Question

Which complex exhibits geometrical isomerism?

• A. \([\text{Co}(\text{NH}_{3})_{6}]^{3+}\)
• B. \([\text{PtCl}_{2}(\text{NH}_{3})_{2}]\)
• C. \([\text{CuCl}_{4}]^{2-}\)
• D. \([\text{Ni}(\text{CN})_{4}]^{2-}\)

Hint:

Square planar complexes of the type MA2B2 show cis and trans forms.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Geometrical isomerism needs different possible arrangements of ligands around the metal, as in square planar \(\text{MA}_{2}\text{B}_{2}\) or octahedral \(\text{MA}_{4}\text{B}_{2}\).

Step 2: Check the options
\([\text{Co}(\text{NH}_{3})_{6}]^{3+}\) has identical ligands and \([\text{CuCl}_{4}]^{2-}\) is tetrahedral.
\([\text{Ni}(\text{CN})_{4}]^{2-}\) is square planar with identical ligands.

Step 3: Match
\([\text{PtCl}_{2}(\text{NH}_{3})_{2}]\) is square planar of type \(\text{MA}_{2}\text{B}_{2}\), giving cis and trans forms. Option (B).

Final Answer:
\([\text{PtCl}_{2}(\text{NH}_{3})_{2}]\) shows geometrical isomerism. \[ \boxed{\text{(B) }[\text{PtCl}_{2}(\text{NH}_{3})_{2}]} \]