Question

What are hydrate isomers? Explain with an example.

Answer 1

The exchange of free solvent molecules such as water, ammonia, alcohol, etc., in the crystal lattice with a ligand in the coordination entity, will give different isomers. These types of isomers are called solvate isomers. If the solvent molecule is water, then these isomers are called hydrate isomers.

For example, the complex with the chemical formula \[\ce{CrCl3.+6H2O}\] has three hydrate isomers as shown below.

\[\ce{[Cr(H2O)6]Cl3}\]	a violet colour compound and gives three chloride ions in solution
\[\ce{[Cr(H2O)5Cl]Cl2.H2O}\]	a pale green colour compound and gives two chloride ions in solution
\[\ce{[Cr(H2O)4Cl2]Cl.2H2O}\]	dark green colour compound and gives one chloride ion in solution