A B3LYP/6-31G** study on the chlorination of ammonia by hypochlorous acid

B3LYP/6-31G** calculations were performed on the chlorination of NH3 by HOC l, considering explicit participation of zero, one, two, three and four wat er molecules. Detailed analysis of the free energy profiles shows the mecha nism is water-assisted. Cl transfer from the O of HOCl to the N of NH3 is a ccompanied by proton transfers along a chain of hydrogen-bonded water molec ules, Preferential stabilisation of the transition structure arises from co operative fluctuations involving the hydrogen-bonded chain of water molecul es. Calculations show solvent reorganization associated with proton translo cations is coupled with Cl transfer in the vicinity of the transition struc ture. (C) 2001 Elsevier Science B.V. All rights reserved.