STRUCTURE OF COMPLEXES
Three linkage isomers are common for nitrite ligands, O-bonded, N-bonded, and bidentate O,O-bonded. The former two isomers have been characterized for the pentamminecobalt(III) system, i.e. [(NH3)5Co−NO2]2+ and [(NH3)5Co−ONO]2+, referred to as N-nitrito and O-nitrito, respectively. These two forms are sometimes called nitro and nitrito. An example of chelating nitrite is [Cu(bipy)2(O2N)]NO3 – "bipy" is the bidentate ligand 2,2′-bipyridyl. This bonding mode is sometimes described as κ2O,O-NO2.