Electronic spectra were measured for azidobenzene, 1-azidopyrene, benzenediazonium ion, and 1-pyrenediazonium ion at room temperature, and also for nitrenobenzene and 1- nitrenopyrene at liquid nitrogen temperature. The π-electron structures of these compounds were calculated by the Pariser-Parr-Pople LCAO SCF MO CI method for the closed-shell systems and by the restricted open-shell SCF MO CI method for the open-shell systems. ...