Absorption spectra for 2, 3-diaryl-2, 3-diazabicyclo [2.2. 2] octane radical cations (2 (X)•+) and for their monoaryl analogues 2-tert-butyl-3-aryl-2, 3-diazabicyclo [2.2. 2] octane radical cations (1 (X)•+) having para chloro, bromo, iodo, cyano, phenyl, and nitro substituents are reported and compared with those for the previously reported 1-and 2 (H)•+ and 1-and 2 (OMe)•+. The calculated geometries and optical absorption spectra for 2 (Cl)•+ ...