Fullerene and corannulene derivatives acting as insulators of Cl− and BeH2

Abstract

The capacity of corannulene and its benzo-derivatives C_xH₁₀ (x = 20–60) as prototypes of non-planar π-aromatic systems which mimic the end of carbon nanotubes to act as insulators between BeH₂ and Cl⁻ chemical entities has been explored by means of M06-2x/cc-pVDZ and M06-2x/6-311+G(d) calculations. For the sake of completeness, the set investigated includes also fullerene, C₆₀. All these aromatic derivatives lead to stable binary complexes either with BeH₂ or halogen (Cl⁻) anions. For BeH₂, however, only the complexes in which the interaction involves the convex face of the aromatic system are stable. No significant changes are observed when the binding energies (BEs) of the BeH₂ complexes are compared to those involving planar aromatic compounds, but the ones involving Cl⁻ with the concave face of the aromatic moiety can be very large, because its curvature favors many contacts of the anion with the carbon atoms of the π-aromatic system. The formation of these binary complexes changes to a large extent the electrostatic potential on the free face of the aromatic system leading to a mutual reinforcement of both interactions, the beryllium bond and the interaction with Cl⁻, when the ternary complexes are formed. As a result, the BEs for the triads are larger than the sum of the BEs of the corresponding binary complexes and the distances between the aromatic subunit and BeH₂ or Cl⁻ become shorter in the triads than in the binary complexes. A MBIE analysis also indicates that the enhanced stability of ternary complexes arises mainly from the reinforcement of the beryllium bonds as well as from the three-body terms. An exploration of all the minima for BeH₂:C₆₀H₁₀:Cl⁻ shows that BeH₂ binds preferentially to the peripheral aromatic rings than those in the more curved region.