Synthesis\nof [N(CH₃)₄]₂O₃SOSO₂(s) and [N(CH₃)₄]₂[(O₂SO)₂SO₂]·SO₂(s) Containing\n(SO₄)(SO₂)_<i>x</i>^2– <i>x</i> = 1, 2, Members\nof a New Class of Sulfur Oxydianions

Abstract

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