Acta Cryst. (2014). C70, 220-224 [ doi:10.1107/S2053229614000825 ]
Synopsis: The monohydrate chloride and bromide salts of theophylline are mutually isostructural, with the cations and anions lying on crystallographic mirror planes (Z' = ). The BF4 salt structure is based on planar hydrogen-bonded theopylline cation dimers, with the anions interacting with the dimers in a pendant fashion. The anhydrous chloride salt structure has Z' = 2 and forms one-dimensional chains of cations and anions propagating parallel to the crystallographic c direction.
Formula: C7H9N4O2+·BF4-, C7H9N4O2+·Cl-, C7H9N4O2+·Cl-·H2O and C7H9N4O2+·Br-·H2O
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