Theoretical and conceptual DFT study of pnicogen- and halogen-bonded complexes of PH2X---BrCl.

Abstract

The pnicogen and halogen bonding interactions in the PH2X---BrCl(X = H, F, OH, OCH3 and CH3) complexes have been studied at the MP2/aug-cc-pVTZ level. Analysis of interaction energies shows that the pnicogen-bonded structures are less stable than the corresponding halogen-bonded structures. The pnicogen and halogen bonds were also studied by conceptual DFT reactivity indices. Noncovalent interaction (NCI) and SAPT analysis reveals that the dispersion interactions dominate the pnicogen-bonded complexes of PH2X---BrCl in nature, while the halogen-bonded complexes are dominantly electrostatic energy. Graphical abstract It is found that the local softness s+ or s-on the basic center P of PH2X is related to the interaction energies (ΔECP) of halogen- or pnicogen-bonded complexes.