Confirmed by X-ray crystallography: the B⋅B one-electron σ bond

Area of Science:

• Inorganic Chemistry
• Quantum Chemistry
• Materials Science

Background:

• The conventional understanding of chemical bonds involves shared electron pairs.
• Experimental evidence for one-electron sigma bonds, especially between homonuclear atoms, is scarce.
• Previous identifications relied primarily on spectroscopic data.

Purpose of the Study:

• To provide the first crystallographic characterization of a one-electron sigma bond.
• To validate the existence and nature of such a bond using quantum-chemical methods.
• To challenge the established electron-pair model of chemical bonding.

Main Methods:

• X-ray crystallography for structural determination.
• Quantum-chemical calculations for theoretical validation.
• Synthesis and characterization of a novel radical anion.

Main Results:

• Successful crystallographic determination of a radical anion containing a B-B one-electron-two-center sigma bond.
• Quantum-chemical analysis confirmed the stability and characteristics of the one-electron bond.
• The results provide concrete structural evidence for this unusual bonding motif.

Conclusions:

• One electron is sufficient to form a significant sigma bond between two boron atoms.
• This work provides a new perspective on chemical bonding, expanding beyond the electron-pair model.
• The findings open avenues for exploring new chemical species with novel bonding.