The influence of water molecules on the proton position in H3N–HX (X=F, Cl, Br) complexes

Quantum chemical calculations have been performed to investigate the molecular structures and proton positions of the first few water clusters of H3N–HX (X=F, Cl, Br) hydrogen-bonded complexes. The minimum energy structures were found using the density functional methods at the modified B3-LYP/6-311++G(d, p) level. It is shown that for the H3N–HBr complex only one water molecule is necessary for a proton transfer to occur. In the case of H3N–HCl and H3N–HF systems, the presence in the cluster of two and three water molecules, respectively, induces proton transfer to the ammonia subunit.