Explain, why the P - O bond length in POCl 3 is 1 . 45 A ∘ . Whereas, the sum of the single bond covalent radii of phosphorus and oxygen is 1 . 83 A ∘ .

In POCl 3 structure, oxygen and chlorine are in resonance. Initially phosphorous makes double bond with oxygen and chlorine forms single bond with phosphorous but, after resonance in between oxygen and chlorine, oxygen gets double bond character and chlorine gets single bond character. We know that, bond length of single bond is more than bond length of double bond because bond strength of double bond is more than single bond. Because of this character, change in bond's bond length of P - O bond increases while, bond length between P - Cl bond decreases and hence, according to practical data, bond length of P - O should have been 1 . 83 A ∘ but, it is 1 . 45 A ∘ .

Explain, why the P - O bond length in POCl 3 is 1 . 45 A ∘ . Whereas, the sum of the single bond covalent radii of phosphorus and oxygen is 1 . 83 A ∘ .

In POCl 3 structure, oxygen and chlorine are in resonance. Initially phosphorous makes double bond with oxygen and chlorine forms single bond with phosphorous but, after resonance in between oxygen and chlorine, oxygen gets double bond character and chlorine gets single bond character. We know that, bond length of single bond is more than bond length of double bond because bond strength of double bond is more than single bond. Because of this character, change in bond's bond length of P - O bond increases while, bond length between P - Cl bond decreases and hence, according to practical data, bond length of P - O should have been 1 . 83 A ∘ but, it is 1 . 45 A ∘ .