List various types of isomerism possible for coordination compounds, giving an example of each
Solution and Explanation
(a) Geometric isomerism:
This type of isomerism is common in heteroleptic complexes. It arises due to the different possible geometric arrangements of the ligands. For example: 
(b) Optical isomerism:
This type of isomerism arises in chiral molecules. Isomers are mirror images of each other and are Non superimposable. 
(c) Linkage isomerism:
This type of isomerism is found in complexes that contain ambidentate ligands. For example: \([Co(NH_3)_5 (NO_2)]Cl_2\) and \([Co(NH_3)_5 (ONO)Cl_2\) Yellow form Red form
(d) Coordination isomerism:
This type of isomerism arises when the ligands are interchanged between cationic and anionic entities of differnet metal ions present in the complex. \([Co(NH_3)_6] [Cr(CN)_6]\) and \([Cr(NH_3)_6] [Co(CN)_6] \)
(e) Ionization isomerism:
This type of isomerism arises when a counter ion replaces a ligand within the coordination sphere. Thus, complexes that have the same composition, but furnish different ions when dissolved in water are called ionization isomers.
For e.g.,\( Co(NH_3)_5SO_4)Br\) and \(Co(NH_3)_5Br]SO_4. \)
(f) Solvate isomerism:
Solvate isomers differ by whether or not the solvent molecule is directly bonded to the metal ion or merely present as a free solvent molecule in the crystal lattice. \([Cr[H_2O)_6]Cl_3 [Cr(H_2O)_5Cl]Cl_2┹”¦H_2O [Cr(H_2O)_5Cl_2]Cl┹”¦2H_2O \) Violet Blue-green Dark green
Top Questions on Coordination Compounds
The Crystal Field Theory (CFT) of coordination compounds is based on the effect of different crystal fields (provided by the ligands taken as point charges) on the degeneracy of d-orbital energies of the central metal atom/ion. The splitting of the d-orbitals provides different electronic arrangements in strong and weak crystal fields. In tetrahedral coordination entity formation, the d-orbital splitting is smaller as compared to the octahedral entity.
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The Crystal Field Theory (CFT) of coordination compounds is based on the effect of different crystal fields (provided by the ligands taken as point charges) on the degeneracy of d-orbital energies of the central metal atom/ion. The splitting of the d-orbitals provides different electronic arrangements in strong and weak crystal fields. In tetrahedral coordination entity formation, the d-orbital splitting is smaller as compared to the octahedral entity.
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Concepts Used:
Isomerism in Coordination Compounds
Isomers in Coordination Compounds
Stereoisomers occur when the ligands have the same bonds, but the bonds are in different orientations relative to one another. Structural isomerism occurs when the bonds are different. Isomers are distinct compounds that can have different physical properties such as color, crystal structure, and melting point.
Cis and Trans Stereoisomers
In octahedral complexes—with four of one ligand and two of another—and square planar complexes—with two of one ligand and two of another—there are two different arrangements of the same atoms with the same bonds. These different arrangements are called cis and trans. In cis molecules, the two ligands are on the same side of the complex. In trans molecules, the similar ligands are on the opposite sides of the molecules, meaning the bond angle is 180 degrees.
Optical Stereoisomers
Optical isomerism occurs when a molecule is not superimposable with its mirror image.
Fac and Mer Stereoisomers
When three identical ligands occupy one face of an octahedron, the isomer is said to be facial or fac. If these three ligands and the metal ion are in one plane, the isomer is said to be meridional or mer.