Direct ab initio molecular dynamics study on a S(N)2 reaction OH-+(CHCl)-Cl-3 -> CH3OH+Cl--> Cl-: Effect of non-zero impact parameter on the reaction dynamics

摘要

Direct ab initio molecular dynamics (MD) calculations have been applied to a S(N)2 reaction OH- + CH3Cl -> CH3OH + Cl-. The collision dynamics with non-zero impact parameters were treated in the present study, and the results are compared with the near collinear collision dynamics previously reported by us [H. Tachikawa, M. Igarashi, T. Ishibashi, J. Phys. Chem. A 106 (2002) 10977]. The collision energy was fixed to 25 kcal/mol. The product state distribution obtained for the non-zero impact parameter collision dynamics was slightly different from that of the collinear collision. The distribution of relative translational energy between products Cl- and CH3OH in the non-zero impact parameter collision dynamics was shifted to higher energy region from that of collinear collision. Also, it was found that the mean translational energy of the product has a maximum at non-zero impact parameter (b = 0.6-1.2 angstrom). The reaction mechanism is discussed on the basis of theoretical results. (c) 2005 Elsevier B.V. All rights reserved.