Are halide...halide contacts a feature of rock-salts only?

The electron density distribution function in the crystalline hydroxylammonium chloride obtained using the high-resolution X-ray diffraction technique was analyzed by means of Bader's "atoms in molecule" theory. The anion-anion interactions in the crystal of this ionic material were examined and the energy of the Cl-...Cl- contacts was estimated on the basis of the experimental data. The results obtained coincide well with the theoretical calculations and the X-ray diffraction data for the rock-salts. The existence of such type of interactions was shown to be not the unique feature of inorganic salts with point charge cations.