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Nature of Bonding in Bowl‐Like B 36 Cluster Revisited: Concentric (6π+18π) Double Aromaticity and Reason for the Preference of a Hexagonal Hole in a Central Location
Author(s) -
Li Rui,
You XueRui,
Wang Kang,
Zhai HuaJin
Publication year - 2018
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201800174
Subject(s) - aromaticity , cluster (spacecraft) , natural bond orbital , crystallography , atomic orbital , coronene , molecular orbital , electron counting , chemistry , chemical physics , molecular physics , density functional theory , electron , physics , computational chemistry , molecule , computer science , quantum mechanics , organic chemistry , programming language
The bowl‐shaped C 6 v B 36 cluster with a central hexagon hole is considered an ideal molecular model for low‐dimensional boron‐based nanosystems. Owing to the electron deficiency of boron, chemical bonding in the B 36 cluster is intriguing, complicated, and has remained elusive despite a couple of papers in the literature. Herein, a bonding analysis is given through canonical molecular orbitals (CMOs) and adaptive natural density partitioning (AdNDP), further aided by natural bond orbital (NBO) analysis and orbital composition calculations. The concerted computational data establish the idea of concentric double π aromaticity for the B 36 cluster, with inner 6π and outer 18π electron counting, which both conform to the (4 n +2) Hückel rule. The updated bonding picture differs from existing knowledge of the system. A refined bonding model is also proposed for coronene, of which the B 36 cluster is an inorganic analogue. It is further shown that concentric double π aromaticity in the B 36 cluster is retained and spatially fixed, irrespective of the migration of the hexagonal hole; the latter process changes the system energetically. The hexagonal hole is a destabilizing factor for σ/π CMOs. The central hexagon hole affects substantially fewer CMOs, thus making the bowl‐shaped C 6 v B 36 cluster the global minimum.