Q71 / 180 · NEET 2026 (Re-NEET) · Chemistry
The complex which has facial and meridional isomers is
(Given : py = pyridine and en = H$_2$N$-$CH$_2-$CH$_2-$NH$_2$)
(Given : py = pyridine and en = H$_2$N$-$CH$_2-$CH$_2-$NH$_2$)
- A$[\text{Ni(en)}_2(\text{H}_2\text{O})_2]^{2+}$
- Correct answerB$[\text{Cr(py)}_3(\text{Cl})_3]$
- C$[\text{Cr(H}_2\text{O})_6]^{3+}$
- D$[\text{Co(NH}_3)_4(\text{H}_2\text{O})_2]^{3+}$
Solution
Facial and meridional isomerism is exhibited by octahedral complexes of the type $[MA_3B_3]$.
$[\text{Ni(en)}_2(\text{H}_2\text{O})_2]^{2+}$ is of the type $[M(AA)_2B_2]$, which shows cis and trans isomerism.
$[\text{Cr(py)}_3(\text{Cl})_3]$ is of the type $[MA_3B_3]$, which shows facial (fac) and meridional (mer) isomerism.
$[\text{Cr(H}_2\text{O})_6]^{3+}$ is of the type $[MA_6]$, which does not show geometrical isomerism.
$[\text{Co(NH}_3)_4(\text{H}_2\text{O})_2]^{3+}$ is of the type $[MA_4B_2]$, which shows cis and trans isomerism.
Answer: $[\text{Cr(py)}_3(\text{Cl})_3]$
$[\text{Ni(en)}_2(\text{H}_2\text{O})_2]^{2+}$ is of the type $[M(AA)_2B_2]$, which shows cis and trans isomerism.
$[\text{Cr(py)}_3(\text{Cl})_3]$ is of the type $[MA_3B_3]$, which shows facial (fac) and meridional (mer) isomerism.
$[\text{Cr(H}_2\text{O})_6]^{3+}$ is of the type $[MA_6]$, which does not show geometrical isomerism.
$[\text{Co(NH}_3)_4(\text{H}_2\text{O})_2]^{3+}$ is of the type $[MA_4B_2]$, which shows cis and trans isomerism.
Answer: $[\text{Cr(py)}_3(\text{Cl})_3]$
Hence, the correct answer is option: 'B'.