Reaction-Class-Dependent Intrinsic Barriers Unify Deviant and Multimodal Bell-Evans-Polanyi Behavior in Polar Group...

Area of Science:

• Physical Chemistry
• Organic Chemistry
• Computational Chemistry

Background:

• The Bell-Evans-Polanyi (BEP) relationship links reaction kinetics and thermodynamics, widely used for predicting reactivity.
• Deviations from single BEP correlations are common with structurally diverse reagents, limiting its broad applicability.

Purpose of the Study:

• To explain deviations from BEP correlations using intrinsic barriers.
• To develop a unified framework for predicting reactivity across different reaction classes.

Main Methods:

• Integrated experimental kinetic data with quantum-chemically derived intrinsic barriers from self-exchange reactions.
• Developed an intrinsic barrier augmented linear free energy framework.

Main Results:

• Demonstrated reaction-class-dependent variations in intrinsic barriers explain BEP correlation breakdowns.
• The new framework unifies disparate BEP regimes and improves quantitative agreement with experimental data.
• Successfully predicted Mayr electrophilicity and nucleophilicity parameters for diverse reagents.

Conclusions:

• Systematic variations in intrinsic barriers provide a physical basis for BEP deviations.
• The augmented framework offers a more accurate and general approach to analyzing and predicting chemical reactivity.
• Validated the framework through experimental determination of parameters for new reagents.