Difference between revisions of "Ammine complex"
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Latest revision as of 19:18, 21 September 2010
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In coordination chemistry, ammine complexes are metal complexes containing at least one ammonia (NH3) ligand. "Ammine" is spelled this way due to historical reasons; in contrast, alkyl or aryl bearing ligands are spelled with a single "m".
Examples
Cobalt(III)
Cobalt(III) salts frequently actually contain hexaamminecobalt(III) (e.g. hexaamminecobalt(III) chloride, [Co(NH3)6]Cl3). Tetraamminedichlorochromium(III) chloride, [Cr(NH3)4Cl2]Cl, has two forms - the cis isomer is violet, while the trans isomer is green.
Copper(II)
The tetraamminecopper(II) [Cu(NH3)4]2+, is a much deeper blue than the bare copper ion. The formation of this deep blue solution is indicative of the presence of copper in qualitative inorganic analysis. Addition of dilute ammonia to an aqueous solution containing copper(II) ions causes the light blue hydroxide to precipitate. Addition of excess ammonia causes the blue hydroxide to dissolve, giving the deep blue solution of tetraamminecopper(II):
- Cu2+ + 2 OH− → Cu(OH)2 (s)
- Cu(OH)2 + 4 NH3 + 2 H2O → [Cu(NH3)4(H2O)2]2+ (aq) + 2OH−
Silver(I)
Formation of the diamminesilver ion, [Ag(NH3)2]+, allows the generally insoluble silver chloride to dissolve in aqueous ammonia. It is used as a soluble form of silver(I) in Tollen's reagent.
Cisplatin
Cisplatin is a coordination compound containing two chlorido and two ammine ligands. It is a metal-based drug used in chemotherapy.
