3,6-Diazaoctane-1,8-diaminium diiodide

Abstract

The asymmetric unit of the title salt, C6H20N4²⁺·2I⁻, comprises half a 3,6-diaza­octane-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 inter­molecular inter­actions: two H atoms of the ammonium group form inter­actions with two I⁻ anions and the H atom of the secondary amine forms a weak inter­action 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.