Question

Change in composition of co-ordination sphere yields which types of isomers [DCE 2002]
(A) Optical
(B) Geometrical
(C) Ionisation
(D) None of these

Answer 1

Hint: Stereoisomers interconnected by non-superimposable mirror images of one another are known as optical isomers. Geometric isomers are two or more coordination compounds that have the same quantity, kind, and type of atoms as well as bonds but differ in the atoms' spatial configurations. The interchange of ions inside and outside the coordination sphere is a characteristic of ionisation isomerism.

Complete answer:The interchange of ions inside and outside the coordination sphere is a component of ionisation isomerism. Ionization isomerism is the term used to describe how these isomers produce various ions in solution. Let us take an example of $[Cr{{({{H}_{2}}O)}_{6}}]C{{l}_{3}}$ and$[Cr{{({{H}_{2}}O)}_{3}}C{{l}_{3}}].3{{H}_{2}}O$. The complex $[Cr{{({{H}_{2}}O)}_{6}}]C{{l}_{3}}$gives three $C{{l}^{-}}$ions, whereas $[Cr{{({{H}_{2}}O)}_{3}}C{{l}_{3}}].3{{H}_{2}}O$ gives three ${{H}_{2}}O$ molecules. So, these two complexes differ in only the ions produced in the solution.
Thus, Change in composition of the coordination sphere yields ionisation isomers.

Correct Option: C) Ionisation

Additional Information: When several compounds with the same chemical formula but different chemical structures exist, this phenomenon is known as isomerism. Stereo and structural isomers are the two categories of isomers.

Note: J. J. Berzelius discovered isomerism for the first time in 1827. Louis Pasteur performed early research on stereoisomers by crystallizing racemic acid to divide it into its two optically active tartaric acid components (1848). Isomerism is significant in the fields of clinical pharmacology and pharmacotherapeutics. A new era in drug development has started because of drug isomerism.