Visualization of Electron Density Changes Along Chemical Reaction Pathways.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Chemical Physics

Background:

• Visualizing electron density changes (EDC) is crucial for understanding chemical reaction mechanisms.
• Current methods may lack simplicity or direct correlation with atomic motion.
• Analyzing minimum energy pathways (MEP) requires detailed electronic structure information.

Purpose of the Study:

• To introduce a simple and intuitive procedure for visualizing electron density changes (EDC) during chemical reactions.
• To demonstrate the effectiveness of the proposed method across various reaction types.
• To provide insights into bond evolution and electronic structure changes along reaction pathways.

Main Methods:

• Mapping rectangular grid points from a reference structure to a target structure.
• Calculating grid point displacements as a linear combination of atomic motions, weighted by Hirshfeld analysis.
• Applying the method to diverse reactions including S₂, Claisen rearrangement, Diels-Alder, [3+2] cycloaddition, and N₂O fragmentation.

Main Results:

• EDC plots accurately depicted electron density reduction around bond breaking and increase around bond formation.
• The method successfully visualized bond weakening in copper triflate catalyzed N₂O fragmentation, including transitions between singlet and triplet surfaces.
• Visualizations showed clear correlations between electronic density redistribution and chemical bond changes.

Conclusions:

• The proposed procedure offers a simple and effective way to visualize electron density changes during chemical reactions.
• This method provides valuable insights into reaction mechanisms by highlighting electronic redistribution.
• The technique is applicable to a wide range of chemical transformations and electronic structure phenomena.