Question

Which of the following compound has non zero dipole moment?

• A. $PC{l}_3$
• B. $PC{l}_2{F}_3$
• C. $PC{l}_3{F}_2$
• D. $PCl{F}_4$

Answer 1

The correct option is A $PC{l}_3$

In $PC{l}_3$ dipole moment is non zero as lone pair being more electronegative tends to attract $e^{-}$ density towards its ey. Hence has dipole moment.

In $PC{l}_2{F}_3\to$ The two $F$ at axial positions cancel out each others dipole effect and $2Cl$ and $1F$ at equitorial.

$\because Cl$ has less electronegativity than $F$. So resultant dipole of $Cl\sim F$.

$\therefore$ cancelling each others dipole effects resulting in zero dipole moment.

In $PC{l}_3{F}_2$, The two $F$ at axial positions cancel each others dipole effect and at equitorial the $3Cl$ bonds cancels out each others dipole effect resulting in zero dipole moment.

In $PCl{F}_4$, The two $F$ at axial positions cancel out each others effect and at equitorial the the resultant electron attracting tendency of $2F>1Cl$ thereby having a non-zero dipole.

So, according to me, $PC{l}_3$ and $PC{l}_4$ have non-zero dipole.