title: Kinetics studies of the reactions of main fourth-period monocations (Ga+, Ge+, As+, and Se+) with methyl fluoride.
abstract: 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.
authors.affiliation: Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Barrientos
authors.forename: Víctor Manuel
authors.initials: VM
authors.lastname: Rayón
authors.forename: Antonio
authors.initials: A
authors.lastname: Largo
authors.forename: José Ángel
authors.initials: JÁ
authors.lastname: Sordo
authors.forename: Pilar
authors.initials: P
authors.lastname: Redondo
mesh_terms: D001151:Arsenic / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D005708:Gallium / Q000737:chemistry*; D005857:Germanium / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D007700:Kinetics; D011789:Quantum Theory; D012643:Selenium / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D002412:Cations; D006845:Hydrocarbons, Fluorinated; D005857:Germanium; C029999:fluoromethane; D005708:Gallium; D012643:Selenium; D001151:Arsenic