Direct ab initio molecular dynamics study on a microsolvated SN2 reaction of OH−(H2O) with CH3Cl

Abstract

Reaction dynamics for a microsolvated S N 2 reaction OH − ͑H 2 O͒ +CH 3 Cl have been investigated by means of the direct ab initio molecular dynamics method. The relative center-of-mass collision energies were chosen as 10, 15, and 25 kcal/ mol. Three reaction channels were found as products. These are ͑1͒ a channel leading to complete dissociation ͑the products are CH 3 OH+Cl − +H 2 O: denoted by channel I͒, ͑2͒ a solvation channel ͑the products are Cl − ͑H 2 O͒ +CH 3 OH: channel II͒, and ͑3͒ a complex formation channel ͑the products are CH 3 OH¯H 2 O+Cl − : channel III͒. The branching ratios for the three channels were drastically changed as a function of center-of-mass collision energy. The ratio of complete dissociation channel ͑channel I͒ increased with increasing collision energy, whereas that of channel III decreased. The solvation channel ͑channel II͒ was minor at all collision energies. The selectivity of the reaction channels and the mechanism are discussed on the basis of the theoretical results.

Ion‐Pair SN2 Reaction of OH− and CH3Cl: Activation Strain Analyses of Counterion and Solvent Effects

“…[14] Other authors have used correlated levels of ab initio theory, such as the second-order Møller-Plesset theory,f or the exploration of the PES in the gas phase thus observing aT Sw ith C s symmetry and as mall central barrier of approximately 2.8 kcal mol À1 . [15] Moreover,t rajectory analyses based on ab initio molecular dynamics calculations have been performed to reveal the importance of water transfer from the incoming nucleophile to the leaving group in the microsolvated model reactions of OH À + CH 3 Cl [16] and OH À + CH 3 I [17] systems.…”

Exit Channel Dynamics in a Micro-Hydrated SN2 Reaction of the Hydroxyl Anion

“…Trajectory calculations on the OH − (H 2 O) + CH 3 Cl reaction 9 suggest that in this system the water molecule can be transferred over the nucleophile during the reaction and immediately attached to the leaving Cl − . This course of the reaction would be in accordance with the textbook S N 2 mechanism in which the substitution is a fast and direct process as has been experimentally observed using crossed beam ion imaging.…”

“…Refs. [2][3][4][5][6][7][8][9][10][11] This is because the underlying reaction dynamics could add to our understanding of how to apply our extensive knowledge of gas phase reactions to systems in the liquid phase. A recurrent finding for almost all of these reactions is that the formation of solvated reaction products is strongly suppressed with respect to their unsolvated counterparts.…”

Computer aided-molecular design of high performance nano-carbon materials: Na+ on graphenes

“…Diffusion processes of the Na + ion on the carbon clusters were investigated by means of direct molecular orbitalmolecular dynamics (MO-MD) method [14][15][16]. The total energy and energy gradient on the multi-dimensional potential energy surface of the Na + -graphenes were calculated at each time step at the AM1-MO level of theory, and then classical equation of motion is full-dimensionally solved.…”