Hepta‐ and Octacoordinate Boron in Molecular Wheels of Eight‐ and Nine‐Atom Boron Clusters: Observation and Confirmation

Zhai, Hua‐Jin; Alexandrova, Anastassia N.; Birch, Kean; Boldyrev, Alexander I.; Wang, Lai-Sheng

doi:10.1002/anie.200351874

Cited by 493 publications

(545 citation statements)

References 21 publications

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“…In contrast, due to the delocalized p-type bonding in the X-direction, almost no gap appears along K X with the uppermost valence band crossing the Fermi level. The calculated band gap at C along K Y for the {1 2 2 1} sheet is $0.45 eV, which is smaller than the calculated indirect band gap of 1.72 eV found in crystalline a-B 12 [17]. The idealized {1 2 1 2} sheet is predicted to be metallic with finite density of states at the Fermi energy.…”

mentioning

confidence: 60%

“…In this context, it is worth pointing out that the 2D sheets share some similarities in electronic properties with their fragments, namely, the planar boron clusters [6,17]. The dominant feature of out-of-plane p-type bonding interactions resulting in delocalized charge density in the idealized {1 2 1 2} sheet can be attributed to the delocalized nature of the p-electrons in the planar boron clusters, which renders aromaticity and antiaromaticity to the corresponding clusters in analogy to bonding in planar hydrocarbons [6,17].…”

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confidence: 99%

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First-principles study of the stability and electronic properties of sheets and nanotubes of elemental boron

Lau

Pati

Pandey

et al. 2006

Chemical Physics Letters

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confidence: 60%

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confidence: 99%

First-principles study of the stability and electronic properties of sheets and nanotubes of elemental boron

Lau

Pati

Pandey

et al. 2006

Chemical Physics Letters

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“…These remarkable properties lead boron to potentially important applications such as high-temperature semiconductors, 7 superconductor, 8 and high-energy density fuels. 9,10 Over the past few years, boron nanostructures have been extensively investigated both theoretically 1-3, [11][12][13][14][15][16][17][18][19][20][21] and experimentally. [14][15][16][17] The growing research interests are largely driven by the technological challenges of miniaturization of electronic devices.…”

Section: Introductionmentioning

confidence: 99%

“…2, [11][12][13][14][15][16][17] Recently, a combined experimental/simulated photoelectron spectroscopy study suggests that a planar-to-tubular structural transition is likely to occur at n =20 ͑Ref. 17͒ and beyond n = 20, 3D B n clusters become the energetically more stable structure.…”

Section: Introductionmentioning

confidence: 99%

Relative stability of planar versus double-ring tubular isomers of neutral and anionic boron cluster B20 and B20−

Bulusu

Gao

et al. 2006

The Journal of Chemical Physics

106

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High-level ab initio molecular-orbital methods have been employed to determine the relative stability among four neutral and anionic B 20 isomers, particularly the double-ring tubular isomer versus three low-lying planar isomers. Calculations with the fourth-order Møller-Plessset perturbation theory ͓MP4͑SDQ͔͒ and Dunning's correlation consistent polarized valence triple zeta basis set as well as with the coupled-cluster method including single, double, and noniteratively perturbative triple excitations and the 6-311G͑d͒ basis set show that the double-ring tubular isomer is appreciably lower in energy than the three planar isomers and is thus likely the global minimum of neutral B 20 cluster. In contrast, calculations with the MP4͑SDQ͒ level of theory and 6-311 +G͑d͒ basis set show that the double-ring anion isomer is appreciably higher in energy than two of the three planar isomers. In addition, the temperature effects on the relative stability of both 10 B 20 − and 11 B 20 − anion isomers are examined using the density-functional theory. It is found that the three planar anion isomers become increasingly more stable than the double-ring isomer with increasing the temperature. These results are consistent with the previous conclusion based on a joint experimental/simulated anion photoelectron spectroscopy study ͓B. Kiran et al., Proc. Natl. Acad. Sci. U.S.A. 102, 961 ͑2005͔͒, that is, the double-ring anion isomer is notably absent from the experimental spectra. The high stability of the double-ring neutral isomer of B 20 can be attributed in part to the strong aromaticity as charaterized by its large negative nucleus-independent chemical shift. The high-level ab initio calculations suggest that the planar-to-tubular structural transition starts at B 20 for neutral clusters but should occur beyond the size of B 20 − for the anion clusters.

