Consider the complex ions, trans \(-\left[\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]^{+}(\mathrm{A})\) and cis \(-\left[\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]^{+} \quad\) (B). The correct statement regarding them is:

(B) (A) cannot be optically active, but (B) can be optically active.

(A) both (A) and (B) cannot be optically active.

(C) both (A) and (B) can be optically active.

(D) (A) can be optically active, but (B) cannot be optically active.

JEE Main · 2020 · 05 Sep 2020 · Shift 2 · Coordination Compounds

Consider the complex ions, trans

- [Co (en)_{2} Cl_{2}]^{+} (A)

and cis

- [Co (en)_{2} Cl_{2}]^{+}

(B). The correct statement regarding them is:

(A)both (A) and (B) cannot be optically active.
(B)(A) cannot be optically active, but (B) can be optically active.✓ Correct
(C)both (A) and (B) can be optically active.
(D)(A) can be optically active, but (B) cannot be optically active.

Answer: (B)

Solution

In the trans isomer of

[Co (en) X_{2} Cl X_{2}] X^{+}

the two chlorides lie opposite each other, giving the molecule a plane of symmetry so that it coincides with its mirror image and is optically inactive. In the cis isomer the chlorides are adjacent, and the two chelating ethylenediamine rings leave no plane of symmetry, so it is chiral and optically active. Only the cis form can be optically active.

JEE Main · 2020 · 05 Sep 2020 · Shift 2 · Single correct option

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JEE Main · 2020 · 05 Sep 2020 · Shift 2 · Coordination Compounds

Solution

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