Fig. 7. The molecular orbital interaction between PH3 and H2 in (PH3)2H2.
a Qualitative molecular orbital diagram for pyramidal AH3 (where A = N, P, Sb, Bi) obtained from the symmmetry adapted linear combination of atomic orbitals of H3 (C3v) and A fragments (adapted from Figures 4–9 in ref. 75). The orbitals of each fragment are aligned vertically, in order of increasing energy from bottom to top, under the corresponding column of panel a, with H3 on the left side, AH3 in the middle and A on the right side. The 2a1 highest occupied molecular orbital (HOMO), where the electron lone pair is located, is highlighted by a red circle. b Molecular orbital diagram for H2, showing the completely filled σ bonding molecular orbital and the empty σ* anti-bonding lowest unoccupied molecular orbital (LUMO) highlighted by a red circle. c Isolobal orbital overlap interaction between the 2a1 molecular orbital of AH3 and the σ* anti-bonding molecular orbital of H2.