The structure of hydroxylammonium chloride, NH₃OHCl, and hydroxylammonium bromide, NH₃OHBr

Hydroxylammonium chloride, NH₃OHCl, and hydroxylammonium bromide, NH₃OHBr, are isomorphous and belong to the space group C_2h⁵-P 2₁/c. The unit cell, which contains 4NH₃OHX, has the following dimensions: NH₃OHCl : a = 6.95 A., b = 5.95 A., c = 7.70 A., [beta] = 120.8°, NH₃OHBr: a = 7.29 A., b = 6.13 A., c = 8.04 A., [beta] = 120.8°. The nitrogen and oxygen atoms and the halogen ions occupy general positions 4(e). The parameters have been determined. All these atoms and ions are situated close to the planes (¼, y, z) and (¾, y, z). The distance between the nitrogen and oxygen atoms of the same NH₃OH⁺ group is 1.45 A.