Difluorine complex

A difluorine complex is a molecular coordination complex involving a difluorine (F₂) group as a ligand. The first example was gold heptafluoride (AuF₇).^[1] Instead of being a gold(VII) compound, with all five fluorine atoms equally bonded to the central gold atom, the structure is an adduct of gold(V) fluoride (AuF₅) and F₂. This conclusion has been repeatedly supported by calculations. Unlike dihydrogen complexes, which feature a "side-on" bonding of the hydrogen group (η²-H₂), difluorine complexes feature "end-on" bonding (η¹-F₂).^[2]