Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Isomerism in coordination compounds describes molecules with the same chemical formula but different structural arrangements or spatial orientations. It is broadly classified into Structural Isomerism and Stereoisomerism.
Structural Isomerism includes: 1. Linkage Isomerism (arises with ambidentate ligands like or ); 2. Ionization Isomerism (interchange of ions between the coordination sphere and the ionization sphere); 3. Coordination Isomerism (interchange of ligands between cationic and anionic entities); 4. Solvate Isomerism (differing number of molecules inside the coordination sphere).
Stereoisomerism includes: 1. Geometrical Isomerism ( and ); 2. Optical Isomerism (chiral molecules that are non-superimposable mirror images).
Geometrical Isomerism: In square planar complexes of type , (adjacent) and (opposite) forms exist. In octahedral complexes of type , isomers are designated as (facial) and (meridional).
Optical Isomerism: Common in octahedral complexes containing chelating didentate ligands such as ethylenediamine (). Enantiomers are labeled as (dextro) and (laevo) based on their rotation of plane-polarized light.
📐Formulae
💡Examples
Problem 1:
Identify the type of isomerism exhibited by the pair and .
Solution:
Ionization Isomerism.
Explanation:
These isomers yield different ions in solution. gives ions, whereas gives ions.
Problem 2:
How many geometrical isomers are possible for the square planar complex ?
Solution:
geometrical isomers.
Explanation:
For a square planar complex of type , three isomers are possible by fixing one ligand and rotating the other three.
Problem 3:
Explain why shows optical isomerism while does not.
Solution:
is chiral, whereas has a plane of symmetry.
Explanation:
Optical isomerism requires the absence of a plane of symmetry. In , the didentate ligands create a helical, non-superimposable structure. The -isomer of is achiral due to its symmetrical arrangement.