Question

Chiral complex from the following is 

 

• A. trans – [Co(NH₃)₄Cl₂] ⁺
• B. cis – [PtCl₂(en)₂] ²⁺
• C. cis – [PtCl₂(NH₃)₂]
• D. trans – [PtCl₂(en)₂] ²⁺

Hint:

For identifying chiral complexes:
• Check for the absence of planes of symmetry or center of symmetry.
• Cis configurations with bidentate ligands (like en) often result in chiral complexes.
• Trans configurations are usually symmetric and achiral.

Answer 1

The Correct Option is B

To determine which of the given complexes is chiral, we need to understand the concept of chirality in coordination chemistry. A chiral compound is one which is not superimposable on its mirror image, often lacking an internal plane of symmetry.

1. Cis and trans isomers differ in their spatial arrangement. In general, trans isomers are not chiral because they tend to have a plane of symmetry.
2. Consider the complexes:
   • trans – [Co(NH₃)₄Cl₂]⁺: Trans coordination typically has a plane of symmetry, making this complex achiral.
   • cis – [PtCl₂(NH₃)₂]: Cis configuration may lack symmetry; however, this specific complex is not chiral due to the equal environment of the amine groups.
   • cis – [PtCl₂(en)₂] ²⁺: This complex features two ethylenediamine (en) ligands in a cis arrangement. These bidentate ligands create a situation where there is no plane of symmetry, making the complex chiral.
   • trans – [PtCl₂(en)₂] ²⁺: As previously mentioned, the trans arrangement generally results in an internal plane of symmetry, rendering this complex achiral.

Based on this reasoning, the chiral compound among the options is cis – [PtCl₂(en)₂] ²⁺. The cis arrangement of the bidentate ethylenediamine ligands creates a complex with no internal plane of symmetry, confirming its chirality.