Metal ammine complex

"Ammine" is spelled this way for historical reasons;[1] in contrast, alkyl or aryl bearing ligands are spelt with a single "m".

[2] Ammine complexes played a major role in the development of coordination chemistry, specifically determination of the stereochemistry and structure.

Through studies mainly on the ammine complexes, Alfred Werner developed his Nobel Prize-winning concept of the structure of coordination compounds (see Figure).

[6] Ammonia is a pure σ-donor, in the middle of the spectrochemical series, and shows intermediate hard–soft behaviour (see also ECW model[7][8] ).

These factors simplify interpretation of structural and spectroscopic results.The Co–N distances in complexes [M(NH3)6]n+ have been examined repeatedly by X-ray crystallography.

This property is illustrated by the stability of some metal ammine complexes in strong acid solutions.

The deprotonation of cobalt(III) ammine-halide complexes, e.g. [CoCl(NH3)5]2+ labilises the Co–Cl bond, according to the Sn1CB mechanism.

In some separation schemes, palladium is purified by manipulating equilibria involving [Pd(NH3)4]Cl2, [PdCl2(NH3)2], and [Pt(NH3)4][PtCl4] (Magnus's green salt).

In the processing of cellulose, the copper ammine complex known as Schweizer's reagent ([Cu(NH3)4(H2O)2](OH)2) is sometimes used to solubilise the polymer.

Schweizer's reagent is prepared by treating an aqueous solutions of copper(II) ions with ammonia.

Initially, the light blue hydroxide precipitates only to redissolve upon addition of more ammonia: Silver diammine fluoride ([Ag(NH3)2]F) is a topical medicament (drug) used to treat and prevent dental caries (cavities) and relieve dentinal hypersensitivity.