Fig. 4.17 A qualitative MO diagram for the formation of BH3 using the ligand group orbital approach. The three H atoms in the
H3 fragment are out of bonding range with each other, their positions being analogous to those in the BH3 molecule. Orbitals
LGO(2) and LGO(3) form a degenerate pair (e’ symmetry), although for clarity, the lines marking their orbital energies are drawn
apart; similarly for the three 2p atomic orbitals of boron. [Exercise: where do the nodal planes lie in LGO(2) and LGO(3)?]