Effect of substitution on the bonding in He dimer confined within dodecahedrane: A computational study

Abstract

The effect of substitution in the dodecahedrane (C₂₀ H₂₀ ) cage on bonding in the confined He dimer is analyzed. The HeHe distances inside the halogenated dodecahedrane C₂₀ X₂₀ (X = FBr) cages are found to be less than half of that in the free He dimer. Comparing the equilibrium structure of He₂ @C₂₀ H₂₀ with He₂ @C₂₀ X₂₀ at ωB97XD/def2-TZVPP level, it is found that the He-He distances are relatively larger in the latter cases indicating the influence of halogen groups on the interaction between the cage and the trapped He pair. The viability of the He₂ @C₂₀ X₂₀ complexes is reflected in the presence of a very high activation energy barrier against the thermochemically feasible dissociation process producing free He₂ and C₂₀ X₂₀ . Quantum theory of atoms in molecules (QTAIM) approach reveals a partial covalent interaction between He pair.

Keywords: QTAIM; encapsulated complexes; energy decomposition analysis; non-covalent interaction; structure and stability.