Obtaining accurate energetics for gas-phase bimolecular nucleophilic substitution (SN2) reactions.
EMSL Project ID
32191
Abstract
There is considerable interest in understanding the atomic-level dynamics of gas-phase bimolecular nucleophilic substitution (SN2) reactions of the typeX- + CH3Y â?? XCH3 + Y-
These reactions are of central importance in gas-phase ion chemistry and organic reaction mechanisms. Studies of these reactions in the gas-phase have provided the opportunity to probe the intrinsic reaction mechanism without solvent, and it is well known that the reactions proceed via a double-well potentia. The two wells correspond to loose ion-dipole complexes, i.e., the pre- and post-reaction complexes X----CH3Y and XCH3---Y-, which are separated by a [X--CH3--Y]- central barrier. This potential model has been confirmed by numerous theoretical and experimental studies, including a structural characterization of a SN2 ion-dipole complex.
We propose to obtain the most accurate energetics for the above reaction with X and Y = F, Cl, Br, and I. Obtaining accurate energetics requires the use of large basis sets to enable extrapolation to the full basis set limit. We are unable to run the calculations with the larger basis sets on clusters available at our university. The chemistry focused and unique large computing resources at EMSL combined with NWChem will enable us to quickly obtain the results for the calculations, which are the final piece for our peer reviewed article that we intend to submit once we have obtained the high accuracy data.
Project Details
Project type
Limited Scope
Start Date
2008-10-09
End Date
2008-11-10
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Mikosch J, J Zhang, S Trippel, C Eichhorn, R Otto, R Sun, WA De Jong, M Weidemuller, WL Hase, and R Wester. 2013. "Indirect dynamics in a highly exoergic substitution reaction." Journal of the American Chemical Society 135(2):4250-4259.
Sun R, K Park, WA De Jong, H Lischka, TL Windus, and WL Hase. 2012. "Direct dynamics simulation of dioxetane formation and decomposition via the singlet ·O–O–CH2–CH2 · biradical: Non-RRKM dynamics." Journal of Chemical Physics 137(4):044305-1 to 044305-11. doi:10.1063/1.4736843
Zhang J, U Lourderaj, SV Addepalli, WA De Jong, and WL Hase. 2008. "Quantum Chemical Calculations of the Cl- + CH3I ? CH3Cl + I- Potential Energy Surface." Journal of Physical Chemistry A 113(10):1976-1984. doi:10.1021/jp808146c