Trajectory studies of SN2 nucleophilic substitution. 4. Intramolecular and unimolecular dynamics of the Cl(super -)---CH(sub 3)Br and ClCH(sub 3)---Br(super -) complexes

Classical trajectory studies of the intramolecular and unimolecular dynamics of the Cl(-)---CH3Br complex reveal two different types in the dynamics of this complex. Excitation of low-frequency modes leads to Cl(-)+CH3Br, while excitation of intramolecular high-frequency CH3Br modes produce ClCH3---Br- complex. Central barrier region of the potential energy surface traps this complex and shows extensive barrier recrossing. A dynamical bottleneck for energy transfer exists between Cl(-)---CH3Br and ClCH3---Br- complexes.