Proton transfer of NH3--HCl catalyzed by only one molecule

The proton transfer in NH3--HCl by only one molecule of catalyst was studied by using the MP2 method with the large 6-311++G(2d,2p) basis set. The results showed that the proton transfer occurred from HCl to NH3 when catalyst molecule A not only as a proton donor strongly donated the proton to the Cl atom, but as an acceptor strongly accepted the proton from the NH3 molecule in the cyclic H-bond structure.