Sb(η⁶-Be₆H₆)Sb and Bi(η⁶-Be₆H₆)Bi: Double Aromatic Inverse-Sandwich Complexes.

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Materials Science

Background:

• Beryllium hydride (Be$_{n}$H$_{n}$) rings are isoelectronic with boron rings, offering potential for novel bonding and geometries.
• Inverse-sandwich complexes, where a ring system is sandwiched between two metal atoms, are of significant interest in coordination chemistry.
• Understanding the stability and electronic structure of such complexes is crucial for designing new materials.

Purpose of the Study:

• To report the synthesis and characterization of the first Be$_{n}$H$_{n}$-based inverse-sandwich complexes.
• To investigate the structural, bonding, and electronic properties of M$_{2}$Be$_{6}$H$_{6}$ (M = N, P, As, Sb, or Bi) complexes.
• To explore the factors contributing to the stability of these novel compounds.

Main Methods:

• Computational modeling was employed to analyze the potential energy surfaces of M$_{2}$Be$_{6}$H$_{6}$ systems.
• Density Functional Theory (DFT) calculations were used to determine the geometries and electronic structures.
• Analysis of charge transfer, delocalized bonding (14c-2e $\sigma$ and 8c-2e $\pi$ bonds), and aromaticity was performed.

Main Results:

• Sb$_{2}$Be$_{6}$H$_{6}$ and Bi$_{2}$Be$_{6}$H$_{6}$ were identified as global minima with inverse-sandwich geometries.
• The structures feature a central Be$_{6}$H$_{6}$ ring with D$_{6h}$ symmetry, sandwiched between two Sb or Bi atoms.
• Strong charge transfer from the Be$_{6}$H$_{6}$ ring to the metal atoms and dual Hückel aromaticity contribute to exceptional stability.

Conclusions:

• The study successfully demonstrates the formation of stable Be$_{n}$H$_{n}$-based inverse-sandwich complexes.
• Sb$_{2}$Be$_{6}$H$_{6}$ and Bi$_{2}$Be$_{6}$H$_{6}$ represent a new class of inorganic compounds with unique structural and electronic features.
• The findings highlight the potential of Be$_{n}$H$_{n}$ rings in designing exotic coordination compounds with dual aromaticity.