is a slightly pyramidalized molecule, with hybridization of the nitrogen somewhere between sp3
. The amine is flatter than an aliphatic amine, owing to conjugation of the lone pair
with the aryl
substituent. Thus, the experimental geometry reflects a balance between the stabilization of lone pairs in orbitals with higher s character and better stabilization via conjugation with the aryl ring for an orbital of pure p character. The pyramidalization angle between the CN bond and the bisector of the H-N-H angle is 142.5°.(For comparison, in more strongly pyramidal methylamine, this value is ~125°, while a planar nitrogen like that of formamide has an angle of 180°.) The CN distance is correspondingly shorter. In aniline, the CN and CC distances are close to 1.39 indicating the
-bonding between N and C. Consistent with these factors, substituted anilines with electron donating groups are more pyramidalized, while those with electron withdrawing groups are more planar.