Amongst the following which one will have maximum 'lone pair - lone pair' electron repulsions?
- ClF3
- IF5
- SF4
- XeF2
Answer
(4) XeF2
Solution
Lone pairs on the central atom (VSEPR):
ClF3: sp3d, 3 bp + 2 lp (T-shape) ⇒ one lp–lp repulsion
IF5: sp3d2, 5 bp + 1 lp (square pyramidal) ⇒ no lp–lp repulsion
SF4: sp3d, 4 bp + 1 lp (see-saw) ⇒ no lp–lp repulsion
XeF2: sp3d, 2 bp + 3 lp (linear); all three lone pairs occupy the equatorial positions ⇒ three lp–lp repulsions at 120
∴ XeF2 has the maximum lone pair–lone pair repulsions.
Answer: (4)