One mole equivalent of SO2 reversibly reacts with [N(CH3)(4)](2)SO4(s) to give [N(CH3)(4)](2)S2O6(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)(2)SO2 center dot SO2 (2) were isolated from solutions of [N(CH3)(4)](2)SO4 in liquid SO2. The X-ray structure showed that 2 contained the [(O2SO)(2)SO2](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.