Indicate the type of isomerism exhibited by the following complex: $[Co(en)_3]Cl_3$
Show Hint
Complexes of the type $[M(aa)_3]$ and cis-$[M(aa)_2b_2]$ are usually chiral and show optical isomerism.
Trans forms of $[M(aa)_2b_2]$ are generally optically inactive due to symmetry.
Concept:
Isomerism in coordination compounds occurs when complexes have the same molecular formula but differ in spatial arrangement of ligands.
One important type is optical isomerism, where compounds exist as non-superimposable mirror images (enantiomers).
Step 1: Identify the nature of the complex.
The complex $[Co(en)_3]Cl_3$ contains the tris(ethylenediamine)cobalt(III) cation.
Here, 'en' (ethylenediamine) is a chelating bidentate ligand.
Step 2: Analyze geometry and symmetry.
The complex is of the type $[M(aa)_3]$, which forms an octahedral structure.
Due to the propeller-like arrangement of three bidentate ligands:
No plane of symmetry
No center of inversion
Hence, the molecule becomes chiral.
Step 3: Determine type of isomerism.
The complex exists as two non-superimposable mirror images:
Dextro (d) form
Laevo (l) form
These are optical isomers (enantiomers).
Step 4: Final conclusion.
The complex $[Co(en)_3]Cl_3$ exhibits optical isomerism.
