Question

Which of the following has $p_{\pi}-d_{\pi}$ bonding

• A. $NO_{3}^{-}$
• B. $SO_{3}^{2-}$
• C. $BO_{3}^{3-}$
• D. $CO_{3}^{2-}$

Answer 1

Answer: (B)

$SO_{3}^{2-}$

Answer 2

$In \, SO_3^{2-} , \, the \, S \, is \, sp^3 hybridised, so$ In 'S' the three p-orbitals form $\sigma$-bonds with three oxygen atoms and unhybridised d-orbital is involved in $\pi$-bond formation $\, \, \, \, \, \, \, \, \, S_{10} = 1s^2,2s^22p_x^2 2p_y^12p_z^1$ In oxygen two unpaired p-orbitals are present, one is involved in $\sigma$-bond formation while other is used in $\pi$-bond formation. Thus, in $SO_3^{2-} p\pi \, and \, d\pi$ orbitals are involved for p$\pi -d\pi$ bonding.