Question

The number of optical isomers exhibited by the iron complex (A) obtained from the following reaction is ______ $ FeCl_3 + KOH + H_2C_2O_4 \rightarrow A $

Hint:

For \( [M(AA)_3] \) type complexes, where AA is a symmetrical bidentate ligand, the complex is chiral and exists as two optical isomers (d and l forms).

Answer 1

Correct Answer: 2

The reaction provided involves FeCl₃, KOH, and H₂C₂O₄. The product formed, A, is likely a complex iron compound. Let's follow the steps to determine the number of optical isomers.

Step 1: Determine the Iron Complex

The reaction of FeCl₃ with oxalic acid (H₂C₂O₄) in the presence of KOH generally forms a complex known as potassium ferrioxalate, K₃[Fe(C₂O₄)₃].

Step 2: Identify the Coordination Sphere

The coordination number for iron (Fe) in K₃[Fe(C₂O₄)₃] is 6, as oxalate (C₂O₄) is a bidentate ligand, each donating two pairs of electrons.

Step 3: Understand Optical Isomerism

Optical isomerism occurs in complexes where the arrangement of ligands can exist as non-superimposable mirror images. For the complex K₃[Fe(C₂O₄)₃], this occurs because the oxalate ligands create a chiral center around the metal.

Step 4: Identify and Count the Optical Isomers

K₃[Fe(C₂O₄)₃] has two non-superimposable mirror images or enantiomers, known as the 'Δ' and 'Λ' forms, making a total of 2 optical isomers.

Conclusion

The number of optical isomers is 2. This solution falls perfectly within the given range of 2 to 2.

Answer 2

\( FeCl_3 + KOH + H_2C_2O_4 \rightarrow K_3[Fe(C_2O_4)_3] \)
\([Fe(C_2O_4)_3]^{3-} \text{ is } [M(AA)_3] \text{ type complex.} \) 
So total optical isomers = 2