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.

Ion Mobility-Mass Spectrometry: Time-Dispersive Instrumentation

“… 154 − 156 The electronic state separations are notable in that ion mobility separations are facilitated strictly by long-range ion-neutral interactions at low temperature, which were accessed through liquid-nitrogen cooling of the drift cell to temperatures as low as 77 K. This electronic state selectivity of transition metals by low temperature ion mobility has been subsequently studied by several laboratories 157 , 158 and has been utilized in the study of state-specific ion-neutral reaction chemistry in the ion mobility experiment. 159 , 160 Russell and co-workers extended low-temperature ion mobility studies to differentiating the electronic state configurations of atomic and organic ions. 161 Several noteworthy ion mobility experiments have also been conducted under liquid helium temperature.…”

Selectivity of C–H Activation and Competition between C–H and C–F Bond Activation at Fluorocarbons

“…Overall, all calculations cited in the following paragraph used appropriate methods.As shown above, the C-H bond can be activated in the reaction of non-lanthanide ions with CH 3 F. Several experimental and computational studies have been carried out to search for the factors that control the selectivity. Reactions of Au + ( 1 S) and Au + ( 3 D) with CH 3 F were carried out in a drift cell in He at room and low temperatures in order to show the influence of the electronic state of the ion on the outcome of the reaction 24,132. Ground state Au…”

Aurocarbons: Binary Gold Carbides, Binary Carbon Aurides and their Derivatives

“…reactions 2 and 3. Alternate processes are observed in the related reaction of Au + with CH 3 Br 17, 18 and CH 3 l 17,19 . As reviewers, we ask what would be formed were Au + so reacted with CH 2 F 2 (cf.…”