Abstract Noncovalent interactions play a crucial role in determining the structure, stability, and properties of molecular systems and are essential in supramolecular chemistry, crystal engineering, and materials design. In this study, the intermolecular interactions between phosphinothioformamide (PTF) and HSX molecules (X = F, Cl, Br, and I) were investigated using quantum chemical calculations. Geometry optimizations, vibrational frequency calculations, and interaction energy evaluations were performed at the MP2/aug-cc-pVTZ(PP) level of theory with basis set superposition error (BSSE) correction. The nature of the interactions was further analyzed using Molecular Electrostatic Potential (MEP), Natural Bond Orbital (NBO), and Quantum Theory of Atoms in Molecules (QTAIM) analyses. The results revealed four families of stable complexes (A–D) stabilized by hydrogen, halogen, chalcogen, and pnictogen bonding interactions. MEP analysis identified the preferred interaction sites, while the calculated interaction energies demonstrated the significant influence of the halogen atom on complex stability. NBO analysis confirmed that donor–acceptor charge transfer is an important stabilization mechanism, and QTAIM analysis verified the existence of the predicted noncovalent interactions with predominantly closed-shell character. Overall, the results demonstrate that the nature of the halogen atom and the cooperative effect of different σ-hole interactions govern the stability and electronic properties of the PTF···HSX complexes, providing valuable insight into the rational design of supramolecular systems.
