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:
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)