dichlorobisammine

Dichlorobisammine is a descriptor used in coordination chemistry for a metal complex in which two ammine ligands and two chloride ligands are bound to a central metal atom or ion. The generic formula is [M(NH3)2Cl2], with M representing the metal center. Ammine ligands are neutral molecules (NH3), while chloride ligands are anionic (Cl−).

Because two neutral ligands and two Cl− groups balance to the overall charge, the metal center is typically in the +2 oxidation state in neutral complexes of this type, though charged or coordinated species may occur in different formulations.

Geometrically, many M(NH3)2Cl2 complexes are square planar, especially for late transition metals such as Pt(II) and Pd(II). The relative arrangement of the two NH3 and two Cl− ligands can give cis and trans isomers.

A widely known example is cis-diamminedichloroplatinum(II) (cisplatin), an anticancer drug. The corresponding trans isomer is also known but has different properties. Palladium(II) and other metal centers also form dichlorobisammine complexes that are studied in inorganic synthesis and catalysis.

Note that dichlorobisammine is not a single compound; it is a ligand set that can describe any complex with two ammine and two chloride ligands across a metal center, with the full complex name specifying the metal, oxidation state, and geometry (for example, cis-diamminedichloroplatinum(II)).