Question

Out of the following which will show geometrical isomerism as facial and meridional isomers?

• A. $\left[Pt\right(N{H}_3{)}_{2}C{l}_2]$
• B. $\left[Co\right(en{)}_{2}C{l}_2]Cl$
• C. $\left[Co\right(N{H}_3{)}_{3}C{l}_3]$
• D. $\left[Cr\right(N{H}_3{)}_{4}C{l}_2]Cl$

Answer 1

The correct option is C $\left[Co\right(N{H}_3{)}_{3}C{l}_3]$

Compounds having the formula $\left[M{A}_3{B}_3\right]$ exhibits fac and mer isomerism.
The fac isomer is also known as the facial isomer or the cis isomer. Three $A$ ligands are present on one triangular face and the three $B$ ligands are present on opposite triangular faces.
The mer isomer is also known as the meridional isomer or the trans isomer.