Ion Molecule Reaction Dynamics

  1. Bimolecular reactions of an anion X- with a methyl halide CH3Y, e.g. the SN2 reaction X- + CH3Y CH3X + Y-, are important ion-molecule reactions, particularly in organic chemistry. The kinetics of X- + CH3Y ion-molecule reactions are extensively studied in this project both experimentally and computationally. Experiments can accurately measure the reaction rate constant and branching ratios with varied temperature. Direct dynamics simulations were performed to predict and/or reproduce the experiments results, and unveil the mechanisms of different reaction pathways at atomic level. RRKM models can be used to comprehend the proposed mechanism, where intermediate dissociation is involved. The project aims to find the temperature dependence of X- + CH3Y ion-molecule reaction kinetics and understand the atomistic mechanisms.
  2. Our research focuses on two topics:
  3. (1) Cl-(D2O)1-3 with CH3Br[1]
    (2) OH- with CH3I[2]
  4. fig1
    Frames of a sample CH3OH---I- postreaction complex formation trajectory leading to the CH3OH + I- SN2 products via an indirect mechanism.

    References

    1. 1. "Temperature Dependence of the Rate Constants and Branching Ratios for the Reactions of Cl-(D2O)1-3 with CH3Br and Thermal Dissociation Rates for Cl-(CH3Br)." Journal of American Chemical Society 119, 577-584 (1997)
      J. V. Seeley, R. A. Morris, A. A. Viggiano, H. Wang and W. L. Hase
    2. 2. "Temperature Dependence of the OH- + CH3I Reaction Kinetics. Experimental and Simulation Studies and Atomic-Level Dynamics." Journal of Physical Chemistry A 117, 14019-14027 (2013)
      J. Xie, S. C. Kohale, W. L. Hase, S. G. Ard, J. J. Melko, N. S. Shuman and A. A. Viggiano