The Radical Anion and Dianion of Benzo[3,4]cyclobuta[1,2- b ]phenazine.

We present the reduction of two azaacenes (a benzo-[3,4]cyclobuta[1,2-]phenazine and a benzo[3,4]cyclobuta[1,2-]naphtho[2,3-]phenazine derivative), featuring a single cyclobutadiene unit, to their radical anions and dianions. The reduced species were produced using potassium naphthalenide in the presence of 18-crown-6 in THF. Crystal structures of the reduced representatives were obtained and their optoelectronic properties evaluated. Charging these 4 Hückel systems gives dianionic 4 + 2 π-electron systems with increased antiaromaticity, according to NICS(1.7) calculations, featuring unusually red-shifted absorption spectra.