Bismuth-Boron Multiple Bonding in BiB₂ O^- and Bi₂ B

Area of Science:

• Inorganic Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Boron's electron deficiency typically limits its bonding capabilities.
• While transition-metal-boron double bonds are known, boron-metal triple bonds have remained experimentally unobserved.
• Understanding the limits of main-group element bonding is crucial for designing new materials.

Purpose of the Study:

• To experimentally synthesize and characterize novel bismuth-boron cluster anions.
• To investigate the presence and nature of multiple bonding between bismuth and boron.
• To explore the potential for designing new main-group metal-boron complexes.

Main Methods:

• Laser vaporization of a mixed boron/bismuth target to produce cluster anions.
• Photoelectron spectroscopy for characterizing the electronic structure of the anions.
• Ab initio calculations to interpret experimental data and analyze chemical bonding.

Main Results:

• Successful synthesis and characterization of two bismuth-boron cluster anions: BiB2O- and Bi2B-.
• Experimental and computational evidence for linear structures of both anions.
• Observation of bismuth-boron triple bonds in BiB2O- ([Bi≡B-B≡O]-) and double bonds in Bi2B- ([Bi=B=Bi]-).
• Calculated bond strengths of 4.70 eV for Bi-B triple bonds and 3.21 eV for Bi-B double bonds.

Conclusions:

• This study provides the first experimental evidence of bismuth-boron double and triple bonds.
• The findings expand the known chemistry of boron and main-group metal bonding.
• Opens new avenues for the rational design of main-group metal-boron complexes featuring multiple bonding.