Diiso­propyl­ammonium chloride hemihydrate, a combined single-crystal and powder diffraction study

By the reaction of diiso­propyl­amine (dip) with hydro­chloric acid and crystallization at room temperature, dipHCl, known from the literature, and the corresponding hemihydrate, C₆H₁₆N⁺·Cl⁻·0.5H₂O or dipHCl·0.5H₂O, have been obtained. By using a new humidity chamber for the powder diffraction study it has been proven that dipHCl reacts via a solid-solid phase transition to give dipHCl·0.5H₂O on increasing the relative humidity of the sample atmosphere. The cations and anions are connected by hydrogen bonds to form chains along the crystallographic [100] direction. The extended polymeric zigzag chains form layers in the ac plane, separated by water mol­ecules. The cations and water molecules lie on crystallographic twofold rotation axes.