3,6-Diaza-octane-1,8-diaminium diiodide

The asymmetric unit of the title salt, C6H20N4 ²⁺·2I ^-, comprises half a 3,6-diaza-octane-1,8-diaminium dication plus an I^- anion. The dications are symmetrical and lie across crystallographic centres of inversion. In the crystal, the ions form a network involving mainly weak N-H⋯I inter-molecular inter-actions: two H atoms of the ammonium group form inter-actions with two I^- anions and the H atom of the secondary amine forms a weak inter-action with a third I^- cation. The third ammonium H atom is hydrogen bonded to a secondary amine of an adjacent cation. The backbone of the cation does not form a uniformly trans chain, but is kinked [C-N-C-C torsion angle = 71.5 (2)°], probably to accommodate the direct hydrogen bond between the ammonium group and the secondary amine in an adjacent cation.