`CIF_(3)` exists but `FCl_(3)` does not - why ?

Explanation

Chorine has vacant 3d-orbital. Hence it can show +3 oxidation state by expansion of octet. In first excited state , three unparied electrons of Cl -atom participate in covalent bond formation with three F - atoms. As a result of this `CIF_(3)` is formed . On the other hand , fluorine cannot expand its octer due to the absence of d - orbital. Hence , `FCl_(3)` does not exist.