Match List-I with List-II
| List-I Types of complexes | List-II Isomerisms |
| (A) [Co(NH3)4Cl2]+ | (I) Coordination |
| (B) [Co(en)3]3+ | (II) Linkage |
| (C) [Co(NH3)5(NO2)]Cl2 | (III) Geometrical |
| (D) [Cr(NH3)6][Co(CN)6] | (IV) Optical |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) - (III), (B) - (IV), (C) - (II), (D) - (I)
Isomers have the same formula but a different arrangement. In coordination compounds, stereoisomers differ in the spatial arrangement of ligands (geometrical, optical), and structural isomers differ in bonding (linkage, coordination, ionisation, solvate).
(A) \( \ce{[Co(NH3)4Cl2]^{+}} \) — This matches (III) Geometrical. In this octahedral [MA4B2] complex, the two Cl ligands can be next to each other (cis, 90°) or opposite each other (trans, 180°).
(B) \( \ce{[Co(en)3]^{3+}} \) — This matches (IV) Optical. Three bidentate en rings wrap around cobalt like a propeller; the complex and its mirror image are not superimposable, giving d and l forms.
(C) \( \ce{[Co(NH3)5(NO2)]Cl2} \) — This matches (II) Linkage. \( \ce{NO2^{-}} \) is an ambidentate ligand: it can bind through N (nitrito-N, yellow) or through O (nitrito-O, red).
(D) \( \ce{[Cr(NH3)6][Co(CN)6]} \) — This matches (I) Coordination. Both the cation and the anion are complexes, so the ligands can be interchanged between the two metals, giving \( \ce{[Co(NH3)6][Cr(CN)6]} \).
Shortcut: The pair (A)–(III) appears only in Option (4).