Theoretical Study of Aromaticity of Corannulene and Related π-Bowls: Effect of Carbon Framework Topology and Substitutions

Corannulene, the smallest curved fragment of C₆₀-fullerence, triggered an extensive theoretical and experimental exploration of its fascinating features of oxidation, reduction, and coordination in organometallics and materials chemistry. Currently, many efforts have been directed to corannulene functionalization and synthesis of topology related π-bowls.

In the first part of the presentation, Li will talk about the exceptional stability of hub-site functionalized corannulene cation [CH₃-hub-C₂₀H₁₀]⁺, successfully synthesized in 2011. To explain the stability of this interior addition product, the researchers undertook a comprehensive theoretical study of aromaticity changes from neutral corannulene to the functionalized cations. The products functionalized at the exterior part were also studied in order to explain their absence in experiment. Further investigation included the influence of lengthening of alkyl groups and other stable cationic groups such as iPr and tBu on stability and electronic structure of the target functionalized cations.

In the second part, Li will introduce the recently developed larger π-bowl molecule indacenopicene C₂₆H₁₂. Intrigued by the unique structure of this carbon-rich bowl having an extended π-surface and different symmetry (C_s) compared to the prototypical corannulene, the researchers performed detailed calculations of the electronic structure and aromaticity. The molecular orbital diagrams of their neutral species were also investigated in detail in order to reveal the effect of carbon framework topology on the reduction limit.

Finally, stepping aside from the buckybowl chemistry, Li will briefly present recent results of computational exploration of the reaction mechanism for trimerization of N-heterocyclic silylene. For such a trimer, the zwitterionic state was found to be dominant.