Intramolecular pnicogen interactions in PHF-(CH2)(n)-PHF (n=2-6) systems

Area of Science:

• Computational Chemistry
• Supramolecular Chemistry
• Organic Chemistry

Background:

• Intramolecular pnicogen bonds are crucial in molecular recognition and crystal engineering.
• Understanding these interactions requires detailed computational analysis of their energetic and electronic properties.

Purpose of the Study:

• To computationally investigate the intramolecular pnicogen bond in PHF-(CH2)n-PHF systems.
• To compare the stability and characteristics of closed versus extended conformations.
• To analyze the nature of the P-P interaction and its relationship with chemical shielding.

Main Methods:

• Density Functional Theory (DFT) calculations were employed.
• Isodesmic reactions were used to calculate interaction energies.
• Atoms in Molecules (AIM) and Electron Localization Function (ELF) analyses were performed.
• Cambridge Crystallographic Database search for solid-state evidence.

Main Results:

• Closed conformations were found to be more stable than extended ones in several cases.
• Interaction energies ranged from -3.4 to -26.0 kJ/mol, indicating significant pnicogen bonding.
• AIM and ELF analyses revealed partial covalent character in the P-P interaction.
• An exponential relationship was observed between P atom chemical shielding and P-P distance.

Conclusions:

• Intramolecular pnicogen bonds in PHF-(CH2)n-PHF systems are energetically favorable and possess partial covalent character.
• Conformational preferences significantly influence the strength and nature of these interactions.
• The findings provide insights into the factors governing pnicogen bond formation and strength.