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
Anna Caria, Stéphane A. Baudron, M. Carla Aragoni, Vito Lippolis, Anna Pintus, Enrico Podda, Massimiliano ArcaABSTRACT
The reactivity of tetra(pyridin‐4‐ylthio)tetrathiafulvalene ( L 1 ) toward dihalogens (Br 2 , I 2 )/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 L 1 with I 2 yielded a 1:4 adduct L 1 ·4I 2 ( 1 ), featuring four independent N···I─I interactions within a single polytopic scaffold. Reactions of L 1 with Br 2 , ICl, and IBr afforded ionic species ( 2–6 ), containing the protonated donor counterbalanced by discrete tri(inter)halide anions such as [Br 3 ] − , [ICl 2 ] − , and [IBr 2 ] − . These compounds showed diverse supramolecular cage‐like architectures, often involving hydrogen‐bonded networks. [H 4 L 1 ]( L 1 )[IBr 2 ] 4 ·2CH 3 CN·2.4CHCl 3 ( 4 ) contains a tetracationic capsule [(H 4 L 1 )( L 1 )] 4+ stabilized by N–H···N HBs and templated at a [IBr 2 ] − guest. Both the N···I─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 [(H 4 L 1 )( L 1 )(IBr 2 )] 3+ , and reproduction of the observed structural trends, highlighting the continuous nature of covalent‐to‐electrostatic interactions in apparently different three‐body systems.