On the Versatility of the sp-, sp 2-, and sp 3-Hybridized Chalcogen-Bearing Molecules To Engage in Type I Chalcogen<middle dot><middle dot><middle dot>Chalcogen Interactions: A Quantum Mechanical Investigation of Like<middle dot><middle dot><middle dot>Like and Unlike Complexes

The predilection of sp-, sp(2)-, and sp(3)-hybridized chalcogen-bearing molecules to engage in type I chalcogen<middle dot><middle dot><middle dot>chalcogen interactions was comparatively unveiled in like<middle dot><middle dot><middle dot>like/unlike CY<middle dot><middle dot><middle dot>YC, YCY<middle dot><middle dot><middle dot>YCY, and F2Y<middle dot><middle dot><middle dot>YF2 (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; sp(2)- (i.e., YCY<middle dot><middle dot><middle dot>YCY) > sp- (i.e., CY<middle dot><middle dot><middle dot>YC) > sp(3)- (i.e., F2Y<middle dot><middle dot><middle dot>YF2) hybridized complexes, except the like<middle dot><middle dot><middle dot>like oxygen-bearing complexes. Instead, the highest negative binding energy values were detected for the OCO<middle dot><middle dot><middle dot>OCO followed by those of the F2O<middle dot><middle dot><middle dot>OF2 and CO<middle dot><middle dot><middle dot>OC complexes. Furthermore, the like<middle dot><middle dot><middle dot>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<middle dot><middle dot><middle dot>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<middle dot><middle dot><middle dot>chalcogen interactions, leading to increased progress in various domains regarding drug design and materials science.