Metal ammine complex
In coordination chemistry, metal ammine complexes are metal complexes containing at least one ammonia () ligand. "Ammine" is spelled this way due to historical reasons; 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. Ammine complexes played a major role in the development of coordination chemistry, specifically determination of the stereochemistry and structure. They are easily prepared, and the metal-nitrogen ratio can be determined by elemental analysis. Through studies mainly on the ammine complexes, Alfred Werner developed his Nobel Prize-winning concept of the structure of coordination compounds (see Figure). One of the first ammine complexes to be described was Magnus' green salt, which consists of the platinum tetrammine complex . Ammonia is a Lewis base and a "pure" sigma donor. It is also compact such that steric effects are negligible. These factors simplify interpretation of structural and spectroscopic results.The Co–N distances in complexes have been examined closely by X-ray crystallography. Homoleptic poly(ammine) complexes are known for many of the transition metals. Most often, they have the formula where n = 2, 3, and even 4 (M = Pt). Platinum group metals form diverse ammine complexes. Pentaamine(dinitrogen)ruthenium(II) and the Creutz–Taube complex are well-studied examples of historic significance. The complex cis-, under the name Cisplatin, is an important anticancer drug. Pentamminerhodium chloride () is an intermediate in the purification of rhodium from its ores. File:Carboplatin-skeletal.svg|[[Carboplatin]], a widely used anticancer drug. File:(RhA5Cl)Cl2.png|[[Pentamminerhodium chloride]], the dichloride salt of a pentammine halide complex. File:RuA5N2.png|[[Pentaamine(dinitrogen)ruthenium(II) chloride|Pentaamine(dinitrogen)ruthenium(II)]], the first [[metal dinitrogen complex]].
