π-Hole/n→π* interactions with acetonitrile in crystal structures

Area of Science:

• Solid-state chemistry
• Supramolecular chemistry
• Computational chemistry

Background:

• Non-covalent interactions play a crucial role in molecular assembly and material properties.
• Acetonitrile is a common solvent and ligand in coordination chemistry.
• Understanding weak interactions is key to predicting and controlling crystal packing.

Purpose of the Study:

• To investigate the prevalence and characteristics of π-hole/n→π* interactions involving acetonitrile in the solid state.
• To quantify the strength and directionality of these interactions.
• To explore the influence of metal coordination on these interactions.

Main Methods:

• Analysis of the Cambridge Structure Database for relevant crystal structures.
• High-level computational chemistry methods to model interaction energies.

Main Results:

• π-hole/n→π* interactions with acetonitrile are abundant in the solid state.
• These interactions are particularly frequent when acetonitrile is coordinated to a metal center.
• The interactions exhibit weak directionality (P ≤ 1.5).
• Computational studies estimate the complexation energy to be approximately -5 kcal mol-1.

Conclusions:

• Acetonitrile's π-system can act as an acceptor in significant solid-state interactions.
• Metal coordination enhances the occurrence of these interactions, suggesting a role in crystal engineering.
• These findings contribute to the understanding of non-covalent interactions in molecular solids.