Linkage isomers are those that result when ambidentate ligand switches its coordinating atom. The first identified instance of linkage isomerism involved the nitrite ion, NO2-. The Lewis structure of this anion involves the resonance structures, including π-electron density spread out amog the three atoms of the anion. Therefore, The ligand can make a bond either via nitrogen atom (in this case the ligand is called nitro), or via oxygen (in this case the ligand is called nitrito). Another example can be the complexes with thiocyanate (SCN-) and/or isothiocyanate (NCS-). Hence, if the ligand makes a bond by using sulfur atom, the ligand will be thiocyanate or if it makes a bond by using nitrogen atom, then it will be called isothiocyanate ligand, and the chemical nature and nomenclature of complex will be different.