An IQA/QTAIM Approach to the Chalcogen Bond

Communications in Computational Chemistry. 2026. Vol. 8. No. 2. P. 203–210.

Novikov A.

Chalcogen bonds (ChBs) are often interpreted as 𝜎-hole driven electrostatic interactions between a chalcogen atom and a Lewis base, yet their covalent character remains under active discussion. Here, we present a real-space, reference-free study of prototypical X2Ch···X– complexes (X = F, Cl; Ch = O, S) using the Interacting Quantum Atoms (IQA) energy decomposition within the framework of the Quantum Theory of Atoms in Molecules. Molecular electrostatic potential, Laplacian, and electron localization function analyses confirm the presence and modulation of 𝜎-holes upon complexation, while IQA formation energies reveal a broad stability range, from weakly bound Cl2O···Cl– to strongly stabilized F2S···F– systems. Energy decomposition shows that exchange–correlation contributions systematically dominate fragment interaction energies, whereas the classical Coulomb term can be secondary or even destabilizing, ruling out a purely electrostatic description. Atomic-level analysis further demonstrates that stabilization arises from a collective interplay between the direct Ch···X– contact and significant X2···X– contributions, evidencing delocalized electron sharing beyond the donor–acceptor axis. Overall, these results provide an orbital-invariant and quantitatively rigorous picture of ChBs, highlighting their substantial covalent character and many-atom cooperative nature.

Keywords: квантовая химия, Chemistry

Publication based on the results of: Металлизированные фталоцианины как высокоэффективные фотосенсибилизаторы в фототерапии рака (2027)