Ab Initio Approach to the Structure, Vibrational Properties, and Electron Binding Energies of H(2)S∙∙∙SO(2)

The present study employs high-level ab initio calculations to investigate the structure, vibrational frequencies, and electronic properties of H(2)S∙∙∙SO(2). The analysis of vibrational frequencies reveals an intramolecular vibrational energy transfer phenomenon, where energy from the stretching modes of H(2)S is transferred to the ν1s mode of SO(2). At the CCSD(T)/aug-cc-pVQZ level, the interaction energy between H(2)S and SO(2) is predicted to be 2.78 kcal/mol. Electron propagator theory calculations yield a HOMO–LUMO gap of 8.24 eV for H(2)S∙∙∙SO(2). Furthermore, by utilizing ab initio results for the adiabatic ionization energy and electron affinity, the electrophilicity of H(2)S∙∙∙SO(2) is estimated to be 2.01 eV. This value is similar to the electrophilicity of SO(2), suggesting comparable reactivity and chemical behavior. The non-covalent interaction (NCI) analysis of the H(2)S∙∙∙SO(2) complex emphasizes the significant contribution of non-covalent van der Waals interactions in its energetic stabilization.