JEE Main · 2018 · 08 Apr 2018 · Offline · Coordination Compounds

Consider the following reaction and statements :

[Co (NH_{3})_{4} Br_{2}]^{+} + Br^{-} \to [Co (NH_{3})_{3} Br_{3}] + NH_{3}

(I) Two isomers are produced if the reactant complex ion is a cis-isomer.
(II) Two isomers are produced if the reactant complex ion is a transisomer.
(III) Only one isomer is produced if the reactant complex ion is a transisomer.
(IV) Only one isomer is produced if the reactant complex ion is a cis-isomer.

The correct statements are :

(A)(II) and (IV)
(B)(I) and (II)
(C)(I) and (III)✓ Correct
(D)(III) and (IV)

Answer: (C)

Solution

Replacing one

NH X_{3}

[Co (NH X_{3}) X_{4} Br X_{2}] X^{+}

Br X^{-}

gives

[Co (NH X_{3}) X_{3} Br X_{3}]

, and the number of products depends on the starting geometry. From the cis reactant the two bromides are adjacent, so the incoming bromide can land either next to both, giving the facial arrangement, or next to only one, giving the meridional arrangement, so two isomers appear. From the trans reactant the two bromides are opposite and the four

NH X_{3}

sites are equivalent, so only the meridional product forms, a single isomer. The statements that hold are that the cis form gives two isomers and the trans form gives only one.

JEE Main · 2018 · 08 Apr 2018 · Offline · Single correct option

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JEE Main · 2018 · 08 Apr 2018 · Offline · Coordination Compounds

Solution

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