Energetic effects between halogen bonds and anion-π or lone pair-π interactions: a theoretical study

Area of Science:

• Supramolecular Chemistry
• Computational Chemistry
• Crystal Engineering

Background:

• Halogen bonds are crucial in crystal engineering.
• Anion-π and lone pair-π interactions influence molecular assembly.
• Understanding combined interaction energetics is key for materials design.

Purpose of the Study:

• To investigate the energetic interplay between halogen bonds and anion-π/lone pair-π interactions.
• To analyze the effects of coexisting these interactions within molecular complexes.
• To elucidate the underlying mechanisms governing these combined interactions.

Main Methods:

• Ab initio MP2 calculations were employed for energetic analysis.
• 1,4-diiodo-perfluorobenzene was used as a model system (halogen bond donor and π-system).
• Analysis included structural, energetic, and Atoms in Molecules (AIM) properties.

Main Results:

• Additive and diminutive energetic effects were observed when halogen bonds and anion-π/lone pair-π interactions coexist.
• These effects are attributed to the concurrent direction of charge transfer in both interaction types.
• Computational findings were supported by experimental evidence from the Cambridge Structural Database.

Conclusions:

• The coexistence of halogen bonds and anion-π/lone pair-π interactions leads to significant energetic consequences.
• Charge transfer directionality is a critical factor in modulating these combined interactions.
• This research provides insights into designing supramolecular architectures with tailored properties.