Electronic Structure-Based Design Rules for Noble Gas Complexes

Abstract

The formation of compounds containing noble gases continues to challenge conventional chemical intuition and remains an active area of both experimental and theoretical research. In this study, we present a systematic computational investigation aimed at establishing a predictive criterion for the formation and thermodynamic stability of noble gas-containing compounds, focusing primarily on non-inserted species. Inspired by Bartlett's seminal idea linking noble gas ionization energies to reactivity, we propose an extended model that also considers the electronic affinities of interacting fragments.Using Koopmans' theorem, we define a simple electronic descriptor, Δ₂ = E^Ng_HOMO – E^Fragment_LUMO, which correlates strongly with dissociation free energies computed at the CCSD(T)/def2-TZVP level for a diverse set of 192 diatomic and polyatomic complexes. Our results show that compounds with positive Δ₂ values are thermodynamically stable, while systems with moderately negative Δ₂ values (-100 to -200 kcal•mol⁻¹) may be metastable under low-temperature conditions. The descriptor remains applicable to noble gas interactions with polyatomic electron-deficient fragments, with stability trends rationalized via Hoffmann's isolobal principle. As a case study, we demonstrate that the recently observed ArBO⁺ complex falls within the predicted stability window, validating the utility of the model. This work offers a simple and quantitative design rule for anticipating noble gas compound stability and provides a theoretical foundation to guide future experimental discoveries in noble gas chemistry.