Unconventional Radical and Radical-Hole Site-Based Interactions in Halogen-Bearing Dimers and Trimers: A Comparative...

Area of Science:

• Computational Chemistry
• Supramolecular Chemistry
• Chemical Physics

Background:

• Radical (R•) and R•-hole site interactions are crucial in chemical bonding.
• Understanding these interactions is key for supramolecular chemistry and crystal engineering.

Purpose of the Study:

• To comparatively study radical (R•) and R•-hole site-based interactions using ab initio methods.
• To investigate the interaction of R•-bearing molecules (•XO3, X=Cl, Br, I) with ammonia (NH3) in dimeric and trimeric forms.
• To analyze the Lewis acid potential of •XO3 molecules and their interaction sites.

Main Methods:

• Ab initio computational methods were employed.
• Electrostatic potential analysis was used to identify interaction sites.
• Interaction energies (Eint) were calculated for various complexes.

Main Results:

• •XO3 molecules exhibit potential as Lewis acids, interacting via R• and R•-hole sites.
• Negative interaction energies (–4.93 to –19.89 kcal/mol) confirm favorable interactions.
• R• site interactions were generally preferred over R•-hole site interactions, with exceptions for iodine-based complexes.
• Trimeric complexes showed stronger interactions than dimeric ones.
• MP2 calculations provided further insights into interaction preferences.

Conclusions:

• •XO3 molecules can engage in both unconventional R• and established R•-hole site interactions with Lewis bases like NH3.
• The study provides a foundation for future research in supramolecular chemistry and crystal engineering.
• Interaction preferences vary based on the halogen atom (X) and the aggregation state (dimer vs. trimer).