NH3
The NH3 molecule has C3v symmetry (Figure 4.18) and a
bonding scheme can be derived by considering the interaction
between the atomic orbitals of the N atom and the ligand
group orbitals of an appropriate H3 fragment. An appropriate
axis set has the z axis coincident with the C3 axis of NH3
(see worked example 3.2); the x and y axes are directed as
shown in Figure 4.19. Table 4.2 shows part of the C3v character
table. By seeing how each symmetry operation affects each
orbital of the N atom in NH3, the orbital symmetries are
assigned as follows: