ANALYSIS OF ELECTRON-DONOR ACCEPTOR COMPLEXES - H3N.F2, H3N.CL2, AND H3N.CLF

An extended geminal model has been applied to study the electron donor-acceptor complexes H3N.F2, H3N-Cl2, and H3N.ClF. By adopting a [9s, 6p, 2d/7s, 4p, 2d/4s, 2p] contracted Gaussian-type basis set, the equilibrium N-X (X = nearest halogen atom) distances are predicted to be 2.76 angstrom (H3N.F2), 2.57 angstrom (H3N.Cl2), and 2.30 angstrom (H3N.ClF). The predicted binding energies are 6.8 kJ/mol (H3N-F2), 24.6 kJ/mol (H3N.Cl2), and 45.1 kJ/mol (H3N.ClF). An energy decomposition analysis demonstrates the similarity between these three complexes. The Coulombic interaction between the distorted monomers is found to be the main origin of the intermolecular interaction. A decomposition of the Coulombic term into electrostatic and inductive terms shows that the latter is approximately 4 times larger than the former for all the three complexes.