Theoretical studies on complexes with ammonia: comparison with H2O complexes: hydrogen bonding

High-level theoretical results for structures, dissociation energies and vibrational frequencies of the ammonia complexes NH3-N-2, NH3-CO, NH3-O-2, NH3-NO, NH3-H-2, NH3-F-2, NH3-HF, NH3-Ne, NH3-Ar, NH3-CO2, NH3-N2O and NH3-NH3 are reported, and compared with results for corresponding complexes of H2O. While complexes of H2O with N-2, CO, NO, Ne, Ar and NH3 are hydrogen bonded, of the complexes with NH3 only NH3-NH3 qualifies. However, for NH3-CO, NH3-N-2 and NH3-Ne structures with weak hydrogen bonding are predicted by present theoretical results. Structures of H-2, F-2, HF, CO2 and N2O complexes with NH3 are similar to those with H2O, not hydrogen bonded, having AB face N of NH3. Their dissociation energies D-e are close to those of H2O-AB. Due to complex formation, some large changes are noted in vibrational frequencies and infrared intensities, especially for the NH3 dimer and for NH3-HF.