Interactions of hypervalent IF5 and XeF4O molecules via σ-hole site with Lewis bases and anions: a comparative ab initio study

Abstract

Interactions of hypervalent IF₅ and XeF₄O molecules within the square pyramidal geometry via σ-hole site with Lewis bases (LB = NH₃ and NCH) and anions (X⁻ = F⁻, Cl⁻, Br⁻, and I⁻) were comparatively investigated using ab initio methods. The energetic features outlined remarkable interaction (E_int) and binding (E_bind) energies for all complexes aligned from −5.65 to −91.02 kcal mol⁻¹ and from −5.53 to −65.89 kcal mol⁻¹, respectively. More negative E_int and E_bind values were demonstrated for XeF₄O⋯LB complexes, compared to IF₅⋯LB complexes, along with nominal deformation energies for all complexes. Turning to IF₅⋯ and XeF₄O⋯X⁻ complexes, E_bind demonstrated the proficiency of the latter complexes, which was in synchronic with the V_s,max claims. On the contrary, IF₅⋯X⁻ complexes demonstrated higher negative E_int values in comparison to XeF₄O⋯X⁻ complexes, which may be attributed to the considerable favorable deformation energies relevant to the former complexes rather than the latter candidates. Moreover, the E_int and E_bind were disclosed to ameliorate in coincidence with the Lewis basicity strength as follows: IF₅/XeF₄O⋯NCH < ⋯NH₃ < ⋯I⁻ < ⋯Br⁻ < ⋯Cl⁻ < ⋯F⁻. Quantum theory of atoms in molecules/noncovalent interactions index observations affirmed that the interactions of IF₅/XeF₄O molecules via σ-hole site with NH₃ and NCH were characterized with open- and closed-shell nature, respectively, while the IF₅/XeF₄O⋯X⁻ complexes were characterized with the coordinative covalent nature. Symmetry-adapted perturbation theory results pinpointed the predominance of the inspected interactions with the electrostatic forces. The acquired results will be advantageous for the ubiquitous investigation of understanding the impact of geometrical deformation on the interactions of hypervalent molecules and their applications in diverse fields such as materials science and crystal engineering.