Which of the following has pπ - dπbonding

Which of the following has $p\pi - d\pi$ bonding
A $NO_3^-$
B $SO_3^{2-}$
C $BO_3^{3-}$
D $CO_3^{2-}$

Detailed Solution

A $p\pi - d\pi$ bond is formed by sideways overlap of a filled p orbital of one atom (here O) with an empty d orbital of the other atom.
N, B and C are second period elements with no d orbitals in their valence shell. In $NO_3^-$, $BO_3^{3-}$ and $CO_3^{2-}$, the $\pi$ bonding is of $p\pi - p\pi$ type.
S is a third period element with vacant 3d orbitals. In $SO_3^{2-}$, the S=O $\pi$ bond is formed by overlap of a 2p orbital of O with a 3d orbital of S ($p\pi - d\pi$ bonding).
So $SO_3^{2-}$ has $p\pi - d\pi$ bonding.

Pi Bonding with d Orbitals in past papers

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Practise Pi Bonding with d Orbitals All 2 questions This chapter in 2002 AIPMT