Synthesis of [N(CH3)4]2O3SOSO2(s) and [N(CH3)4]2[(O2SO)2SO2]·SO2(s) Containing (SO4)(SO2) x 2– x = 1, 2, Members of a New Class of Sulfur Oxydianions

One mole equivalent of SO2 reversibly reacts with [N(CH3)4]2SO4(s) to give [N(CH3)4]2S2O6(s) (1) containing the [O3SOSO2]2–, shown by Raman and IR to be an isomer of the [O3SSO3]2– dianion. The experimental and calculated (B3PW91/6-311+G(3df)) vibrational spectra are in excellent agreement, and the IR spectrum is similar to that of the isoelectronic O3ClOClO2. Crystals of [N(CH3)4]2­(O2SO)2SO2·SO2 (2) were isolated from solutions of [N(CH3)4]2SO4 in liquid SO2. The X-ray structure showed that 2 contained the [(O2SO)2SO2]2– dianion. The characterized N(CH3)4 + salts 1 and 2 are the first two members of the (SO4)(SO2) x 2– class of sulfur oxydianions analogous to the well-known small cation salts of the SO4(SO3) x 2– polysulfates.