Cation-π interactions of curved polycyclic systems: M+ (M=Li and Na) ion complexation with buckybowls

B3LYP/6-311+G** calculations on alkali metal ion (Li+ and Na+) complexation with corannulene and sumanene indicate stronger binding compared to [5]-radialene or benzene. The dependence of binding to the convex and concave site is marginal, albeit the preference was consistent for convex binding in the range of 1–4 kcal/mol. The bowl-to-bowl inversion barriers are only marginally affected, below 2 kcal/mol, by metal ion complexation.