Unveiling the Nature and Strength of Selenium-Centered Chalcogen Bonds in Binary Complexes of SeO with Oxygen-/Sulfur-Containing Lewis Bases: Insights from Theoretical Calculations.

Among various non-covalent interactions, selenium-centered chalcogen bonds (SeChBs) have garnered considerable attention in recent years as a result of their important contributions to crystal engineering, organocatalysis, molecular recognition, materials science, and biological systems. Herein, we systematically investigated π-hole-type SeO/S ChBs in the binary complexes of SeO with a series of O-/S-containing Lewis bases by means of high-level ab initio computations. The results demonstrate that there exists an attractive interaction between the Se atom of SeO and the O/S atom of Lewis bases. The interaction energies computed at the MP2/aug-cc-pVTZ level range from -4.68 kcal/mol to -10.83 kcal/mol for the SeO chalcogen-bonded complexes and vary between -3.53 kcal/mol and -13.77 kcal/mol for the SeS chalcogen-bonded complexes. The SeO/S ChBs exhibit a relatively short binding distance in comparison to the sum of the van der Waals radii of two chalcogen atoms. The SeO/S ChBs in all of the studied complexes show significant strength and a closed-shell nature, with a partially covalent character in most cases. Furthermore, the strength of these SeO/S ChBs generally surpasses that of the C/O-HO hydrogen bonds within the same complex. It should be noted that additional C/O-HO interactions have a large effect on the geometric structures and strength of SeOS ChBs. Two subunits are connected together mainly via the orbital interaction between the lone pair of O/S atoms in the Lewis bases and the BD*(OSe) anti-bonding orbital of SeO, except for the SeOHCSOH complex. The electrostatic component emerges as the largest attractive contributor for stabilizing the examined complexes, with significant contributions from induction and dispersion components as well.