Ab initio investigation for π-hole interactions of tetrel- and aerogen-bearing molecules with multiple CO Lewis bases

Abstract

Unconventional π-hole interactions of tetrel-bearing molecules (TO₂ where T = Ge and Sn) with multiple CO Lewis bases were investigated and comparatively addressed with the aerogen analogs (ZF₂ where Z = Kr and Xe) using ab initio calculations. Toward elucidating the occurrence of π-hole interactions, the TO₂∙∙∙ and ZF₂∙∙∙(CO)_n complexes (n = 1–5) were examined. From the point-of-charge (PoC) calculations, stabilization energies were noticed for all TO₂∙∙∙ and ZF₂∙∙∙PoC systems, ensuring the potential of TO₂ and ZF₂ molecules to participate in π-hole interactions from the electrostatic perspective. From energy calculations, negative interaction energy (E_int) values were observed for all optimized TO₂∙∙∙ and ZF₂∙∙∙(CO)_n complexes with values up to −15.19 kcal/mol. Additionally, negative E_int values were observed to enhance in the order of TO₂/ZF₂∙∙∙(CO)₁ < (CO)₂ < (CO)₃ < (CO)₄ < (CO)₅ complexes. Notably, more negative E_int values were observed for tetrel-bearing complexes than aerogen analogs, outlining the higher favorability of TO₂ molecules to engage in π-hole interactions. From the quantum theory of atoms in molecules and noncovalent interaction index analyses, the favorable nature of the investigated interactions was elucidated. Based on FMOs results, changes in molecular orbital distributions were observed after the interaction with multiple CO LBs, demonstrating the favorability of π-hole interactions within TO₂∙∙∙ and ZF₂∙∙∙(CO)_n complexes. Subsequently, alterations in the calculated electronic parameters were observed following the interaction with CO LBs, outlining the occurrence of π-hole interactions within TO₂∙∙∙ and ZF₂∙∙∙(CO)_n complexes. Such π-hole interactions would be underpinning for the forthcoming studies relevant to supramolecular chemistry and crystal engineering fields.