Question

Explain hydrate (solvate) isomerism and linkage isomerism with suitable examples.

Answer 1

The hydrate (solvate) isomers and linkage isomers are both a type of structural isomers. Isomerism is a concept where more than one compound has the same chemical formula but a different arrangement of atoms or groups in it.

Complete step by step answer: 1) First of all let's understand the concept of isomers. The isomers are the compounds that have the same molecular or chemical formula but have a different arrangement of atoms or molecules.
2) Now let's see what the hydrate (solvate) isomers. The hydrate (solvate) isomers are the type of structural isomers where they have the same chemical formula but they differ in the arrangement of water molecules i.e. hydrate molecules. Let us see an example of hydrate isomer as below,
$[Cr{({H_2}O)_6}]C{l_3}$ and $[Cr{({H_2}O)_5}]C{l_2}.{H_2}O$
In the above structures, the attachment of the water molecule is different. In the first structure, there are all six water molecules attached to the central chromium metal and in the second structure, there are five water molecules that are attached to the central chromium metal i.e. inner sphere and one in the outer sphere.
3) Now let's talk about the linkage isomerism. The linkage isomerism is a type of structural isomerism in which the molecular formula of the compounds is the same but they differ in the connectivity to metals. Now let us see an example as below,
M-NCS and M-SCN
The above ligand is of thiocyanate which can bind to a metal through a nitrogen atom or sulfur atom which gives both structures as linkage isomers.

Note: The word hydrate stands for a water molecule. The hydrate isomerism is also called solvate isomerism as the solvent molecules attached to the metal atom decides the structure. The linkage isomerism is shown by ambidentate ligands in a coordination compound.