2,2′:6′,2"-terpyridine as monodentate ligand:: Halogen bonding driven formation of discrete 2:1 aggregates with 1,2,4,5-tetrafluoro-3,6-diiodobenzene

2,2':6',2"-Terpyridine (1) is a well-known electron donor module in metal coordination chemistry and typically works as a tridentate ligand. Here it is shown that 1 can also work as electron donor towards iodoperfluorocarbons both in solution and in the solid phase. Halogen-bonded supramolecular systems are thus obtained. Specifically, terpyridine 1 self-assembles with 1,2,4,5-tetrafluoro- 3,6-diiodobenzene (2) and affords the trimeric adduct 3, which is stable and crystalline in the air at room temperature. Single crystal X-ray analysis shows how in adduct 3 both iodine atoms of one molecule of 2 are halogen-bonded to the nitrogen atoms of external pyridine rings of two molecules of 1 that act as monodentate electron donors.