A designer 32-electron superatomic CBe8H12 cluster: core–shell geometry, octacoordinate carbon, and cubic aromaticity

Abstract

Cubic octacoordinate carbon (coC) systems are extremely rare in chemistry. We report on a designer 32-electron coC CBe₈H₁₂ cluster, which has high O_h symmetry, being robust chemically and electronically, as well as dynamically up to 1200 K. Chemical bonding analysis establishes it as a core–shell cluster, consisting of cubic Be₈H₁₂ shell versus coC CBe₈ core. The former is bound via Lewis-type three-center two-electron (3c-2e) Be–H–Be σ bonds and the latter features 8σ cubic aromaticity, collectively leading to a two-fold superatomic electron configuration. Cubic 8σ delocalization occurs in a truly three-dimensional fashion within the coC core, rather than on square surfaces only. The C center is in the s¹p³ configuration, which uses 2s/2p_x/2p_y/2p_z atomic orbitals equally in bonding with the Be₈ cube, albeit without sp³ hybridization. The cubic cluster concept can be extended to alternative O_h Be₈H₁₂²⁺ and NBe₈H₁₂⁺ clusters, the latter being a superalkali cation, which offers opportunities to tune the electronic properties.