Question

Which kind of isomerism is exhibited by octahedral $Co(N{H}_3{)}_{4}B{r}_{2}Cl?$
[IIT-JEE, 2005]

• A. (a) geometrical
• B. (b) optical
• C. (c) ionisation
• D. (d) linkage

Answer 1

Answer: (A), (C)

The correct options are
A (a) geometrical
C (c) ionisation

It is given that$\left[Co\right(N{H}_3{)}_{4}B{r}_2]Cl$ is octahedral in shape.
It has bromine and chloride ions which could be inside or outside the coordination sphere right? so It shows ionisation isomerism like this:
$\left[Co\right(N{H}_3{)}_{4}B{r}_2]Cl\rightleftharpoons [Co(N{H}_3{)}_{4}B{r}_2{]}^{⨁}+C{l}^{\ominus }$
$\left[Co\right(N{H}_3{)}_{4}BrCl]Br\rightleftharpoons [Co(N{H}_3{)}_{4}BrCl{]}^{⨁}+B{r}^{\ominus }$
Also also, do not forget that geometric isomerism is also possible. How?
$\left[Co\right(N{H}_3{)}_{4}B{r}_2]Cl$ is of $M{a}_4{b}_2$ type, and it shows geometrical isomerism too. Remember, geometrical isomerism is the same as cis trans isomerism.