The crystal structure of hexamethylenediamine and its dihalides. Hexamethylenediamine dihydrobromide

Hexamethylenediamine dihydrobromide, C₆H₁₈N₂Br₂, is monoclinic, space group P2₁/c, with four molecules per unit cell. Only minute needle crystals were available, but the structure factors of the principal zone, (0kl), have been measured. A Patterson analysis determines the positions of the eight bromine atoms in this projection without ambiguity. This is followed by a two-dimensional Fourier synthesis from which the approximate positions of all the atoms can be estimated. The results are consistent with an extended chain structure of normal bond distances (1.4-1.6 A.), and with Br-N distances lying between 3.2 and 3.5 A. These results provide a basis for a more accurate determination of the structure of the isomorphous dihydrochloride.