Fig. 4: Interaction of the nitrosonium cation with xFB solvents.

A Molecular structure of the cation in solid [NO(2FB)]⁺[pf]⁻, color code: fluorine—green, oxygen—red, nitrogen—blue, carbon—gray, hydrogen—light gray, anion omitted for clarity, thermal ellipsoids set at 50% probability. B ATR-IR spectra of the solid residues obtained from evaporated solutions of NO⁺[pf]⁻ in xFB (x = 1–6) between 1900 and 2400 cm⁻¹. The spectra from 4FB to 6FB are multiplied by the factor 5, due to the low intensity of the NO band of non-coordinated NO⁺ (calc. at: 28 km mol⁻¹) in comparison to the intensities of the NO bands in the Wheland complexes (calc. at: >1000 km mol⁻¹). C The shape of the deformation density Δρ₍₁₎ corresponding to ΔE_orb(1) (charge flow: red → blue) and the participating fragment orbitals of NO⁺ and 2FB at the BP86(D3BJ)/TZ2P level. The eigenvalue |v₁ | gives the amount of the charge migration in e⁻. D EDA-NOCV results for [(xFB)NO]⁺ complexes using NO⁺ and xFB as interacting fragments at the BP86(D3BJ)/TZ2P level given in kJ mol⁻¹. E Photo of the solutions of NO⁺[pf]⁻ in xFB (x = 1–6) at a concentration of 1 mm. Note the decreasing color intensity with increasing degree of fluorination of xFB.