Question

The total number of possible isomers for the complex compound $[Cu^{II}(NH_3)_4] [Pt^{II}Cl_4] $ are

• A. 5
• B. 6
• C. 3
• D. 4

Answer 1

The Correct Option is D

The given complex compound is $[Cu^{II}(NH_3)_4][Pt^{II}Cl_4]$. This is an example of a coordination compound consisting of two complex ions: a tetraamminecopper(II) cation $[Cu(NH_3)_4]^{2+}$ and a tetrachloroplatinate(II) anion $[PtCl_4]^{2-}$.

In order to determine the number of possible isomers, we need to consider the types of isomerism that may occur in this complex:

1. Geometrical Isomerism: This isomerism occurs in planar complexes, such as $[PtCl_4]^{2-}$. However, in a square planar complex like $[PtCl_4]^{2-}$ with identical ligands, no geometrical isomers are possible.
2. Linkage Isomerism: This type of isomerism arises when a ligand can attach through different atoms. This is not applicable here because ammonia and chloride ions bond through a single atom.
3. Ionization Isomerism: This type of isomerism arises when the compound can produce different ions in solution. This complex does not exhibit ionization isomerism because its ions are fixed.
4. Cis-Trans Isomerism: Cis-trans isomerism is not possible here because the square planar geometry of $[PtCl_4]^{2-}$ and tetrahedral geometry in $[Cu(NH_3)_4]^{2+}$ do not allow for different spatial arrangements significant enough to exhibit this kind of isomerism.

For $[Cu^{II}(NH_3)_4][Pt^{II}Cl_4]$, the primary type of isomerism possible is:

• Coordination Isomerism: This occurs because there are two complex ions, and exchanging the ligands between these can result in different structural entities.

For these types of compounds, there can be different ways of alternating which of the ions receives amine ligands and which receives chloride ions, and the number of possible isomers can be calculated considering different arrangements:

1. Original complex: $[Cu(NH_3)_4]^{2+}$ and $[PtCl_4]^{2-}$.
2. Isomers can be formed by exchanging some of the ligands between the metal centers since both centers are capable of accepting different types of ligands.

Upon analysis, there are 4 different structures or possible isomers for this type of mixed complex due to coordination isomerism.

Thus, the correct number of possible isomers for the complex compound $[Cu^{II}(NH_3)_4][Pt^{II}Cl_4]$ is 4.