[1] The complex cis-dichlorotetrakis(dimethylsulfoxide)ruthenium(II) (RuCl2(dmso)4) exhibits linkage isomerism of dimethyl sulfoxide ligands due to S- vs. O-bonding.
Trans-dichlorotetrakis(dimethylsulfoxide)ruthenium(II) does not exhibit linkage isomers.
Linkage isomerism was first noted for nitropentaamminecobalt(III) chloride, [Co(NH3)5(NO2)]2+.
This cationic cobalt complex can be isolated as either of two linkage isomers.
In the red linkage isomer, the nitrito is bound through one oxygen atom.