Question

Which of the following compounds exhibits linkage isomerism
A . [Co(en)3]Cl3
B . [Co(NH3)6[Cr(CN)6]
C . [Co(en)2NO2Cl]Br
D . [Co(NH3)5Cl]Br2

Answer 1

Hint: In this question we have used the concept of linkage isomerism in coordinate compounds. A phenomenon known as isomorphism occurs when distinct compounds with the same chemical formula have different chemical characteristics and atom configurations. Isomers are substances with the same chemical formula but distinct structural configurations.

Complete answer:The linkage isomers are those isomers in which at least one of the ligands of the coordinating molecule is different from the donor atom. In other words, there is a difference in the connection between the donor atoms.
Only when a chemical contains a ligand that may bind to the metal atom in two (or more) distinct ways can this form of isomerism exist.
Linkage isomers have the same molecular formula but differ in the linkage of the ligand atom to the central metal atom.

[Co(en)2NO2Cl]Br can exhibit linkage isomerism since NO2 is the ambidentate ligand in this coordination complex. This ligand is the reason the coordination complex shows linkage isomerism.
When the central metal atom is bonded with nitrogen, the ligand is NO2. When the metal atom is bonded with oxygen, the ligand is ONO.

The correct answer is C.

Note: Ambidentate ligand is present in coordination complexes that exhibit linkage isomerism. One donor atom at a time can only attach to the main metal atom when an ambidentate ligand has two donor atoms. Dentate refers to the ligand's denticity, while the word "Ambi" indicates both. The coordination complex's denticity refers to the number of donor atoms that the ligand uses to bind to the main metal atom.
Depending on how many of the ligand's donor atoms attach to the central metal atom, ligands can be monodentate, bidentate, or multidentate.