[Sb4Au4Sb4](2-): A designer all-metal aromatic sandwich

• Published in: The Journal of chemical physics Vol. 145; no. 4; p. 044308
• Main Authors: Tian, Wen-Juan, Guo, Jin-Chang, Li, Da-Zhi, You, Xue-Rui, Wang, Ying-Jin, Sun, Zhong-Ming, Zhai, Hua-Jin
• Format: Journal Article
• Language: English
• Published: United States 28.07.2016
• Subjects: AROMATICS; BONDING; CHEMICAL BONDS; DESIGN; ELECTRON TRANSFER; ENERGY GAP; EXPERIMENTAL DATA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.4959372

We report on the computational design of an all-metal aromatic sandwich, [Sb4Au4Sb4](2-). The triple-layered, square-prismatic sandwich complex is the global minimum of the system from Coalescence Kick and Minima Hopping structural searches. Following a standard, qualitative chemical bonding analysis via canonical molecular orbitals, the sandwich complex can be formally described as [Sb4](+)[Au4](4-)[Sb4](+), showing ionic bonding characters with electron transfers in between the Sb4/Au4/Sb4 layers. For an in-depth understanding of the system, one needs to go beyond the above picture. Significant Sb → Au donation and Sb ← Au back-donation occur, redistributing electrons from the Sb4/Au4/Sb4 layers to the interlayer Sb-Au-Sb edges, which effectively lead to four Sb-Au-Sb three-center two-electron bonds. The complex is a system with 30 valence electrons, excluding the Sb 5s and Au 5d lone-pairs. The two [Sb4](+) ligands constitute an unusual three-fold (π and σ) aromatic system with all 22 electrons being delocalized. An energy gap of ∼1.6 eV is predicted for this all-metal sandwich. The complex is a rare example for rational design of cluster compounds and invites forth-coming synthetic efforts.