Systematic study of the nine hydrogen-bonded dimers involving ammonia, water, and hydrofluoric acid

The nine H-bonded dimers of NH3, OH2, and HF have been calculated by ab initio molecular orbital theory at the 6-31G* level with geometry optimization. Calculated dimerization energies (kilocalories/mole) are: H3N⋯HNH2, 2.9; H3N⋯HOH, 6.5; H3N⋯HF, 12.2; H2O⋯HNH2, 2.8; H2O⋯HOH, 5.6; H2O⋯HF, 9.2; HF⋯HNH2, 2.6; HF⋯HOH, 4.0; HF⋯HF, 5.9. Energies and geometries are compared with available experimental and ab initio values from the literature.