One transition state leading to two product states: ab initio molecular dynamics simulations of the reaction of formaldehyde radical anion and methylchloride

Ab initio molecular dynamics (MD) simulations for the reaction of formaldeh yde radical anion and methyl chloride indicate that trajectories starting f rom a well-characterized single transition state reach either an electron-t ransfer (ET) product or a C-substituted S(N)2 product, The two kinds of tra jectories have different characteristics. Trajectories which lead to the S( N)2 product state are simple, with C-C bond formation and C-Cl bond breakin g essentially completed within 50 fs, By contrast, trajectories leading to the ET product are more complex with a sudden electron reorganization takin g place around 15-30 fs; the major bonding changes and electron and spin re organization are completed after 250 fs. (C) 1999 Elsevier Science B.V. All rights reserved.