Question

Which of the following compound CANNOT act as a Lewis base?

• A. $Cl{F}_3$
• B. $PC{l}_5$
• C. $N{F}_3$
• D. $S{F}_4$

Answer 1

The correct option is B

$PC{l}_5$

Answer: (b)

$PC{l}_5$ P has no lone pair of electrons hence it cannot acts as a base. But $N{F}_3$ (3 B.P + 1 L.P) , $Cl{F}_3$ (3 B.P + 2 L.P) and $S{F}_4$ (4 B.P +1 L.P) has lone pair of electrons so they will act as lewis base.
$PC{l}_5$ is a lewis acid because it has vacant orbitals to abstract electrons.