Theoretical insights into two types of Se···N Chalcogen Bonds between phenylselenium halides (PhSeX, X = F, Cl, Br, I) and pyridine: perpendicular versus linear binding modes via tunable σ-holes

Abstract

Context

In this work, the Se···N chalcogen-bonding interactions in pyridine-phenylselenium halides (C₅H₅N-PhSeX, X = F, Cl, Br, and I) complexes were systematically investigated at the ωB97XD/def2-TZVPD theoretical level. Two typical structural configurations, namely perpendicular and linear orientations, were identified for all studied complexes. The calculated binding energies suggest that the linear-oriented systems exhibit remarkably stronger intermolecular interactions (− 6 to − 12 kcal/mol) than their perpendicular counterparts (− 2 to − 4 kcal/mol). For the perpendicular-oriented structures dominated by chalcogen-bonding with secondary hydrogen-bonding interactions, the intermolecular interaction strength increases in the order F > I > Br > Cl. In contrast, the interaction strength of linear-oriented chalcogen-bonding complexes follows the sequence of F > Cl > Br > I. Energy component analysis indicates that both electrostatic and dispersion contributions dominate the attractive forces in perpendicular chalcogen-bonded systems. By comparison, the stabilization of linear complexes is predominantly governed by electrostatic interactions.

Methods

Geometry optimizations of all complexes and the corresponding monomers were carried out at the ωB97XD/def2-TZVPD level. The nature of the intermolecular interactions was then characterized by NBO population analysis, QTAIM (AIM), and IRI analyses.In addition,the interaction energies of the two types of chalcogen-bonded complexes were further decomposed by means of symmetry-adapted perturbation theory (SAPT).