A concentric planar doubly π-aromatic B19− cluster

Abstract

Atomic clusters often show unique, size-dependent properties and have become a fertile ground for the discovery of novel molecular structures and chemical bonding. Here we report an investigation of the B₁₉⁻ cluster, which shows chemical bonding reminiscent of that in [10]annulene (C₁₀H₁₀) and [6]circulene (C₂₄H₁₂). Photoelectron spectroscopy reveals a relatively simple spectrum for B₁₉⁻, with a high electron-binding energy. Theoretical calculations show that the global minimum of B₁₉⁻ is a nearly circular planar structure with a central B₆ pentagonal unit bonded to an outer B₁₃ ring. Chemical bonding analyses reveal that the B₁₉⁻ cluster possesses a unique double π-aromaticity in two concentric π-systems, with two π-electrons delocalized over the central pentagonal B₆ unit and another ten π-electrons responsible for the π-bonding between the central pentagonal unit and the outer ring. Such peculiar chemical bonding does not exist in organic compounds; it can only be found in atomic clusters.

Physically founded phonon dispersions of few-layer materials and the case of borophene

“…Theoretical and experimental studies on the quasi-planar B 36 cluster with a central hexagonal hole seem to support this view. [9] However, more recent calculations [10] have predicted two novel 2D boron structures with nonzero thickness that are considerably more stable than the α-sheet.…”

“…[33] In fact, boron displays multiple bulk phases, [33,34] and the formation of clusters, fullerene-type cages and nanotubes made of B is also a subject of ongoing debate. [35][36][37][38][39][40][41][42] The ambientconditions stable phase of B was only recently determined through a series of computational studies, the earliest of which [43] only dates back to 2007. It comes as little surprise, then, that the study of the 2D allotropes of boron has also progressed through iterative improvement upon previous results.…”

Elasticity, Flexibility, and Ideal Strength of Borophenes

“…Since the advent of graphene, 2 twodimensional (2D) materials that are one or several atoms thick reign the current field of materials research. As boron has demonstrated striking similarity to carbon, forming planar clusters 1,[3][4][5][6][7][8] , cage-like fullerences [9][10][11][12][13][14][15] and 1D nanotubes 7,[16][17][18][19][20][21] , extensive theoretical efforts have been devoted to exploring graphene analogues of boron-borophenes [22][23][24][25][26] . Unlike graphene or hexagonal boron nitride (h-BN) that have exclusively stable honeycomb lattice, the borophene is predicted to be polymorphic 27 with numerous states near the ground-state energy line, due to a highly variable network of hollow hexagons (HHs) in a reference triangular lattice.…”

Communication: New insight into electronic shells of metal clusters: Analogues of simple molecules

“…This method was recently developed by Zubarev and Boldyrev 23 and successfully used to analyze chemical bonding in organic molecules and clusters. [23][24][25][26][27][28] AdNDP recovers both Lewis bonding elements and delocalized bonding elements (nc-2e), which is a method of description of the chemical bonding combining the compactness and intuitive simplicity of Lewis theory with the flexibility and generality of canonical MO theory. As shown in Fig.…”