Low-temperature X-ray structures of the following di(4-X-benzenesulfonyl)amines, HN(SO2-C6H4-X)2, are compared in order to study the effects of the 4-substituents on the molecular packings: X = F (1, monoclinic, C2/c, Z′ = 1), X = Cl (2, monoclinic, C2/c, Z′ = 1/2, N-H bonds lying on twofold rotation axes), X = Me (3, orthorhombic, Pbca, Z′ = 1), X = Br (4A, monoclinic, P21/c, Z′ = 1), X = Br (4B, monoclinic, P21/c, Z′ = 2). As a common feature, the molecules of the halogen compounds, including two polymorphs of 4, are associated into catemers by strong hydrogen bonds of the type N-H···O in 1, 4A and 4B or N-H(···O)2 in 2. These molecular chains are assembled in the crystal structures via different packing modes, which underline the well-known correlation between the atomic number of halogen atoms and their propensity to form halogen bonds. Thus, the structure of 1 is devoid of short C-F···O/N contacts, but close F···F contacts are tolerated, whereas in 2 each catemer is connected to four parallel congeners by long and bifurcated C-Cl(···O)2 bonds, and both polymorphs of 4 display layers in which the molecules are connected by N-H···O bonds in one and by relatively short and approximately linear C-Br···O interactions in the other dimension. Despite the alleged steric equivalence of methyl and chloro substituents (“chloro-methyl exchange rule”), the packing architecture of the methyl compound 3 is not related to any of the preceding structures. In this case, the N-H···O bonding leads to centrosymmetric cyclodimers, which pack in such a way that each methyl group is located between two oxygen atoms and above the face of an aromatic ring in a topology consistent with C-H···O and C-H···C(π) bonding. All the structures are pervaded by weak Car-H···O hydrogen bonds; moreover, 1 displays a short C-H···F hydrogen bond and a C-F···C(π) interaction, and π-stacking of aromatic rings is observed in 1, 3 and 4B
(E)-2-Methyl-6-{[(5-methylpyridin-2-yl)imino]methyl}phenol
