Total number of isomers of `[Co(en)_(2)CI_(2)]^(+)` is

Options

A. 3
B. 4
C. 2
D. 5

Answer

A

Explanation

Ethylenediamine (or any bidentate ligand) always spans adjacent corner of an octahedron, but tge `C1^(-)` ligands can be on either adjacent or opposite corners. Therefore there are two diastereoisomers, cis trans :

Because the trans isomer has several symmetry plane-one cuts through the Co and the en ligands -it is achrial and has no enantiomers. However, the cis isomer is chiral and exists as a pair of enantiomers that are non identical mirror images. We can see that the cis enantiomer on the right is not the same as the one the left if we rotate it by `180^(@)` about the vertical N-Co-N Axis.