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 molecu lar 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/6-3 11 + + G(d,p) level. It is shown that for the H3N-HBr complex only one wate r 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. (C ) 1999 Elsevier Science B.V. All rights reserved.