Tetraperchloratoaluminates are salts of the tetraperchloratoaluminate anion, [Al(ClO4)4]−. The anion contains aluminium tetrahedrally surrounded by four perchlorate groups. The perchlorate is covalently bonded to the aluminium, but perchlorate is much more well known as an ion. The covalent bond to aluminium distorts the perchlorate and renders it unstable.[1]
Related chemicals are the haloperchloroatoaluminates, where there is one perchloro group attached to aluminium, and three halogens such as chlorine (chloroperchloroatoaluminates) or bromine (bromoperchloroatoaluminates).[2]
complex
was invoked but never defined (see the help page).