From Corannulene to Indacenopicene: Effect of Carbon Framework Topology on Aromaticity and Reduction Limits

Abstract

The electronic structure, reduction limits, and coordination abilities of a bowl-shaped polycyclic aromatic hydrocarbon, indacenopicene (C26H12, 1), have been investigated for the first time using a combination of theoretical and experimental tools. A direct comparison with the prototypical corannulene bowl (C20H10, 2) revealed the effects of carbon framework topology and symmetry change on the electronic properties and aromaticity of indacenopicene. The accessibility of two reduction steps for 1 was predicted theoretically and then confirmed experimentally. Two reversible one-electron reduction processes with the formal reduction potentials at −1.92 and −2.29 V vs Fc+/0 were detected by cyclic voltammetry measurements, demonstrating the stability of the corresponding mono- and dianionic states of 1. The products of the doubly reduced indacenopicene have been isolated as rubidium and cesium salts and fully characterized. Their X-ray diffraction study revealed the formation of tetranuclear organometallic b...