On the correlation between bond-length change and vibrational frequency shift in halogen-bonded complexes

Area of Science:

• Computational Chemistry
• Chemical Physics
• Spectroscopy

Background:

• Halogen bonds (C-Hal···Y) are crucial non-covalent interactions.
• Understanding these interactions requires analyzing bond length and vibrational frequency changes.

Purpose of the Study:

• To investigate the relationship between C-Hal bond length changes and C-Hal stretch vibrational frequency shifts upon halogen bond formation.
• To assess the reliability of this correlation using computational methods.

Main Methods:

• Density functional theory (DFT) computations were employed.
• Calculations focused on C-Hal bond length changes and vibrational frequency shifts in various halogen-bonded complexes.
• Statistical analysis, including coefficient of determination, was used to evaluate the correlation.

Main Results:

• A strong linear correlation was observed between C-Hal bond length changes and C-Hal stretch vibrational frequency shifts.
• Coefficients of determination ranged from 0.94366 to 0.99219, indicating a very good correlation.
• The correlation holds across different C-Hal bonds (Cl, Br, I) and electron donors (Y).

Conclusions:

• The study confirms a robust linear relationship between geometric and spectroscopic parameters in halogen bonding.
• This correlation provides a valuable tool for characterizing and predicting halogen bond strength and properties.
• The findings are important for fields utilizing non-covalent interactions, such as supramolecular chemistry and drug design.