Hydrogen Bond Studies. XXXVII. The Crystal Structure of Sulfuric Acid Dihydrate (H3O+)2SO42−

The crystal structure of H₂SO₄·2H₂O has been determined from three‐dimensional single‐crystal x‐ray data recorded at −190°C. The crystals are monoclinic, space group $\text{C2\hspace{0.17em}/\hspace{0.17em}c}$ , with 12 formula units in a cell with the dimensions: $\text{a\hspace{0.17em}=\hspace{0.17em}13.008}$ , $\text{b\hspace{0.17em}=\hspace{0.17em}7.979}$ , $\text{c\hspace{0.17em}=\hspace{0.17em}14.881}$ , and $\text{β\hspace{0.17em}=\hspace{0.17em}101.60°}$ . The structure consists of H₃O⁺ and SO₄²⁻ ions. Each of the three independent H₃O⁺ ions is hydrogen bonded to three different SO₄²⁻ ions (0···0 distances, 2.520–2.590 Å) is such a way that a three‐dimensional hydrogen‐bond pattern is formed. The average S–O distance in the sulfate ion is 1.474 Å.