Question

The complex that can show fac- and mer-isomers is:

• A. $\left[CO{\left(N{O}_2\right)}_3{\left(N{H}_3\right)}_3\right]$
• B. $\left[PtC{l}_2{\left(N{H}_3\right)}_2\right]$
• C. $\left[CO{\left(N{H}_3\right)}_{4}C{l}_2\right]$
• D. $\left[COC{l}_2{\left(en\right)}_2\right]$

Answer 1

The correct option is A

$\left[CO{\left(N{O}_2\right)}_3{\left(N{H}_3\right)}_3\right]$

The explanation for the correct option:

(A) -

$\left[\mathrm{Co}{\left(N{O}_2\right)}_3{\left(N{H}_3\right)}_3\right]$

• Meridional is referred to as Mer -isomer while facial is fac isomer.
• The identical ligands are on a shared face of a polyhedral complex in a fac-isomer, whereas in the Mer- isomer, they are on a plane that bisects the polyhedron.
• Note that $\left[M{A}_3{B}_3\right]$type complex shows fac and Mer isomerism.
• Therefore, $\left[\mathrm{Co}{\left(N{O}_2\right)}_3{\left(N{H}_3\right)}_3\right]$is the type of$\left[M{A}_3{B}_3\right]$.

The explanation for the incorrect options:

(B) -

$\left[PtC{l}_2{\left(N{H}_3\right)}_2\right]$

The given complex $\left[PtC{l}_2{\left(N{H}_3\right)}_2\right]$ only shows geometrical isomerism i.e., cis-isomer and trans-isomer.

(C) -

$\left[\mathrm{Co}{\left(N{H}_3\right)}_{4}C{l}_2\right]$

The given complex, $\left[\mathrm{Co}{\left(N{H}_3\right)}_{4}C{l}_2\right]$ only show geometrical isomerism i.e cis-isomer and trans-isomer.

(D) -

$\left[\mathrm{Co}C{l}_2{\left(en\right)}_2\right]$

The given complex $\left[\mathrm{Co}C{l}_2{\left(en\right)}_2\right]$ also shows geometrical isomerism i.e cis-isomer and trans-isomer.

Hence, option (A) is the correct answer.