Intermolecular π-hole/n→π* interactions with carbon monoxide ligands in crystal structures

Area of Science:

• Solid-state chemistry
• Supramolecular chemistry
• Organometallic chemistry

Background:

• Intermolecular interactions are crucial for crystal engineering and material properties.
• Carbon monoxide (CO) is a common ligand in organometallic chemistry, but its role in non-covalent interactions is less explored.
• Understanding these interactions can lead to the design of novel materials and catalysts.

Purpose of the Study:

• To investigate the prevalence and nature of intermolecular interactions involving carbon monoxide ligands in the solid state.
• To quantify the strength and directionality of these interactions using computational methods.
• To explore the influence of metal centers and ligand arrangements on these interactions.

Main Methods:

• Analysis of the Cambridge Structure Database (CSD) for crystal structures containing carbon monoxide ligands.
• Identification and classification of intermolecular interactions, specifically π-hole/n→π* interactions.
• High-level Density Functional Theory (DFT) calculations to determine interaction energies.

Main Results:

• Intermolecular π-hole/n→π* interactions with carbon monoxide ligands are abundant in the solid state.
• These interactions exhibit some directionality, especially with facial M(CO)3 fragments (P < 4.0).
• DFT calculations indicate interaction energies up to approximately -10 kcal mol-1 for adducts of charge-neutral complexes.

Conclusions:

• Carbon monoxide ligands actively participate in significant intermolecular interactions in the solid state.
• The directional nature of these interactions, particularly with specific coordination geometries, offers opportunities for crystal engineering.
• These findings contribute to a deeper understanding of non-covalent forces in organometallic solids and their potential applications.