Experimental

R factor = 0.035; wR factor = 0.074; data-to-parameter ratio = 18.3. The asymmetric unit of the title compound, C18H16Br4N2O2, comprises half the molecule, which is located adjacent to an inversion centre at the mid-point of the central C—C bond of the butane-1,4-diamine segment. There are two intra-molecular O—H N hydrogen bonds making S(6) ring motifs. In the crystal, molecules are linked by pairs of weak C—H Br interactions into chains along [101], which include R2 2(8) ring motifs. These chains are further linked by C— H O hydrogen bonds, forming a three-dimensional network. Related literature For standard bond lengths, see: Allen et al., (1987). Fo