behaves like a flexible chain gliding around an inner B4 rhombus core, almost freely at the temperature of 500 K. The rotational energy barrier is only 1.37 kcal mol−1 (0.06 eV) at the PBE0/6-311+G* level, further refined to 1.66 kcal mol−1 (0.07 eV) at the single-point CCSD(T)/6-311G*//CCSD/6-311G* level. Two soft vibrational modes of 166.3 and 258.3 cm−1 are associated with the rotation, serving as double engines for the system. Bonding analysis suggests that the “island” electron clouds, both σ and π, between the peripheral ring and inner core flow and shift continuously during the intramolecular rotation, facilitating the dynamic fluxionality of the system with a small rotational barrier. The B15+ cluster, roughly 0.6 nm in dimension, is the first double-axle nanoscale tank tread equipped with two engines, which expands the concepts of molecular wheels, Wankel motors, and molecular tanks.

We propose a novel stable borophene (referred to as H-borophene) by tiling seven-membered rings side by side, which is a novel construction pattern never reported in boron sheets or other sheets. It is able to serve as the common precursor of borospherenes (e.g., B39−, B40, B41+, and B422+). Interestingly, a Dirac point appeared at about 0.33 eV below the Fermi level. We found that nanotubes formed by rolling up H-borophene had a great advantage over other boron nanotubes in the case of high curvature, which accounted for the reason why heptagons were preferred in borospherenes. Our study not only proposes a common precursor of borospherenes, but also expands the construction patterns of monolayer sheets.

Based on extensive first-principles theory calculations, we present the possibility of construction of the Saturn-like charge-transfer complexes Li4&B36 (2), Li5&B36+ (3), and Li6&B362+ (4) all of which contain a perfect cage-like B364− (1) core composed of twelve interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq borospherene family from n = 38–42 to n = 36 with the highest symmetry of Th.

We report a photoelectron spectroscopy and density-functional theory study of the B12Au− and B13O− clusters and their neutrals, which are shown to be six π electron aromatic compounds between the quasi-planar all-boron B12 benzene-analogue and a monovalent Au or BO ligand. Electron affinities of B12Au and B13O are measured to be 3.48 ± 0.04 and 3.90 ± 0.04 eV, respectively. Structural searches are performed for B12Au− and B13O−, which are compared with the isovalent B12H− cluster. The global minima of B12Au− and B13O− both feature an almost intact B12 cluster with the Au and BO ligands bonded to its periphery, respectively. For B12Au−, a low-lying isomer is also identified, which is only 0.4 kcal mol−1 above the global minimum, in agreement with the experimental observation of a weakly populated isomer in the cluster beam of B12Au−. These aromatic compound clusters provide new examples for the Au/H isolobal analogy and the boronyl (BO) chemistry.

Based upon comprehensive theoretical investigations and known experimental observations, we predict the existence of the double-chain planar D2h B4H2(1), C2h B8H2(3), and C2h B12H2(5) which appear to be the lowest-lying isomers of the systems at the density functional theory level. These conjugated aromatic borenes turn out to be the boron hydride analogues of the conjugated ethylene D2h C2H4(2), 1,3-butadiene C2h C4H6(4), and 1,3,5-hexatriene C2h C6H8(6), respectively, indicating that a B4 rhombus in B2nH2 borenes (n = 2, 4, 6) is equivalent to a CC double bond unit in the corresponding CnHn+2 hydrocarbons. Detailed canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), and electron localization function (ELF) analyses unravel the bonding patterns of these novel borene clusters and indicate that they are all overall aromatic in nature with the formation of islands of both σ- and π- aromaticity. The double-chain planar or quasi-planar C2v B3H2−(7), C2 B5H2−(8), and C2h B6H2(9) with one delocalized π orbital, C2v B7H2−(10), C2 B9H2−(11), and C2h B10H2(12) with two delocalized π orbitals, and C2v B11H2−(13) with three delocalized π orbitals are found to be analogous in π-bonding to D2h B4H2(1), C2h B8H2(3), and C2h B12H2(5), respectively. We also calculated the electron affinities and ionization potentials of the neutrals and simulated the photoelectron spectroscopic spectra of the monoanions to facilitate their future experimental characterization. The results obtained in this work enrich the analogous relationship between hydroborons and their hydrocarbon counterparts and help to understand the high stability of the theoretically predicted all-boron nanostructures which favor the formation of double-chain substructures.

