Structure, Hybridization & Geometry of Amines

Structure & Angle:

$$\text{Hybridization} = sp^3, \quad \text{Geometry} = \text{Pyramidal}, \quad \text{Bond Angle} \approx 108^\circ \text{ (due to lp--bp repulsion)}$$

Concept: Nitrogen in amines is $$sp^3$$ hybridized with three bond pairs and one lone pair, resulting in a pyramidal geometry.

Amine Inversion (Pyramidal Inversion / Walden Inversion):

Chiral tertiary amines with three different alkyl groups cannot be resolved into optically active enantiomers at room temperature due to rapid "umbrella-like" nitrogen inversion via a planar $$sp^2$$ transition state.