Planar B₃₈⁻and B₃₇⁻clusters with a double-hexagonal vacancy: molecular motifs for borophenes

Abstract

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 B which led to the concept of borophenes and the 3D fullerene-like B which marked the onset of borospherene chemistry. Here, we present a joint photoelectron spectroscopic and first-principles study of B and B, 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 B and B are all-boron analogues of coronene (CH) 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.

Fluxional Bonds in Planar B19−, Tubular Ta@B20−, and Cage‐Like B39−

“…Detailed bonding analyses were performed using the adaptive natural density partitioning (AdNDP) method which recovers both the localized and delocalized bonding elements of the concerned systems. AdNDP has been successfully applied to a wide range of boron and boron‐based nanoclusters . The reaction rate constant k from a true minimum to its transition state neighbor was calculated using Eyring standard transition state theory …”

“…Boron has a strong propensity to form delocalized multi‐center‐two‐electron (mc‐2e) bonds in both bulk allotropes and polyhedral molecules due to its prototypical electron‐deficiency . Persistent joint photoelectron spectroscopy (PES) and first‐principles theory investigations on small monoanionic boron clusters in the past decade have unveiled a rich landscape from planar or quasi‐planar B n −/0 ( n = 3–30, 33–38) to cage‐like borospherenes D 2d B 40 −/0 and C 3 /C 2 B 39 − which are all characterized with delocalized multicenter σ and π bonds . Delocalized bonds have also been reported in metal‐doped boron clusters.…”

Recent Progress on the investigations of boron clusters and boron-based materials (I): borophene

“…间的成键比中心原子之间的成键强且键长较短, 迫使 处于内部的硼原子凸起以平衡内外键长的不匹配 [48] . (硼墨烯)一词 [8] 不应该与国际纯粹与应用化学(Interna- 准平面结构 [41] , 以 及B 40 − 的具有低能量的平面异构体 [37] . 会得到具有类似所谓β-sheet型的多孔硼平面结构 [6] .…”

Boron‐Based Chiral Helix Be6B102− and Be6B11− Clusters: Structures, Chemical Bonding, and Formation Mechanism

“…Owing to boron's electron-deficiency, elemental boron clusters show diverse and unusual nanostructures. An intriguing boron flatland of planar or quasi-planar (2D) clusters [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] was established in the past decades, covering an unprecedented wide range of sizes (up to 40 atoms for anions). [12] Other forms of boron clusters were also reported, such as tubes, [5,8] borospherenes, [12,[16][17][18][19] and borophene.…”