The basic species in liquid HF is the fl uoride ion or the solvated fl uoride ion, HF 2 . As in the case
of water in which OH forms hydroxo complexes, fl uoride ion forms complexes in liquid HF. This
behavior gives rise to amphoterism with metals ions such as Zn 2 and Al 3 . In the case of Al 3 , AlF 3 is
relatively insoluble in liquid HF so the amphoteric behavior can be shown as follows.