We report an extensive density-functional theory and coupled-cluster CCSD(T) study on boron dihydride dianion clusters BnH22− (n = 6–22) and their dilithiated Li2BnH20/− salt complexes. Double-chain (DC) planar nanoribbon structures are confirmed as the global minima for the BnH22− (n = 6–22) clusters. Charging proves to be an effective mechanism to stabilize and extend the DC planar nanostructures, capable of producing elongated boron nanoribbons with variable lengths between 4.3–17.0 Å. For the dilithiated salts, the DC planar nanoribbons are lowest in energy up to Li2B14H2 and represent true minima for all Li2BnH20/− (n = 6–22) species. These boron nanostructures may be viewed as molecular zippers, in which two atomically-thin molecular wires are zipped together via delocalized bonds. Bonding analysis reveals the nature of π plus σ double conjugation in the lithiated DC nanoribbon Li2BnH20/− (n up to 22) model clusters, which exhibit a 4n pattern in adiabatic detachment energies, ionization potentials, and second-order differences in total energies. Band structure analysis of the infinite DC boron nanoribbon structure also reveals that both π and σ electrons participate in electric conduction, much different from the monolayer boron α-sheet in which only π electrons act as carriers. A concept of “ribbon aromaticity” is proposed for this quasi-one-dimensional system, where regular π versus σ alternation of the delocalized electron clouds along the nanoribbons results in enhanced stability for a series of “magic” nanoribbon clusters. The total number of delocalized π and σ electrons for ribbon aromaticity collectively conforms to the (4n + 2) Hückel rule. Ribbon aromaticity appears to be a general concept in other nanoribbon systems as well.

Flat boron has recently emerged as a fascinating concept in cluster science. Here we present computational evidence for the quasi-planar all-boron aromatic B36 (C6v, 1A1) and B36− (C2v, 2A1) clusters, established as the global-minimum structures on the basis of Stochastic Surface Walking (SSW) searches. The energetics for low-lying isomeric structures are evaluated using the validated density-functional method at the PBE0/6-311+G* level. Our global-minimum structures are in line with a recent report (Z. A. Piazza et al., Nat. Commun., 2014, 5, 3113). These structures consist of two-dimensional close-packing boron with a perfect hexagonal hole at the center, which may serve as molecular models for the monolayer boron α sheet. Chemical bonding analysis indicates that B36 and B36− are all-boron analogues of coronene (C24H12), featuring concentric dual π aromaticity with an inner π sextet and an outer π sextet. The hydrogenated B36H6 (C6v, 1A1) model cluster shows similar bonding properties, which possesses concentric triple aromaticity with inner π, outer π, and outer σ sextets.

We explore the structural and bonding properties of the electron-deficient boron oxide clusters, using a series of B3On−/0/+ (n = 2–4) clusters as examples. Global-minimum structures of these boron oxide clusters are identified via unbiased Coalescence Kick and Basin Hopping searches, which show a remarkable size and charge-state dependence. An array of new bonding elements are revealed: core boronyl groups, dual 3c–4e hypervalent bonds (ω-bonds), and rhombic 4c–4e bonds (o-bonds). In favorable cases, oxygen can exhaust all its 2s/2p electrons to facilitate the formation of B–O bonds. The current findings should help understand the bonding nature of low-dimensional boron oxide nanomaterials and bulk boron oxides.

We report on the structural and electronic properties and chemical bonding in a series of lithium and gold alloyed boron oxide clusters: B2O3−, LiB2O3−, AuB2O3−, and LiAuB2O3−. The clusters have been produced by laser vaporization and characterized using photoelectron spectroscopy, in combination with the Coalescence Kick and Basin Hopping global-minimum searches and density-functional theory and molecular orbital theory calculations. Electron affinities of B2O3, LiB2O3, AuB2O3, and LiAuB2O3 neutral clusters are measured to be 1.45 ± 0.08, 4.25 ± 0.08, 6.05 ± 0.08, and 2.40 ± 0.08 eV, respectively. The experimental and computational data allow the cluster structures to be established for the anions as well as their neutrals. While B2O3− (C2v) is bent, the three alloy clusters, LiB2O3− (C∞v), AuB2O3− (Cs), and LiAuB2O3− (C∞v), adopt linear or quasi-linear geometries with a metal center inserted between BO and OBO subunits, featuring charge transfer complexes, covalent gold, hyperhalogen, and dual three-center four-electron (3c-4e) π hyperbonds. The current results suggest the possibility of altering and fine-tuning the properties of boron oxides via alloying, which may lead to markedly different electronic structures and chemical reactivities. The LiB2O3 cluster belongs to the class of oxidizing agents called superhalogens, whereas AuB2O3 is a hyperhalogen species. Dual 3c-4e π hyperbonds represent a critical bonding element in boron oxides and are considered to be the root of delocalized bonding and aromaticity therein.

Based upon global searches and electronic structure calculations at the B3LYP and CCSD(T) levels, we present the global-minimum structures of two ternary B–O–H and B–S–H rhombic clusters: D2h B2O2H2 (1, 1Ag) and C2v B2S2H2 (2, 1A1). Both species feature a B2X2 (X = O or S) four-membered ring as the core, with two H atoms attached terminally. The former cluster is perfectly planar, whereas the latter undergoes a slight butterfly distortion. Bonding analyses reveal a four-center four-electron (4c–4e) o-bond in these clusters, which are 4π systems in a nonbonding/bonding combination, in contrast to an antibonding/bonding combination in a classical 4π antiaromatic hydrocarbon such as cyclobutadiene (C4H4). Clusters 1 and 2 are considered to be aromatic. The present results also help elucidate the bonding nature in the relevant heteroatomic ring B2N2H4 system and suggest that it is not appropriate to consider B2N2H4 as an inorganic cyclobutadiene, a conception that has been in existence in the literature for over 40 years. The electronic properties of the global-minimum clusters 1 and 2 are predicted. It is shown that B2O2H2 (1) and B2S2H2 (2) may serve as effective inorganic ligands to form sandwich-type transition metal complexes, such as D2d [B2O2H2]2Ni (3) and D2d [B2S2H2]2Ni (4).

