The Crystal Structure of Hydrazinium Dichloride, N2H6Cl2

Accurate values of the two parameters in the structure of crystalline hydrazinium dichloride have been determined by the x‐ray diffraction method, with the use of one and two dimensional Fourier syntheses. The N–N separation in this crystal is 1.42A, and is equal to that in hydrazinium difluoride. This N–N distance is 0.05A shorter than in gaseous hydrazine. Each chloride ion forms hydrogen bonds with three nitrogen atoms, the structure consisting of a three dimensional network of $\mathrm{N}–\mathrm{H}\mathrm{···}\mathrm{Cl}$ bonds. The angle $\mathrm{N}–\mathrm{N}–\mathrm{H}\mathrm{···}\mathrm{Cl}$ is 100°. The configuration of the N₂H₆⁺⁺ ions is trans. The differences between this structure and that of hydrazinium difluoride probably arise from the greater coordinating ability of the chloride ion as compared with that of the fluoride ion. The shortening of the N–N distance may be caused in part by the formal charges on the nitrogen atoms, although it seems certain that this formal charge effect is not of general validity.