Results of the Dirac-Slater discrete-variational calculations are presented for the group 6 dioxydichlorides, MO(2)Cl(2) (M = Cr, Mo, W, and element 106, Sg). Estimates of the bond strengths and stability toward thermal decomposition have shown single molecules of O2Cl2 to be as stable as those of MoO2Cl2. Calculated energies of electronic charge-transfer transitions proved to be lower than those for WO2Cl2. The stability of the +6 oxidation state is shown to decrease in going from the W to Sg compound.