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Spectroscopic Determination of an Anion−π Bond Strength
- Anstöter, Cate S., Rogers, Joshua P., Verlet, Jan R. R.
- Journal of the American Chemical Society 2019 v.141 no.15 pp. 6132-6135
- electrostatic interactions, gases, spectral analysis, spectroscopy
- The anion−π bond has emerged as an important nonvalence interaction in supramolecular and biological structure. Although recognized as a strong noncovalent interaction, driven by electrostatic charge-quadrupole moment and correlation interactions, benchmark experimental and computational studies on the intrinsic anion−π bond strength are scarce. Here, we present a gas-phase photoelectron spectroscopic study on the archetypical iodide-hexafluorobenzene anion−π bonded complex. In combination with high-level electronic structure calculations, the anion−π bond strength is found to be 0.53 eV (51 kJ mol–¹). The interaction arises for a large part from correlation forces (∼40%), with electrostatic quadrupole-anion and polarization making up most of the remainder.