JEE Advanced 2024 — Paper 1 — CHEM-I solution

JEE Advanced2024Paper 1CHEM-I

Among the following options, select the option in which each complex in Set-I shows geometrical isomerism and the two complexes in Set-II are ionization isomers of each other.

[en = H $_{2}$ NCH $_{2}$ CH $_{2}$ NH $_{2}$ ]

A
Set-I: [Ni(CO) $_{4}$ ] and [PdCl $_{2}$ (PPh $_{3}$ ) $_{2}$ ]
Set-II: [Co(NH $_{3}$ ) $_{5}$ Cl]SO $_{4}$ and [Co(NH $_{3}$ ) $_{5}$ (SO $_{4}$ )]Cl
B
Set-I: [Co(en)(NH $_{3}$ ) $_{2}$ Cl $_{2}$ ] and [PdCl $_{2}$ (PPh $_{3}$ ) $_{2}$ ]
Set-II: [Co(NH $_{3}$ ) $_{6}$ ][Cr(CN) $_{6}$ ] and [Cr(NH $_{3}$ ) $_{6}$ ][Co(CN) $_{6}$ ]
C
Set-I: [Co(NH $_{3}$ ) $_{3}$ (NO $_{2}$ ) $_{3}$ ] and [Co(en) $_{2}$ Cl $_{2}$ ]
Set-II: [Co(NH $_{3}$ ) $_{5}$ Cl]SO $_{4}$ and [Co(NH $_{3}$ ) $_{5}$ (SO $_{4}$ )]Cl
D
Set-I: [Cr(NH $_{3}$ ) $_{5}$ Cl]Cl $_{2}$ and [Co(en)(NH $_{3}$ ) $_{2}$ Cl $_{2}$ ]
Set-II: [Cr(H $_{2}$ O) $_{6}$ ]Cl $_{3}$ and [Cr(H $_{2}$ O) $_{5}$ Cl]Cl $_{2} \cdot$ H $_{2}$ O

Solution

Set-I check (geometrical isomerism in each complex):

For option (C): [Co(NH $_{3}$ ) $_{3}$ (NO $_{2}$ ) $_{3}$ ] is an octahedral $M a_{3} b_{3}$ type complex and exhibits facial/meridional (fac/mer) isomerism. [Co(en) $_{2}$ Cl $_{2}$ ] is an octahedral $M (AA)_{2} b_{2}$ type and exhibits cis/trans isomerism. Both show geometrical isomerism. $✓$

Option (A) fails because [Ni(CO) $_{4}$ ] is tetrahedral with four identical ligands and shows no geometrical isomerism.

Option (B): [Co(en)(NH $_{3}$ ) $_{2}$ Cl $_{2}$ ] does show GI, but the Set-II pair are coordination isomers (cation and anion exchanging metals), not ionization isomers.

Option (D): [Cr(NH $_{3}$ ) $_{5}$ Cl]Cl $_{2}$ has only one stereoisomer (no GI), and the Set-II pair are hydrate (solvate) isomers, not ionisation.

Set-II check (ionisation isomers):

For option (C): [Co(NH $_{3}$ ) $_{5}$ Cl]SO $_{4}$ ionises to release SO $_{4}^{2 -}$ as the counter-ion, while [Co(NH $_{3}$ ) $_{5}$ (SO $_{4}$ )]Cl releases Cl $^{-}$ . They swap the ligand inside the sphere with the counter-ion outside, which is the defining feature of ionisation isomerism. $✓$

$∴$ Option (C) is correct.

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