Reactions of the copper dimer, Cu2, in the gas phase

✍ Scribed by Li Lian; Farah Akhtar; Peter A. Hackett; David M. Rayner

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 718 KB
• Volume: 26
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550260110

✦ Synopsis

Abstract

Reactions of Cu~2~ with several small molecules have been studied in the gas phase, under thermalized conditions at room temperature, in a fast‐flow reactor. They fall into one of two categories. Cu~2~ does not react with O~2~, N~2~O, N~2~, H~2~, and CH~4~ at pressures up to 6 torr. This implies bimolecular rate constants of less than 5 × 10^−15^ cm^3^ s^−1^ at 6 torr He. Cu~2~ reacts with CO, NH~3~, C~2~H~4~, and C~3~H~6~ in a manner characteristic of association reactions. Second‐order rate constants for all four of these reagents are dependent on total pressure. The reactions with CO, NH~3~, and C~2~H~4~ are in their low pressure limit at up to 6 torr He buffer gas pressure. The reaction with C~3~H~6~ begins to show fall‐off behavior at pressures above 3 torr. Limiting low‐pressure, third‐order rate constants are 0.66 ± 0.10, 8.8 ± 1.2, 9.3 ± 1.4, and 85 ± 15 × 10^−30^ cm^6^ s^−1^ in He for CO, NH~3~, C~2~H~4~, and C~3~H~6~, respectively. Modeling studies of these rate constants imply that the association complexes are bound by at least 20 kcal mol^−1^ in the case of C~2~H~4~ and C~3~H~6~ and at least 25 kcal mol^−1^ in the other cases. The implications of these results for Cu‐ligand bonding are developed in comparison with existing work on the interactions of these ligands with Cu atoms, larger clusters, and surfaces. © 1994 John Wiley & Sons, Inc.