Structure of Mg₆SO₂(OH)₁₄ determined by micro single-crystal X-ray diffraction

The structure of hexamagnesium sulfonyl tetradecahydroxide, Mg₆SO₂(OH)₁₄, has been determined with an extremely small single-crystal (ca 0.5 × 100 × 2.5 μm) using synchrotron radiation [1.00 (1) Å]. The crystal is orthorhombic with space group Ccmm (No. 63), a = 15.895 (1), b = 3.105 (1), c = 13.367 (1) Å, V = 659.64 (3) ų and Z = 2. The final R and wR values are 0.073 and 0.083 for 105 crystallographically independent reflections. The structure consists of MO₆ octahedra and SO₄ tetrahedra. The MgO₆ octahedra share their edges to form zigzag sheets parallel to (100). The SO₄ tetrahedron shares two of the O atoms with the MgO₆ octahedra at the turning of the sheet and is statistically located with a probability of 0.5. Fine streaks observed perpendicular to the b* axis on diffraction photographs indicate that the SO₄ tetrahedra are distributed at random along the a and c axes, but alternately along the b axis. All the H atoms are considered to exist in the form of OH groups.

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