Question

Determine the hybridization of the circled atoms and the number of p electrons that the circled atoms in the compound shown contribute to the aromatic system of delocalized pi electrons.

Answer 1

3.a.

N1 \(\&\) N3 - \(sp^{2}\) hybridized. The lone pair in the \(sp^{2}\) orbital projecting outward from the ring in perpendicular to the p orbitals. As a result, the lone pair does not contribute to the aromatic system.

N2 - \(sp^{2}\) hybridized. The lone pair in the p orbital is part of the \(\pi\) electron cloud. As a result, the lone pair (two p electrons) contributes to the aromatic system.

3.b.

N1 - \(sp^{2}\) hybridized. The lone pair in the \(sp^{2}\) orbital projecting outward from the ring in perpendicular to the p orbitals. As a result, the lone pair does not contribute to the aromatic system.

3.c.

O1 - \(sp^{2}\) hybridized. One of its lone pairs in the p orbital is part of the \(\pi\) electron cloud. As a result, the lone pair (two p electrons) contributes to the aromatic system.

N2 - \(sp^{2}\) hybridized. The lone pair in the \(sp^{2}\) orbital projecting outward from the ring in perpendicular to the p orbitals. As a result, the lone pair does not contribute to the aromatic system.

Refer the below image for labelling the \(\mathrm{N} \& \mathrm{O}\) atoms.