Hückel transformation theory of the hybridization problem in NH3

Hückel transformation theory is applied to the study of the hybridization problem in ground state NH3. Under assumptions similar to those recently introduced for H2O, minimization of the model Hückel energy at the valence level yields a trigonometric relation between bond angle and hybridization parameter showing that hybridization opens the interbond angle beyond 90°. A further orthogonal transformation mixing in AOs belonging to A1 and E symmetry yields four orthogonal sp3 hybrids of C3v symmetry on nitrogen that can be engaged in the axially symmetric lone pair and three equivalent straight N–H bonds making the experimental interbond angle.