Invariant description of the behavior of electrons in donor–acceptor molecules

The sharing of electrons in the donor–acceptor complexes BH3NH3, BCl3NH3, AlH3NH3, AlCl3NH3, and GaCl3NH3 is investigated by the one-electron delocalization indices. Three prevailing aspects of the analysis are: (1) the nature of the compounds based upon the average number of electrons in atomic basins, (2) the quantitative extent of electron delocalization based upon the basin–basin indices, and (3) the sharing of electrons between the groups constituting the molecules. Because the analysis is rooted in the first-order density matrix, no reference to orbitals has been invoked. This study provides new insight into the electronic basis of the DA interactions.