Answer to Question #84649 in Inorganic Chemistry for Sk Abidur Rahaman

Question

Arrange and explain the bond angles in OF2 and OCl2.

Answer 1

Accordng to VSEPR theory the centarl atom (O) has 2 BP and 2LP, electron geometry - tetrahedral, molecular shape (AX₂E₂) is bent, ideal bond angle should be 109.5 .

The experimental data shows that the bond angle in the molecules of OF₂ and OCl₂ differ from ideal bond angle:

The experimental data shows that the bond angle in the molecules of OF₂ and OCl₂ differ from ideal bond angle:

Consider electronagativity:

χ(O) = 3.50

χ(F) = 4.10

χ(Cl) = 2.83

Chlorine is less electronegative than oxygen. Therefore, the chlorine ligands do not effectively localize the central oxygen electrons into four tetrahedrally oriented domains, and ligand-ligand repulsions are more responsible for the bond angle. Bond angke in OCl₂ becomes more than the ideal one.

Fluorine ligands are more electronegative than the central atom of oxygen, they draw bonding electron density away from the central atom. The space occupied by the bonding domains is lessend, and the ligands can approach each other more closely. Lone pair domains occupy a greater space and thereby push the ligand domains together. For the same centaral atom (O), the greater the ligand electronegativity the smaller the bond angle will be. Thus, OF₂ has smaller bond angle than OCl₂ (103.3 < 110.9)