Quantifying interactions in the active encounter complex of frustrated Lewis pairs

Area of Science:

• Catalysis
• Supramolecular Chemistry
• Organometallic Chemistry

Background:

• Frustrated Lewis pairs (FLPs) offer sustainable alternatives to precious metal catalysts.
• The activation of small molecules by FLPs involves a pre-associated encounter complex.
• Understanding the thermodynamics of this complex is crucial for catalyst design.

Purpose of the Study:

• To quantify the association constant (K a) of the active encounter complex in FLP systems.
• To establish a direct relationship between encounter complex concentration and hydrogen activation rates.
• To provide a method for probing the key complex in FLP catalysis.

Main Methods:

• Utilizing supramolecular UV-vis spectroscopic techniques to analyze charge-transfer bands.
• Quantifying the association constant (K a) of the P(mes)3 and B(C6F5)3 encounter complex.
• Correlating encounter complex concentration with the rate of hydrogen activation.

Main Results:

• The association constant (K a) for the active encounter complex was determined using UV-vis spectroscopy.
• A higher concentration of the active encounter complex directly correlates with faster hydrogen activation.
• The study provides direct evidence for the role of the pre-associated complex in FLP catalysis.

Conclusions:

• Supramolecular UV-vis spectroscopy can directly probe the active complex in FLP catalysis.
• The concentration of the active encounter complex is a key determinant of catalytic activity.
• This approach will facilitate the design of more efficient and sustainable FLP catalysts.