Modulating of the pnicogen-bonding by a H⋯π interaction: An ab initio study

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Supramolecular Chemistry

Background:

• Pnicogen bonding and H⋯π interactions are crucial non-covalent forces in molecular recognition.
• Understanding cooperativity between different non-covalent interactions is key to designing novel materials and predicting molecular behavior.

Purpose of the Study:

• To investigate the cooperative effects between pnicogen-bonding (P⋯N/C) and H⋯π interactions in ternary molecular complexes.
• To analyze the influence of different substituents (X and Z) on the strength and nature of these cooperative interactions.

Main Methods:

• Ab initio computational study using the MP2 method.
• Detailed analysis of molecular structures, interaction energies, and bonding properties.
• Application of the Quantum Theory of Atoms in Molecules (QTAIM) to examine electron density distribution.

Main Results:

• Favorable cooperativity was observed in all studied complexes, particularly for X=F and X=CN.
• XH2P⋯CNH⋯Z complexes exhibited stronger cooperativity than XH2P⋯NCH⋯Z counterparts.
• H⋯π interactions had a more pronounced influence on P⋯N(C) bonds than vice versa.
• Ternary complexes showed increased electron densities at bond critical points compared to binary systems.
• Solvent presence was found to enhance the strength of both P⋯N(C) and H⋯π interactions.

Conclusions:

• Synergistic effects between pnicogen bonding and H⋯π interactions significantly stabilize molecular complexes.
• The electronic nature of substituents and the specific arrangement of interacting groups modulate the cooperativity.
• These findings provide insights into the design of supramolecular assemblies and understanding intermolecular forces in condensed phases.