Synthesis of 1,2′-Biazulenes by Palladium-Catalyzed Unusual Homocoupling Reaction of 1-Haloazulenes in the Presence of Ferrocene

The synthesis of 1,2′-biazulenes was established by palladium-catalyzed homocoupling reactions of the corresponding 1-haloazulenes in the presence of ferrocene. The optical properties of the novel 1,2′-biazulenes were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behaviors of 1,2′-biazulenes were also examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).