Nature of Bonding in Bowl-Like B36 Cluster Revisited: Concentric (6+18) Double Aromaticity and Reason for the Preference of a Hexagonal Hole in a Central Location

作者：Li, Rui; You, Xue-Rui; Wang, Kang; Zhai, Hua-Jin^*

来源：Chemistry-An Asian Journal, 2018, 13(9): 1148-1156.

DOI：10.1002/asia.201800174

• aromaticity
• bond theory
• boron
• cluster compounds
• density functional calculations

The bowl-shaped C-6v 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 aromaticity for the B-36 cluster, with inner 6 and outer 18 electron counting, which both conform to the (4n+2) Huckel 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 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 sigma/ CMOs. The central hexagon hole affects substantially fewer CMOs, thus making the bowl-shaped C-6v B-36 cluster the global minimum.

• 出版日期2018-5-4
• 单位山西大学