A Stable π-Expanded o-Quinodimethane via the Photochemical Dearomative Cycloaddition of Corannulene with an Isolable Dialkylsilylene

A stable π-expanded o-quinodimethane derivative (2) was synthesized by photochemical dearomative cycloaddition of corannulene with an isolable dialkylsilylene (1) and isolated as a dark blue solid. Compound 2 adopts a very flat bowl shape in contrast to parent corannulene. Structural and spectroscopic characteristics, redox properties, and computational study suggest that 2 has a small but significant diradical character (y0 = 0.11). One-electron reduction of 2 provides the corresponding radical anion as an isolable salt.