On the Versatility of the -, -, and -Hybridized Chalcogen-Bearing Molecules To Engage in Type I Chalcogen···Chalcogen Interactions: A Quantum Mechanical Investigation of Like···Like and Unlike Complexes.

The predilection of -, -, and -hybridized chalcogen-bearing molecules to engage in type I chalcogen···chalcogen interactions was comparatively unveiled in like···like/unlike CY···YC, YCY···YCY, and FY···YF (where Y = O, S, and Se) complexes, respectively. Upon the optimized monomers, a potential energy surface (PES) scan was conducted to pinpoint the most favorable complexes. The energetic findings unveiled the ability of the investigated systems to engage in the interactions under study with binding energy values ranging from -0.36 to -2.33 kcal/mol. Notably, binding energies were disclosed to align in the posterior sequence; - (i.e., YCY···YCY) > - (i.e., CY···YC) > - (i.e., FY···YF) hybridized complexes, except the like···like oxygen-bearing complexes. Instead, the highest negative binding energy values were detected for the OCO···OCO followed by those of the FO···OF and CO···OC complexes. Furthermore, the like···like selenium-bearing complexes demonstrated the most considerable binding energies compared to the other investigated complexes. Remarkably, the quantum theory of atoms in molecules and noncovalent interaction index analyses revealed the highly directional and closed-shell nature of the investigated chalcogen···chalcogen interactions. Symmetry adapted-perturbation theory findings outlined the dispersion forces as the commanding forces for all the studied complexes. These observations will provide convincing justifications for the nature of chalcogens within type I chalcogen···chalcogen interactions, leading to increased progress in various domains regarding drug design and materials science.