title: Probing the reactivity of microhydrated α-nucleophile in the anionic gas-phase S(N)2 reaction.
abstract: To probe the kinetic performance of microsolvated α-nucleophile, the G2(+)M calculations were carried out for the gas-phase S(N)2 reactions of monohydrated and dihydrated α-oxy-nucleophiles XO(-)(H2O)(n = 1,2) (X = HO, CH3O, F, Cl, Br), and α-sulfur-nucleophile, HSS(-)(H2O)(n = 1,2), toward CH3Cl. We compared the reactivities of hydrated α-nucleophiles to those of hydrated normal nucleophiles. Our calculations show that the α-effect of monohydrated and dihydrated α-oxy-nucleophiles will become weaker than those of unhydrated ones if we apply a plot of activation barrier as a function of anion basicity. Whereas the enhanced reactivity of monohydrated and dihydrated ROO(-) (R = H, Me) could be observed if compared them with the specific normal nucleophiles, RO(-) (R = H, Me). This phenomena can not be seen in the comparisons of XO(-)(H2O)(n = 1,2) (X = F, Cl, Br) with ClC2H4O(-)(H2O)(n = 1,2), a normal nucleophile with similar gas basicity to XO(-)(H2O)(n = 1,2). These results have been carefully analyzed by natural bond orbital theory and activation strain model. Meanwhile, the relationships between activation barriers with reaction energies and the ionization energies of α-nucleophile are also discussed.
authors.affiliation: College of Chemistry and Key State Laboratory of Biotherapy, Sichuan University, Chengdu, 610064, China.
authors.forename: Wen-Yang
authors.initials: WY
authors.lastname: Zhao
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.forename: Si-Jia
authors.initials: SJ
authors.lastname: Ren
authors.forename: Xi-Guang
authors.initials: XG
authors.lastname: Wei
authors.forename: Fang-Zhou
authors.initials: FZ
authors.lastname: Qiu
authors.forename: Peng-Hui
authors.initials: PH
authors.lastname: Li
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Yi-Peng
authors.initials: YP
authors.lastname: Zhou
authors.forename: Chang-Zhen
authors.initials: CZ
authors.lastname: Yin
authors.forename: An-Pu
authors.initials: AP
authors.lastname: Chen
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhu
authors.forename: Yi
authors.initials: Y
authors.lastname: Ren
authors.forename: Kai-Chung
authors.initials: KC
authors.lastname: Lau
mesh_terms: D020650:Combinatorial Chemistry Techniques; D005740:Gases; D009574:Nitro Compounds / Q000737:chemistry; D013455:Sulfur; D013816:Thermodynamics; D014867:Water
chemical_list: D005740:Gases; D009574:Nitro Compounds; D014867:Water; D013455:Sulfur
keywords: activation strain model; alpha-effect; gas basicity; gas-phase SN2 reaction; microhydrated nucleophile