Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Near-Thermal Reactions of Au + ( 1 S, 3 D) and AuX + with CH 3 X (X = Br, I): A Combined Experimental and Computational Analysis
Ist Teil von
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 2021-03, Vol.125 (8), p.1696-1710
Ort / Verlag
United States
Erscheinungsjahr
2021
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Reactions of Au
(
S,
D) and AuX
with CH
X (X = I and Br) were performed in the gas phase by utilizing a selected-ion drift cell reactor. These experiments were done at room temperature as well as reduced temperature (∼200 K) at a total pressure of 3.5 Torr in helium. Rate coefficients, product sequencing, and branching fractions were obtained for all reactions to evaluate reaction efficiencies and higher-order processes. Reactions of both Au
states proceed with moderate efficiencies as compared to the average dipole orientation model with these neutral substrates. Results from this work revealed that, dependent on the reacting partner, Au
(
S) exhibits, among others, halogen abstraction, HX elimination, and association. By comparison, Au
(
D) participates primarily in charge transfer and halogen abstraction. Dependent on the halogen ligand, AuX
ions induce several processes, including association, charge transfer, halogen loss, and halogen substitution. AuI
reacting with CH
Br resulted in association exclusively, whereas the AuI
/CH
I and AuBr
/CH
Br systems exhibited halogen loss as the dominant process. By contrast, all possible bimolecular pathways occurred in the reaction of AuBr
with CH
I. Observed products indicate that displacement of bromine by iodine on gold is favored in ionic products, consistent with the thermochemical preference for formation of the Au
-I bond. All AuX
reactions proceed at maximum efficiency. Potential energy surfaces calculated at the B3LYP/def2-TZVPP level of theory for the AuX
reactions are in good agreement with the available thermochemistry for these species and with previously calculated structures and energetics. Experimental and computational results are consistent with a mechanism for the AuX
/CH
Y systems where bimolecular products occur either via direct loss of the halogen originally on Au or via a common intermediate resulting from methyl migration in which the Au center is three-coordinate.