A New Family of Bare and NHC‐Ligand‐Stabilized Planar Hexacoordinate Boron Species: Be ₂ B ₄ CE ⁺

The occurrence of planar hexacoordination is of interest for main‐group elements in the periodic table. In this study, we investigated the potential energy surfaces (PES) of Be ₂ B ₄ CE clusters ( E  = N, P, As, Sb, and Bi) across their neutral, mono‐cationic, mono‐anionic, di‐cationic, and di‐anionic charge states using density functional theory (DFT). Among these, Be ₂ B ₄ CN ⁺ , Be ₂ B ₄ CP ⁺ , and Be ₂ B ₄ CAs ⁺ clusters exhibit a true planar hexacoordinate boron (phB) atom in their global minimum energy structures, all possessing C _s symmetry. In the case of the phB structure for the Be ₂ B ₄ CN ⁺ system, the N atom is connected to the phB atom, whereas for other phB structures, there is no connection between the central boron atom and the E atoms. Natural charge analysis revealed that in the phB structure of the Be ₂ B ₄ CN ⁺ , the central boron atom is slightly negative, while it is notably negative for Be ₂ B ₄ CP ⁺ and Be ₂ B ₄ CAs ⁺ systems. Nucleus‐independent chemical shift (NICS) calculations confirm that the phB structures possess σ / π ‐dual aromaticity. The most intriguing finding is that the planar geometry of the phB center remains intact upon coordination with the N‐heterocyclic carbene (NHC) ligand.