Question

The number of isomers possible for \[[Pt(en){(N{O_2})_2}]\] is:
A. 2
B. 3
C. 4
D. 1

Answer 1

Hint: Compounds that bear the same molecular formulae, but different structural formulae are called isomers. This phenomenon is known as isomerism. Isomers not only show different structural formulas but also differ primarily in their physical properties and in some cases, their chemical properties as well. Isomerism is broadly classified into two main categories, A. Structural isomerism and B. Stereoisomerism.

Complete Step by Step Solution:
As mentioned in the figure below, only 3 linkage isomers are possible in \[[Pt(en){(N{O_2})_2}]\].
They are: \[[Pt(en){(N{O_2})_2}]\] ; \[[Pt(en){(ONO)_2}]\] ; \[[Pt(en)(N{O_2})(ONO)]\]

Linkage isomerism is found in two or more coordination compounds in which the donor atom of at least one of the ligands is different (i.e., the connectivity between atoms is different).

This type of isomerism can occur only when the compound contains a ligand that can bind to the metal atom in two (or more) different ways. We can take –CN as an example. CN can attach/connect/interact with the metal ion with both its atoms i.e C and N. It is important to note that not all coordination compounds have linkage isomers. Linkage isomers have differences in both their physical and chemical properties.

Additional information: Structural isomerism can be further divided into the following subtypes-
1. Chain isomerism
2. Functional isomerism
3. positional isomerism
4. Metamerism isomerism
5. Tautomerism isomerism
6. Ring-chain isomerism

Note: There are mainly two types of isomers, these are constitutional isomers and stereoisomers. Compounds with various atom connections or bonds are known as constitutional isomers. Stereoisomers are compounds that have the same chemical formula and the structural formula but they differ in the orientation of space.