Rotation about a Covalent Bond and Pyramidalization of an Adjacent sp² Center are a Synchronized Molecular Motion

Area of Science:

• Organic Chemistry
• Structural Chemistry
• Computational Chemistry

Background:

• The study builds upon previous work identifying a link between rotation and pyramidalization in methyl acetates.
• The generalization extends the analysis to a broader range of chemical substructures and functional groups.

Purpose of the Study:

• To investigate the correlation between Cα-C' bond rotation and sp2 carbon pyramidalization in various chemical substructures.
• To analyze a large dataset of organic molecules to understand common molecular motions.

Main Methods:

• Analysis of several hundred thousand structures from the Cambridge Structural Database (CSD).
• Utilized ψ/θ scatter plots and averaged curves (ψ/θav) to visualize molecular dynamics.
• Employed Density Functional Theory (DFT) calculations to validate findings.

Main Results:

• Confirmed that rotation about the Cα-C' bond and pyramidalization are coupled, representing a single molecular motion.
• Observed wavelike patterns with specific symmetries in the structural dynamics across diverse compounds.
• Demonstrated that pyramidalization can even affect the planarity of aromatic systems like phenyl rings.

Conclusions:

• The findings reveal a fundamental, interconnected molecular motion applicable to a wide range of organic functional groups.
• The study provides insights into the conformational flexibility and dynamics of organic molecules.
• Computational validation supports the experimental observations from the CSD search.