DFT study of structure and binding energies of Fe-corannulene complex

Density functional theory (DFT) based theoretical calculations are performed to identify the ground-state geometries, the spin multiplicities, and the relevant energetics of neutral and positively charged Fe-corannulene complexes. Our calculations show that the on-top site of the six-membered ring (eta(6)) of corannulene molecule is the most preferred binding site for both Fe atom and Fe(+) ion. The electrostatic potential (ESP) surface picture is employed to explain the preference of the eta(6)- over the eta(5)-binding site (on-top site of central pentagon) of corannulene. Though in both neutral and cationic species the eta(6)-site is the most preferred binding site, the ground-state geometries of these complexes are different. The Fe(+) cation prefers to bind to the convex face of the corannulene, whereas the neutral Fe atom prefers slightly the concave to the convex face. The ionization-induced structural changes are reflected in the large energy difference between the vertical and adiabatic ionization potential values. We also show that the dissociation of Fe(+)-corannulene complex to corannulene + Fe(+) is just as likely as that to Fe + (corannulene)(+).