Low-temperature X-ray structures and crystal packing arrangements are presented for di(4-iodobenzenesulfonyl)amine (4, monoclinic, P2 1 /c, Z ' = 1, isostructural to a previously described dimorph of the corresponding bromo homologue), 2,4-dimethylpyridinium di(4- iodobenzenesulfonyl)amide (5, monoclinic, P2 1 /n, Z ' = 1, isostructural to the corresponding bromo compound), and 3-methylpyridinium di(4-iodobenzenesulfonyl)amide (6, orthorhombic, Pna2 1 , Z '= 1). The packing of 4 consists of non-lamellar layers, in which the molecules are connected by N-H···O hydrogen bonds in one and by I δ+ ···O δ− interactions in the other dimension. Structure 5 involves strands of formula units, whereby the anions form catemers via I δ+ ···O δ− interactions and the cations are isotactically connected to the anion backbone by an N + - H(···O) 2 three-centre bond. Short I···I contacts are absent from structures 4 and 5. In contrast, structure 6 displays lamellar layers comprising an inner lamella of cations and N(SO 2 ) 2 groups connected by an N + - H···N − two-centre bond, and peripheral regions of 4-iodophenyl rings. Thus, the iodine atoms are efficiently shielded from the oxygen atoms, but in appropriate positions to form I δ+ ···I δ− interlayer contacts. Each structure is reinforced by a parallel-displaced π···π stacking arrangement of aromatic rings and an abundance of short C-H···A contacts (A = acceptor).