Abstract
Interactions of hypervalent IF(5) and XeF(4)O molecules within the square pyramidal geometry via σ-hole site with Lewis bases (LB = NH(3) 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 XeF(4)O⋯LB complexes, compared to IF(5)⋯LB complexes, along with nominal deformation energies for all complexes. Turning to IF(5)⋯ and XeF(4)O⋯X(-) complexes, E (bind) demonstrated the proficiency of the latter complexes, which was in synchronic with the V (s,max) claims. On the contrary, IF(5)⋯X(-) complexes demonstrated higher negative E (int) values in comparison to XeF(4)O⋯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: IF(5)/XeF(4)O⋯NCH < ⋯NH(3) < ⋯I(-) < ⋯Br(-) < ⋯Cl(-) < ⋯F(-). Quantum theory of atoms in molecules/noncovalent interactions index observations affirmed that the interactions of IF(5)/XeF(4)O molecules via σ-hole site with NH(3) and NCH were characterized with open- and closed-shell nature, respectively, while the IF(5)/XeF(4)O⋯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.