From Charge‐Transfer Adducts to (Tri)Halide‐Templated Supramolecular Cages: Covalent vs Ionic Products in the Reactions of Pyridin‐4‐ylthio‐Substituted Tetrathiafulvalene With Dihalogens and Interhalogens

The reactivity of tetra(pyridin-4-ylthio)tetrathiafulvalene (L1) toward dihalogens (Br2, I2)/interhalogens (ICl, IBr) was investigated by crystallographic, microanalytical, spectroscopic, and hybrid-DFT approaches. A divergence in reactivity was observed depending on the halogen reagent. The reactions of L1 with I2 yielded a 1:4 adduct L1 & centerdot;4I2 (1), featuring four independent N & centerdot;& centerdot;& centerdot;I & horbar;I interactions within a single polytopic scaffold. Reactions of L1 with Br2, ICl, and IBr afforded ionic species (2-6), containing the protonated donor counterbalanced by discrete tri(inter)halide anions such as [Br3]-, [ICl2]-, and [IBr2]-. These compounds showed diverse supramolecular cage-like architectures, often involving hydrogen-bonded networks. [H4 L1](L1)[IBr2]4 & centerdot;2CH3CN & centerdot;2.4CHCl3 (4) contains a tetracationic capsule [(H4 L1)(L1)]4+ stabilized by N-H & centerdot;& centerdot;& centerdot;N HBs and templated at a [IBr2]- guest. Both the N & centerdot;& centerdot;& centerdot;I & horbar;I fragment in compound 1 and the tri(inter)halides in compounds 2-6 follow a common structural correlation between the normalized bond elongations typical of three-body systems. Hybrid-DFT QTAIM, NBO, Hirshfeld, and Bader charges, along with NCI index calculations allowed to quantify the CT interactions and the extent of ionic/covalent contributions to the HaBs in compound 1, analysis of the anion-cation interactions in the inclusion complex [(H4 L1)(L1)(IBr2)]3+, and reproduction of the observed structural trends, highlighting the continuous nature of covalent-to-electrostatic interactions in apparently different three-body systems.