Based on extensive first-principles theory calculations, we present the possibility of an endohedral charge-transfer complex, Cs Ca@B37− (I), which contains a 3D aromatic fullerene-like Cs B373− (II) trianion composed of interwoven boron double chains with twelve delocalized multicenter π bonds (12 mc–2e π, m = 5, 6) over a σ skeleton, completing the Bnq borospherene family (q = n − 40) in the size range of n = 36–42.

Based on extensive global-minimum searches and first-principles electronic structure calculations, we present the viability of an endohedral metalloborospherene Cs Ca@B38 (1) which contains a Cs B382− (2) dianion composed of interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq (q = n − 40) borospherene family from n = 39–42 to n = 38. Transition metal endohedral complexes Cs M@B38 (M = Sc, Y, Ti) (3, 5, 7) based on Cs B382− (2) are also predicted.

BN co-doped β-graphyne (β-GY) was investigated using state-of-the-art theoretical calculations. β-GY with sp or sp2 carbon pairs substituted by BN pairs was referred to as β-GYBN1 or β-GYBN2, respectively. Their dynamic and thermal stabilities were confirmed by phonon spectrum calculations and ab initio molecular dynamics (AIMD) simulations. Interestingly, the ternary hybrid BCN monolayer β-GYBN1 was predicted to be semimetallic with multiple distorted Dirac cones at the Fermi level, including crossed ones and gapped ones. Their infrared (IR) and Raman spectra were simulated to serve as fingerprints for experimental identification. It was also found that hydrogen atom adsorption would depress the energy bands of β-GYBN1, and made other isotropic Dirac cones crossed at the Fermi level. Our study not only indicates the potential applications of BN co-doped β-GY in future spintronics and optoelectronics, but also implies a possible approach to explore novel semimetallic Dirac materials.

Because of the biological importance of thiols, the development of probes for thiols has been an active research area in recent years. In this review, we summarize the results of recent exciting reports regarding thiol-addition reactions and their applications in thiol recognition. The examples reported can be classified into four reaction types including 1,1, 1,2, 1,3, 1,4 addition reactions, according to their addition mechanisms, based on different Michael acceptors. In all cases, the reactions are coupled to color and/or emission changes, although some examples dealing with electrochemical recognition have also been included. The use of thiol-addition reactions is a very simple and straightforward procedure for the preparation of thiol-sensing probes.

A tubular molecular rotor B2-Ta@B18− (1) and boron drum Ta@B20− (2) with the highest coordination number of twenty in chemistry are observed via a joint photoelectron spectroscopy and first-principles theory investigation.

The recently observed cage-like borospherenes D2d B40−/0 and C3/C2 B39− have attracted considerable attention in chemistry and materials science. Based on extensive global minimum searches and first-principles theory calculations, we present herein the possibility of cage-like Cs B39+ (1) and Cs B39+ (2) which possess five hexagonal and heptagonal faces and one filled hexagon and follow the bonding pattern of σ + π double delocalization with 12 delocalized π bonds over a σ-skeleton, adding two new members to the borospherene family. IR, Raman, and UV-vis spectra of Cs B39+ (1) and Cs B39+ (2) are computationally simulated to facilitate their experimental characterization.

Low-dimensional materials (LDMs) involving planar hypercoordinate carbon bonding were predicted to have applications in electronic devices, energy materials, and optical materials, etc. The majority of carbon atoms in such LDMs adopt a tetracoordinate structure, while examples with a higher coordination number are extremely rare and the bonding geometries of those carbons are not perfectly planar. In this work, we designed ribbon-like clusters CnBe3n+2H2n+22+ with planar pentacoordinate carbons (ppCs) and extended the corresponding structural model under 1D periodic boundary conditions (PBCs), leading to a zigzag double-chain C–Be nanoribbon. The beryllium atoms in such a nanoribbon arrange in a cosine shape around the perfect ppCs, which are unprecedented in LDMs. Detailed analyses revealed that the perfect ppC structure in the nanoribbon was geometrically achieved by opening a Be–Be edge of small Be5 rings, thereby making the intra-ring space adjustable to fit the size of the carbons. Electronically, the structure is stabilized by a favourable sandwich type charge distribution and satisfaction of the octet rule for ppCs. Note that all the valence electrons in the nanoribbon are locally delocalized within each ppC moiety, representing a new type of ribbon aromaticity, which should be useful in nanoelectronics. The nanoribbon and its cluster precursor C2Be8H62+ are thermodynamically stable, and are promising targets for experimental realization. The nanoribbon was predicted to be an indirect band gap semiconductor; thus it has potential applications in designing light-weight electronic devices.