Tetrameric and Dimeric [N•••I+•••N] Halogen-Bonded Supramolecular Cages

Tripodal N-donor ligands are used to form halogen-bonded assemblies via structurally analogous Ag+-complexes. Selective formation of discrete tetrameric I6L4 and dimeric I3L2 halonium cages, wherein multiple [N center dot center dot center dot I+center dot center dot center dot N] halogen bonds are used in concert, can be achieved by using sterically rigidified cationic tris(1-methyl-1-azonia-4-azabicyclo[2.2.2]octane)-mesitylene ligand, L1(PF6)(3), and flexible ligand 1,3,5-tris(imidazole-1-ylmethyl)-2,4,6-trimethylben-zene, L2, respectively. The iodonium cages, I(6)L1(4)(PF6)(18) and I(3)L2(2)(PF6)(3), were obtained through the [N center dot center dot center dot Ag+center dot center dot center dot N]->[N center dot center dot center dot I+center dot center dot center dot N] cation exchange reaction between the corresponding Ag(6)L1(4)(PF6)(18) and Ag(3)L2(2)(PF6)(3) coordination cages, prepared as intermediates, and I-2. The synthesized metallo- and halonium cages were studied in solution by NMR, in gas phase by ESI-MS and in the solid-state by single crystal X-ray diffraction.