In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia (NH3) ligand. "Ammine" is spelled this way for historical reasons;[1] in contrast, alkyl or aryl bearing ligands are spelt with a single "m". Almost all metal ions bind ammonia as a ligand, but the most prevalent examples of ammine complexes are for Cr(III), Co(III), Ni(II), Cu(II) as well as several platinum group metals.[2]