Double σ-Aromaticity in a Planar Zinc-Doped Gold Cluster: Au₉Zn^–

Abstract

The strong relativistic effects result in many interesting chemical and physical properties for gold and gold compounds. One of the most surprising findings has been that small gold clusters prefer planar structures. Dopants can be used to tune the electronic and structural properties of gold nanoclusters. Here we report an experimental and theoretical investigation of a Zn-doped gold cluster, Au9Zn–. Photoelectron spectroscopy reveals that Au9Zn– is a highly stable electronic system with an electron binding energy of 4.27 eV. Quantum chemical studies show that the global minimum of Au9Zn– has a D 3h structure with a closed-shell electron configuration (1A1’), which can be viewed as replacing the central Au atom by Zn in the open-shell parent Au10 – cluster. The high electronic stability of Au9Zn– is corroborated by its extremely large HOMO–LUMO gap of 3.3 eV. Chemical bonding analyses revealed that the D 3h Au9Zn– are bonded by two sets of delocalized σ bonds, giving rise to double σ aromaticity and its remarkable stability. Two planar low-lying isomers are also observed, corresponding to a similar triangular structure with the Zn atom on the edge and another one with one of the corner Au atoms moved to the edge of the triangle.

σ-Aromaticity Planar Pentacoordinate Beryllium Atoms

“…The rule-breaking bonding usually requiring new considerations upon classical bonding models, especially an effective electronic design scheme, is a key issue to excavate them. − The highly delocalized bonding originating from the active participation of p/d π electrons of the central atom has been proven to facilitate planar hypercoordinate main-group/transition metals. − For instance, the fully delocalized π electrons of the central p z lone pair reinforced by π-acceptor/σ-donor ligands can effectively stabilize the high-symmetry planar hypercoordinate carbon or other main-group atoms, making the mixed π/σ-aromatic species according to the 4 n + 2 rule. − The dual σ + π aromaticity is responsible for highly stable transition-metal-centered borometallic molecular wheels. ,− It is worth noting that the σ aromaticity alone has been found to provide a crucial electronic stabilization factor for planar hypercoordinate clusters, but it is limited to transition metals. − …”

Photoelectron Spectroscopy of Size-Selected Bismuth–Boron Clusters: BiBn– (n = 6–8)

“…The adaptive natural density partitioning (AdNDP) method , was used for the chemical bonding analyses as a time-proven probe for deciphering delocalized bonding in various chemical systems. − The algorithm works within a concept of occupation numbers (ONs), such that the closer an ON of a certain bond is to 2.0 (1.0 for single-electron bonds), the more reliable the bonding picture is.…”

Band Gap Engineering and 14 Electron Superatoms in 2D Superoctahedral Boranes B4X2 (B, N, P, As, Sb)

“…The thermal stability of monolayers was tested through Born–Oppenheimer molecular dynamics (BOMD) simulations invoking the NVT ensemble with the temperature increment of 100 K. The temperature control during BOMD runs was based on the Nosé thermostat model . To get insight into the bonding of B 4 As 2 , we used the SSAdNDP code, an extension of the original AdNDP approach applicable to wide variety of non-periodic systems − exhibiting localized and delocalized bonding patterns. All structures and bonding elements were visualized by Vesta suite .…”