Metallate is the name given to any complex anion containing a metal ligated to several atoms or small groups. The spelling metalate is almost as common.
Typically, the metal will be one of the transition elements and the ligand will be oxygen or another chalcogenide or a cyanide group (though others are known). The chalcogenide metallates are known as oxometallates, thiometallates, selenometallates and tellurometallates; the cyanide metallates are known as cyanometallates.
Oxometallates include permanganate (MnO4−), chromate (CrO42-) and vanadate (VO3− or VO43-).
Thiometallates include tetrathiovanadate (VS43-), tetrathiomolybdate (MoS42-), tetrathiotungstate (WS42-) and similar ions.
Cyanometallates include ferricyanide and ferrocyanide.
Metallate is also used as a verb by bioinorganic chemistry to describe the act of adding metal atoms or ions to a site (synthetic ligand or protein.)