Isomerism in Coordination Compounds

Isomers are two or more compounds that share the same chemical formula but differ in how their atoms are arranged in space. Because the arrangement of atoms differs, isomers differ in one or more physical or chemical properties even though their molecular formula is identical.

Coordination compounds show two principal kinds of isomerism, and each of these is further subdivided.

Stereoisomerism

Stereoisomers have the same chemical formula and the same chemical bonds — the ligands are attached to the central metal through the same donor atoms — but they differ in the spatial arrangement of those ligands around the metal. Stereoisomerism is further divided into:

• Geometrical isomerism
• Optical isomerism

Structural Isomerism

Structural isomers, by contrast, have different bonds — the ligands (or their donor atoms, or their distribution between metal centres) are actually connected differently, not merely arranged differently in space. Structural isomerism is further divided into:

• Linkage isomerism
• Coordination isomerism
• Ionisation isomerism
• Solvate isomerism …