One-electron bonds in copper-aluminum and copper-gallium complexes

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• Odd-electron bonds are characterized by unique electronic structures and are typically transient homonuclear species.
• Understanding novel bonding motifs is crucial for developing new materials and chemical transformations.

Purpose of the Study:

• To synthesize and characterize novel copper complexes featuring two-center/one-electron (2c/1e) σ-bonds with heavier Group 13 metalloligands (Al, Ga).
• To investigate the electronic structure, spin delocalization, and bonding nature of these unique Cu-M interactions.

Main Methods:

• Synthesis of copper bimetallic complexes via one-electron reduction of Cu(I) ⇢ M(III) precursors.
• Characterization using X-ray diffraction, cyclic voltammetry, and electron paramagnetic resonance (EPR) spectroscopy.
• Theoretical analysis employing density functional theory (DFT) calculations.

Main Results:

• Successful synthesis of copper complexes incorporating aluminum (Al) and gallium (Ga) metalloligands.
• Experimental and theoretical data confirm the formation of 2c/1e σ-bonds between copper and the Group 13 elements.
• The unpaired spin is delocalized across Cu, M, and ancillary atoms, with the SOMO originating from Cu 4p_z and M ns/np_z orbitals.

Conclusions:

• These findings represent the first examples of odd-electron σ-bonds involving heavier Group 13 elements (Al, Ga).
• The observed interactions exhibit a covalent character, challenging previous notions about bonding in these systems.
• The study provides fundamental insights into the electronic structure and bonding capabilities of metalloligand-supported copper complexes.