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“…1, 2 Boron is characterized by a short covalent radius and has the tendency to form strong and directional chemical bonds. 1,2 These characteristics lead to a large diversity of boron nanostructures -clusters, 3,4,5,6,7 nanowires, 8 and nanotubes 9,10 -that have already been observed.…”

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confidence: 99%

The planar-to-tubular structural transition in boron clusters from optical absorption

Marques

Botti

2005

The Journal of Chemical Physics

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The optical response of the lowest energy isomers of the B20 family is calculated using timedependent density functional theory within a real-space, real-time scheme. Significant differences are found among the absorption spectra of the clusters studied. We show that these differences can be easily related to changes in the overall geometry. Optical spectroscopy is thus an efficient tool to characterize the planar to tubular structural transition, known to be present in these boron based systems.PACS numbers: 78.67. Bf, 64.70.Nd, 71.15.Mb For the past years, boron nanostructures have attracted the attention of both theoretical and experimental physicists. This is due to the remarkable properties of boron, that make it an unique element in the periodic table, with important technological applications. 1,2 Boron is characterized by a short covalent radius and has the tendency to form strong and directional chemical bonds. 1,2 These characteristics lead to a large diversity of boron nanostructures -clusters, 3,4,5,6,7 nanowires, 8 and nanotubes 9,10 -that have already been observed.Many experimental studies of small boron-based clusters have been performed in the last decade, namely using mass and photo-electron spectroscopies. 3,4,5,7 However, we still have very limited information regarding the geometries and electronic properties of these systems. From the theoretical point of view, there have been extensive ab initio quantum chemical and density functional calculations about the structural properties of neutral, 3,5,7,11,12,13,14,15,16 cationic, 15,17,18 and anionic clusters. 5,7 The findings were fairly surprising. In fact, bulk boron appears in several crystalline and amorphous phases, the best know of which are the α-and β-rombohedral, and the α-tetragonal, also known as low temperature or red boron. In these three phases, boron is arranged in B 12 icosahedra 1,19,20 (in the α-tetragonal phase these icosahedra are slightly distorted). However, the small clusters appear in four distinct shapes: 16 convex, spherical, quasi-planar, and nanotubular -totally unrelated to the B 12 icosahedra.The most stable members of the B n family with n 20 are known to be planar. 3,5,11,12,13,14,15 Recent calculations showed that B n clusters with n = 24 and n = 32 prefer tubular structures. 16 In a recent study 7 Kiran et al. placed the transition between these two topologies at n = 20. However, their results were not totally conclusive: while the theoretical calculations (using density functional theory at the B3LYP/6-311+G * level) yielded a double ring arrangement as the lowest energy isomer of B 20 and B − 20 , the experimental photo-electron spectra of anionic aggregates of the same size were only compatible with planar structures. Such a incongruity can be explained by the difficulties associated both to the experimental and numerical techniques. Experimentally, the clusters were produced by laser evaporation of a disk target, with the formation of the fragments being mainly controlled by kinematics. The situation is...

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Hepta‐ and Octacoordinate Boron in Molecular Wheels of Eight‐ and Nine‐Atom Boron Clusters: Observation and Confirmation

Cited by 493 publications

References 21 publications

First-principles study of the stability and electronic properties of sheets and nanotubes of elemental boron

First-principles study of the stability and electronic properties of sheets and nanotubes of elemental boron

Relative stability of planar versus double-ring tubular isomers of neutral and anionic boron cluster B20 and B20−

The planar-to-tubular structural transition in boron clusters from optical absorption

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