Redetermination of 1,3-diammonio-1,2,3-tride­oxy-cis-inositol dichloride

The crystal structure of the title compound, C₆H₁₆N₂O₃²⁺·2Cl⁻, has been reported previously by Palm [Acta Cryst. (1967), 22, 209–216] from Weisenberg camera data, with R1 = 10.5%, isotropic refinement of non-H atoms and H atoms not located. We remeasured a data set of the title compound and present a more precise structure determination. The asymmetric unit contains two unique 1,3-diammonio-1,2,3-tride­oxy-cis-inositol cations and four Cl⁻ counter-ions. The cyclo­hexane rings of both inositol cations adopt chair conformations with two axial hy­droxy groups. An extended network of hydrogen bonds is formed. The four chloride counter ions are hydrogen bonded to the hydroxy and ammonium groups of the cations by N—H...Cl and O—H...Cl interactions. The cations are aligned into wavy layers by cation...cation interactions of the form N—H...O(ax), N—H...O(eq) and O(ax)—H...O(eq). Intramolecular hydrogen bonding between the axial hydroxy groups is, however, not observed.