Communication: An unusual halogen-bonding motif: the LiBr···BrF dimer as a model system

Area of Science:

• Chemical Physics
• Computational Chemistry
• Materials Science

Background:

• Diatomic molecules like Lithium Bromide (LiBr) and Bromine Fluoride (BrF) are fundamental chemical species.
• Understanding intermolecular interactions is crucial for predicting chemical behavior and designing new materials.
• Halogen bonding and Lewis acid-base interactions are key non-covalent forces studied in molecular complexes.

Purpose of the Study:

• To computationally investigate the potential formation of stable complexes between Lithium Bromide (LiBr) and Bromine Fluoride (BrF).
• To characterize the nature of bonding in predicted LiBr-BrF complexes, focusing on novel interaction types.
• To compare the stability of the most stable predicted complex with other less stable LiBr-BrF dimers.

Main Methods:

• Utilized computational chemistry methods to predict and model the stable structures of LiBr-BrF complexes.
• Analyzed the electronic structure and bonding characteristics of the predicted complexes, including halogen bonds and Lewis acid-base interactions.
• Calculated interaction energies to determine the relative stability of different predicted dimer configurations.

Main Results:

• Predicted a novel, stable complex, LiBr···BrF, stabilized by a combination of halogen bonding and Lewis acid-base interactions.
• Observed a unique bonding scenario where a bromine atom in BrF interacts with both the lithium cation and bromide anion of LiBr.
• Identified and characterized other less stable LiBr-BrF dimer structures, providing a comparative stability analysis.

Conclusions:

• The study reports the first instance of a diatomic molecule's atom being bonded to two different, oppositely charged atoms of another diatomic molecule.
• The predicted LiBr···BrF complex represents a new structural motif in intermolecular interactions, expanding the understanding of chemical bonding.
• Computational predictions provide a foundation for potential experimental validation and further exploration of such unique molecular assemblies.