Question

What is shape of interhalogen compound so that central halogen exhibits +3 oxidation state?

• A. Tetrahedral
• B. Bent 'T' shape
• C. Square pyramidal
• D. Square planar

Hint:

$XX'_3$ (e.g., $ClF_3$) is always T-shaped due to 2 lone pairs on the central atom.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Interhalogen compounds of the type \( XY_{3} \) have the central halogen \( X \) in a +3 oxidation state.
Step 2: Key Formula or Approach:
Use VSEPR theory to determine the geometry:
1. Total valence electrons of central halogen (Group 17) = 7.
2. Number of electrons used for 3 single bonds with \( Y \) = 3.
3. Remaining electrons = 4, which equals 2 lone pairs.
4. Steric number = 3 bond pairs + 2 lone pairs = 5.
Step 3: Detailed Explanation:
For a steric number of 5, the electron domain geometry is trigonal bipyramidal (\( sp^3d \)).
According to VSEPR theory, the two lone pairs will occupy equatorial positions to minimize repulsion.
The resulting molecular geometry (shape) formed by the three bond pairs is T-shaped.
Due to lone pair-bond pair repulsions, the bond angles are slightly less than 90$^{\circ}$, making it a "Bent T-shape".
Step 4: Final Answer:
The shape of the interhalogen compound where the central atom is in the +3 oxidation state is Bent 'T' shape.