Quantum Tunneling in Peroxide O-O Bond Breaking Reaction

Area of Science:

• Quantum Chemistry
• Chemical Kinetics
• Physical Chemistry

Background:

• Quantum mechanical tunneling is increasingly recognized for its role in chemical reactions, particularly those involving hydrogen and heavier atoms.
• Understanding tunneling mechanisms is vital for predicting reaction pathways and rates in various chemical systems.

Purpose of the Study:

• To investigate concerted heavy-atom tunneling in the oxygen-oxygen bond breaking reaction of cyclic beryllium peroxide.
• To explore the influence of noble gas atom coordination on tunneling rates and reaction kinetics.
• To validate experimental findings with theoretical calculations.

Main Methods:

• Cryogenic Ne matrix isolation of beryllium peroxide (Be(O2)).
• Temperature-dependent kinetic studies to analyze reaction rates.
• Measurement of kinetic isotope effects.
• Quantum chemistry and instanton theory calculations.

Main Results:

• Concerted heavy-atom tunneling was evidenced in the Be(O2) decomposition to linear dioxide.
• Noble gas coordination (Ne, Ar) significantly altered reaction kinetics, increasing the half-life of Be(O2).
• Theoretical calculations supported experimental observations, explaining the reduced reaction rates due to stabilization and increased energy barriers.

Conclusions:

• Noble gas coordination effectively tunes heavy-atom tunneling rates in beryllium peroxide reactions.
• The study provides experimental and theoretical evidence for concerted heavy-atom tunneling.
• Findings highlight the importance of tunneling in chemical bond breaking and the influence of the surrounding matrix environment.