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

Ab initio molecular dynamics (MD) simulations for the reaction of formaldehyde radical anion and methyl chloride indicate that trajectories starting from a well-characterized single transition state reach either an electron-transfer (ET) product or a C-substituted S_N2 product. The two kinds of trajectories have different characteristics. Trajectories which lead to the S_N2 product state are simple, with C-C bond formation and C-Cl bond breaking essentially completed within 50 fs. By contrast, trajectories leading to the ET product are more complex with a sudden electron reorganization taking place around 15-30 fs; the major bonding changes and electron and spin reorganization are completed after 250 fs.