Question

Which of the following compounds show optical isomerism ?

1. cis - [Co(NH3)4Cl2]+ 2. trans - [Co(en)2Cl2]+

3. cis - [Co(en)2Cl2]+ 4. [Co(en)3]3+

Select the correct answer using the codes given below:

• A. 1 and 2
• B. 2 and 3
• C. 3 and 4
• D. 1, 3 and 4

Answer 1

Answer: (C)

3 and 4

Answer 2

(1) cis - [Co(NH3)4 Cl2]+ has plane of symmetry as well as centre of symmetry ; so optically inactive.

(2) trans - [Co(en)2Cl2]+ has plane of symmetry as well as centre of symmetry ; so optically inactive.

(3) cis - [Co(en)2Cl2]+ lacks plane of symmetry as well as centre of symmetry ; so optically active.

(4) [Co(en)3]3+ lacks axis of internal rotation ; so optically active.