The complex \( [Co(NH_3)_4(NO_2)_2]Cl \) will show.........
(A) Linkage isomerism
(B) Ionization isomerism
(C) Coordination isomerism
(D) Geometrical isomerism
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
Each kind of structural isomerism or stereoisomerism needs a particular feature in the complex. In \( \ce{[Co(NH3)4(NO2)2]Cl} \), cobalt is +3 (x + 4(0) + 2(−1) + (−1) = 0), with four \( \ce{NH3} \) and two \( \ce{NO2-} \) ligands in an octahedral complex cation, and \( \ce{Cl-} \) as the counter ion.
(A) Linkage isomerism — Correct. \( \ce{NO2-} \) is an ambidentate ligand: it can bind through nitrogen (nitrito-N) or through oxygen (nitrito-O), so isomers with \( \ce{Co-NO2} \) and Co–ONO bonds exist.
(B) Ionization isomerism — Correct. The counter ion \( \ce{Cl-} \) can exchange places with a coordinated \( \ce{NO2-} \): \( \ce{[Co(NH3)4(NO2)2]Cl} \) and \( \ce{[Co(NH3)4(NO2)Cl]NO2} \) give different ions in solution.
(C) Coordination isomerism — Incorrect. This needs both cation and anion to be complex ions, which exchange ligands, as in \( \ce{[Co(NH3)6][Cr(CN)6]} \); here the anion is a simple \( \ce{Cl-} \).
(D) Geometrical isomerism — Correct. An octahedral complex of the type \( \ce{[MA4B2]} \) has cis and trans isomers: the two \( \ce{NO2-} \) groups can be next to each other or opposite each other.