Question

Which one of the following has the largest number of isomers? (R $=$ alkyl group, en $=$ ethylenediamine)
$A.{[Ru{(N{H_3})_4}Cl]^ + } \\\ B.{[Co{(N{H_3})_5}Cl]^{2 + }} \\\ C.{[Ir{(P{R_3})_2}H(CO)]^{2 + }} \\\ D.{[Co{(en)_2}C{l_2}]^ + } \\\$

Answer 1

Hint : ${[Co{(en)_2}C{l_2}]^ + }$ has largest number of isomers which include both geometrical as well as optical (cis and Trans). It includes stereoisomers which have d isomers, I isomers, and optically inactive form of isomers. Bidentate ligand that has two teeth or atoms which coordinate with the center of the atom directly. It can form two bonds to a metal ion.

Complete Step By Step Answer:
Isomers are compounds that contain the same number of atoms and same amphoral formula but are different by the arrangement of the atoms.
In the given question,
en is the bidentate ligand.
${[Co{(en)_2}C{l_2}]^ + }$ Shows optical and geometrical isomerism.
The optical isomers include cis and Trans isomers.
The geometrical isomers that are the stereoisomers included form isomers and l form isomers.
Here en is the ligand that has two teeth or atoms which coordinate with the center of the atom directly.
It can form two bonds to a metal ion.
${[Co{(en)_2}C{l_2}]^ + }$ Has largest number of isomers which include both geometrical as well as optical (cis and Trans). It includes stereoisomers which have d isomers, I isomers, and optically inactive form of isomers.
So D is the correct option.

Note :
To find the number of participating isomers in a compound that is possible, the formula is $X = {2^n}$ for stereoisomers.
Where n is the number of stereoisomers atoms. Here both optical and stereoisomers are present. Hence maximum number of isomers. Cis, Trans, d form and l form all are present in ${[Co{(en)_2}C{l_2}]^ + }$ .