Sandwich complexes based on the "all-metal" Al4 2- aromatic ring.

Area of Science:

• Inorganic Chemistry
• Materials Science
• Computational Chemistry

Background:

• Recent synthesis of the all-metal aromatic tetraaluminum (Al4(2-)) square ring.
• Exploration of novel structural motifs incorporating aromatic rings.
• Understanding the electronic properties and stability of metal clusters.

Purpose of the Study:

• To synthesize and characterize novel sandwichlike structures incorporating the Al4(2-) ring.
• To investigate the role of transition metals (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) in these structures.
• To evaluate the stability of the resulting anionic complexes, particularly towards electron detachment.

Main Methods:

• Theoretical calculations to predict and analyze the structure and stability of [Al4MAl4](q-) complexes.
• Investigation of electron detachment energies for various charge states (q=0-2).
• Computational modeling to assess the impact of alkali cation addition on complex stability.

Main Results:

• Successful design of sandwichlike structures [Al4MAl4](q-) with trapped transition metal cations.
• Demonstration that alkali cations stabilize the doubly charged complexes (q=2), preventing spontaneous electron detachment.
• Preservation of the aromatic character of the Al4(2-) square rings within the sandwichlike complexes.

Conclusions:

• The synthesized sandwichlike structures are stable and represent a new class of inorganic compounds.
• The Al4(2-) aromatic core remains intact upon complex formation, validating its inherent stability.
• Alkali metal addition is a viable strategy for stabilizing highly charged metal-organic complexes.