Unusual Chalcogen∙∙∙Chalcogen Interactions in Like∙∙∙Like and Unlike Y=C=Y∙∙∙Y=C=Y Complexes (Y = O, S, and Se)

Chalcogen∙∙∙Chalcogen interactions were investigated within four types of like∙∙∙like and unlike Y=C=Y∙∙∙Y=C=Y complexes (where Y = O, S, and Se). A plethora of quantum mechanical calculations, including molecular electrostatic potential (MEP), maximum surface electrostatic potential (Vs,max), point-of-charge (PoC), quantum theory of atoms in molecules (QTAIM), noncovalent interaction (NCI), and symmetry-adapted perturbation theory-based energy decomposition analysis (SAPT-EDA) calculations, were executed. The energetic findings revealed a preferential tendency of the studied chalcogen-bearing molecules to engage in type I, II, III, and IV chalcogen∙∙∙chalcogen interactions. Notably, the selenium-bearing molecules exhibited the most potent ability to favorably participate in all the explored chalcogen∙∙∙chalcogen interactions. Among like∙∙∙like complexes, type IV interactions showed the most favorable negative binding energies, whereas type III interactions exhibited the scrawniest binding energies. Unexpectedly, oxygen-containing complexes within type IV interactions showed an alien pattern of binding energies that decreased along with the chalcogen atomic size level up. QTAIM analysis provided a solo BCP, via chalcogen∙∙∙chalcogen interactions, with no clues for any secondary ones. SAPT-EDA outlined the domination of the explored interactions by the dispersion forces and indicated to the pivotal shares of the electrostatic forces, except type III σ-hole∙∙∙σ-hole and di σ-hole interactions. These observations demonstrate in better detail all types of chalcogen∙∙∙chalcogen interactions, leading to a persuasive intensification for versatile fields related to materials science and drug design.