Coordination Isomers

Coordination isomers arise in coordination compounds where BOTH the cation and the anion are themselves complex ions; interchanging one or more ligands between the cationic and anionic coordination entities produces a different isomer with the same overall formula. For example, in [Co(NH₃)₆][Cr(CN)₆] the ammonia ligands are bound to cobalt and the cyanide ligands to chromium, while in its coordination isomer [Cr(NH₃)₆][Co(CN)₆] the assignment is reversed -- ammonia now on chromium, cyanide now on cobalt. Further examples given are [Cr(NH₃)₅CN][Co(NH₃)(CN) …