title: Near-thermal reactions of Au(+)(1S,3D) with CH3X (X = F,Cl).
abstract: Reactions of Au(+)((1)S) and Au(+)((3)D) with CH(3)F and CH(3)Cl have been carried out in a drift cell in He at a pressure of 3.5 Torr at both room temperature and reduced temperatures in order to explore the influence of the electronic state of the metal on reaction outcomes. State-specific product channels and overall two-body rate constants were identified using electronic state chromatography. These results indicate that Au(+)((1)S) reacts to yield an association product in addition to AuCH(2)(+) in parallel steps with both neutrals. Product distributions for association vs HX elimination were determined to be 79% association/21% HX elimination for X = F and 50% association/50% HX elimination when X = Cl. Reaction of Au(+)((3)D) with CH(3)F also results in HF elimination, which in this case is thought to produce (3)AuCH(2)(+). With CH(3)Cl, Au(+)((3)D) reacts to form AuCH(3)(+) and CH(3)Cl(+) in parallel steps. An additional product channel initiated by Au(+)((3)D) is also observed with both methyl halides, which yields CH(2)X(+) as a higher-order product. Kinetic measurements indicate that the reaction efficiency for both Au(+) states is significantly greater with CH(3)Cl than with CH(3)F. The observed two-body rate constant for depletion of Au(+)((1)S) by CH(3)F represents less than 5% of the limiting rate constant predicted by the average dipole orientation model (ADO) at room temperature and 226 K, whereas CH(3)Cl reacts with Au(+)((1)S) at the ADO limit at both room temperature and 218 K. Rate constants for depletion of Au(+)((3)D) by CH(3)F and CH(3)Cl were measured at 226 and 218 K respectively, and indicate that Au(+)((3)D) is consumed at approximately 2% of the ADO limit by CH(3)F and 69% of the ADO limit by CH(3)Cl. Product formation and overall efficiency for all four reactions are consistent with previous experimental results and available theoretical models.
authors.affiliation: Department of Chemistry, University of Central Arkansas, Conway, Arkansas 72035, United States. billt@uca.edu
authors.forename: William S
authors.initials: WS
authors.lastname: Taylor
authors.forename: Cullen C
authors.initials: CC
authors.lastname: Matthews
authors.forename: Ashley J
authors.initials: AJ
authors.lastname: Hicks
authors.forename: Kendall G
authors.initials: KG
authors.lastname: Fancher
authors.forename: Li Chen
authors.initials: LC
authors.lastname: Chen
mesh_terms: D006046:Gold / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D008737:Methyl Chloride / Q000737:chemistry*; D013696:Temperature
chemical_list: D006845:Hydrocarbons, Fluorinated; C029999:fluoromethane; D006046:Gold; D008737:Methyl Chloride