Kinetics Studies of the Reactions of Main Fourth-Period Monocations (Ga+, Ge+, As+, and Se+) with Methyl Fluoride

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• 作者：Carmen Barrientos ; V铆ctor Manuel Ray贸n ; Antonio Largo ; Jos茅 脕ngel Sordo ; Pilar Redondo
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：August 22, 2013
• 年：2013
• 卷：117
• 期：33
• 页码：7742-7753
• 全文大小：559K
• 年卷期：v.117,no.33(August 22, 2013)
• ISSN：1520-5215

文摘

Thermodynamics and kinetics theoretical studies on the gas-phase reactions of fluoromethane with main fourth-period monocations (Ga⁺, Ge⁺, As⁺, and Se⁺) have been carried out. Density functional theory (in particular mPW1K functional) was employed in the description of the potential energy surfaces, and refinement of the energies were done at the CCSD(T) level. The reaction rate constants were estimated using variational/conventional microcanonical transition state theory. From a thermodynamic viewpoint, the fluorine abstraction product is predicted for Ga⁺ and Ge⁺, whereas for As⁺ and Se⁺ the elimination product, MCH₂⁺ (M = As, Se) + HF, is the preferred one. Nevertheless, the most favorable channel for the reactions of CH₃F with Ga⁺ and Se⁺ cations present a net activation barrier. In the case of Ga⁺, the reaction proceeds via an addition channel forming the adduct complex, CH₃FGa⁺, whereas for Se⁺ no reaction is found, in agreement with the experiments. The predicted reaction rate constants are in reasonable good agreement with the experimental values available. Apart from the harpoon-like mechanism, our results suggest that an oxidative addition mechanism seems to play a relevant role.