Question

Match List-I with List-II. 

List-I	Complex
A	[Pt(NH₃)₂Cl₂]
B	[Co(en)₃]Cl₃
C	[Co(NH₃)₅NO₂]Cl₂
D	[Cr(H₂O)₆]Cl₃

 

List-II	Type of isomerism
I	Optical
II	Solvate
III	Geometrical
IV	Linkage

• A. A-III, B-I, C-IV, D-II
• B. A-II, B-I, C-III, D-IV
• C. A-IV, B-III, C-II, D-I
• D. A-I, B-II, C-IV, D-III

Hint:

Square planar complexes show geometrical isomerism, \(en\)-complexes may show optical isomerism, and \(\ce{NO2^-}\) ligand shows linkage isomerism.

Answer 1

The Correct Option is A

Step 1: Understanding the Topic:
This question focuses on "Coordination Compounds" and the various types of isomerism that exist within these complexes. Coordination isomers have the same chemical formula but different spatial or structural arrangements. These differences can arise from the way ligands are attached (linkage), the arrangement of ligands in space (geometrical/optical), or the distribution of solvent molecules (solvate). Understanding these is key to identifying different versions of the same chemical complex.
Step 2: Key Formulas and Approach:
We identify the specific type of isomerism by looking for structural markers:
Geometrical: Cis/Trans arrangements in $MA_2B_2$ or $MA_4B_2$.
Optical: Chiral complexes (often with bidentate ligands) that have mirror images.
Linkage: Presence of ambidentate ligands (like $NO_2^-$ or $SCN^-$).
Solvate: Water molecules moving between the coordination sphere and the crystal lattice.

Step 3: Detailed Explanation:

A. \([Pt(NH_3)_2Cl_2]\): This square planar complex exists in two forms: cis (ligands on the same side) and trans (ligands on opposite sides). This is the hallmark of geometrical isomerism. A matches with III.
B. \([Co(en)_3]^{3+\):} This octahedral complex contains three bidentate ethylenediamine ligands. Because it is chiral and possesses no plane of symmetry, it exists as a pair of non-superimposable mirror images. This is optical isomerism. B matches with I.
C. \([Co(NH_3)_5NO_2]Cl_2\): The $NO_2^-$ ligand is ambidentate, meaning it can link to the metal via Nitrogen (nitro) or Oxygen (nitrito). This is linkage isomerism. C matches with IV.
D. \([Cr(H_2O)_6]Cl_3\): In this series, water molecules can swap positions with chloride ions inside or outside the bracket (e.g., $[Cr(H_2O)_5Cl]Cl_2 \cdot H_2O$). This is solvate isomerism. D matches with II.
Step 4: Final Answer:
The correct matching sequence is A-III, B-I, C-IV, D-II, corresponding to option (D).