An All-Metal Aromatic Sandwich Complex [Sb3Au3Sb3](3-)

Area of Science:

• Inorganic Chemistry
• Materials Science
• Computational Chemistry

Background:

• Traditional sandwich complexes involve a metal center between two arene ligands.
• Previous extensions included carbon-free ligands and multi-metal centers but not all-metal species.
• The definition of aromaticity in metallic systems is an active area of research.

Purpose of the Study:

• To synthesize and characterize a novel all-metal aromatic sandwich complex.
• To investigate the electronic structure and bonding in this unprecedented complex.
• To explore the aromaticity of metallic layers in a sandwich structure.

Main Methods:

• Synthesis of the [Sb3Au3Sb3](3-) complex.
• Isolation and characterization using K([2.2.2]crypt)(+) salt.
• Single-crystal X-ray diffraction analysis.
• Quantum chemical calculations.

Main Results:

• Successful synthesis and structural identification of the all-metal sandwich complex [Sb3Au3Sb3](3-).
• Quantum chemical calculations revealed significant intramolecular electron transfer between Sb and Au layers.
• The cyclo-Sb3 ligands exhibit aromaticity via delocalized three-center, three-electron (3c-3e) π bonds.
• The bonding is primarily σ-based, stabilized by electron redistribution.

Conclusions:

• The study reports the first all-metal aromatic sandwich complex, [Sb3Au3Sb3](3-).
• Electron transfer and σ-bonding are key to the stability of this unique structure.
• The cyclo-Sb3 units display aromaticity consistent with a reversed 4n Hückel rule for triplet states.