RESUMEN
State-specific reactions of Cu(+)((1)S,(3)D) were carried out in a selected ion drift cell apparatus with SF6 and SF5Cl. Copper ions were prepared in a glow discharge utilizing Ne as the working gas. Analysis of Cu(+) states using ion mobility mass spectrometry (IMS) indicated the presence of both Cu(+)(3d(10)) and Cu(+)(3d(9)4s(1)) configurations attributable to the (1)S ground and (3)D first excited states of this metal ion, respectively. State-specific product formation in reactions of these ions with the two neutral substrates of interest here was determined using IMS along with both known and calculated energetic requirements for product formation. These experiments indicate that Cu(+)((1)S) associates with both SF6 and SF5Cl; however, the process is approximately four times as efficient with the latter neutral under these conditions. Association is also observed as a minor product between Cu(+)((3)D) and both neutral reactants. Inefficient formation of SF3(+) occurs as the sole bimolecular product from SF6 via Cu(+)((3)D). In contrast, Cu(+)((3)D) reacts with SF5Cl in rapid parallel bimolecular processes yielding SF3(+) and CuCl(+). These results also indicate that CuCl(+) initiates additional higher-order processes which result in SF5(+) and SF4Cl(+). The energetics associated with the formation of SF3(+) suggest that a copper halide neutral byproduct must also be formed, requiring a more complex mechanism than simple dissociative charge-transfer.
RESUMEN
State-specific reactions of the potent greenhouse gas SF5CF3 with Cu(+) were carried out in a selected ion drift cell apparatus. Copper ions were prepared in a glow discharge utilizing Ne as the working gas. Analysis of these ions using ion mobility mass spectrometry (IMS) indicated the presence of both Cu(+)(3d(10)) and Cu(+)(3d(9)4s(1)) configurations. Subsequent analysis indicates that the 3d(10) configuration consists of Cu(+)((1)S) exclusively whereas the 3d(9)4s(1)configuration is composed primarily of Cu(+)((3)D) with small contributions from Cu(+)((1)D). State-specific product formation in reactions of these ions with SF5CF3 was determined using IMS along with the known energetic requirements for product formation. These experiments reveal that Cu(+) excited states initiate fragmentation of SF5CF3 to yield SF2(+), SF3(+), SF5(+), and CF3(+), where SF3(+) represents the largest branching fraction at 90% of the total bimolecular product formation. The energetics associated with the formation of these ions suggest that molecular Cu-containing products must also be formed in all cases, indicating that the governing reaction mechanisms are more complicated than simple dissociative charge transfer. Production of SF2(+) and SF3(+) are shown to proceed via Cu(+)((3)D) and can be rationalized with a two-step mechanism proceeding through the common intermediate SF3CF3(+). Production of CF3(+) can be explained using this same mechanism but is also energetically possible from Cu(+)((1)D) in a more direct process. Energetic requirements indicate that Cu(+)((1)D) is the sole source of SF5(+) with concomitant formation of CuCF3. Cu(+)((1)S) exhibits adduct formation exclusively, but IMS spectra of the resulting Cu(+)·SF5CF3 suggest that as many as three association structures are formed.