In this state-of-the-art quantum-chemical investigation we report structures, thermochemical stabilities, Born-Fajans-Haber cycles as well as vibrational data of heterodimeric and homodimeric radical cations of the series [and [Cl 4 ] + . The so far experimentally unknown species [F 4 ] + , [F 2 O 2 ] + and [F 2 Cl 2 ] + are predicted to be thermochemically stable and could be possible targets for gas-phase or matrix-isolation experiments. Furthermore, their stabilities as homodimeric [X 4 ] + or heterodimeric [X 2 Y 2 ] + radical cation salts in the solid state have been estimated by Born-Fajans-Haber cycles.