Isomorphous Structures of Iron(II) Clathrochelates Featuring Terminal σ-Hole Donor Sites and Exhibiting the Cl/Br/I/S Quadruple Heteroisostructural Exchange

Upon crystallization from benzene–dichloromethane mixtures, the clathrochelates [Fe{FB[(–ON═C(Ph)C(Ph)═NO–)2(–ON═C(R)C(R)═NO–)]BF}] (R = Cl 1, Br 2, I 3; RR = SCH2CH2S 4) release as isomorphous cocrystals (1–4)·2PhH, which were studied by X-ray diffractometry (XRD). In their XRD structures, the short contacts of C–X···F–B were attributed to a halogen bond (HaB; X = Cl, Br, I) and a chalcogen bond (ChB; X = S), both occurring in nearly the same environment. This system presents a unique case of quadruple heteroisostructural exchange involving atoms from different groups of the periodic table. These atoms are involved in two distinct types of noncovalent interactions, namely, HaB and ChB. The XRD data were used to compare the geometrical parameters and computationally analyze the nature of HaB and ChB. The σ-holes on the halogen and sulfur atoms were found to be directed in the same way. This result is relevant to crystal engineering because it opens up a route to the targeted design of analogous supramolecular architectures via interchangeable HaB and ChB.