Double-oxygen-atom transfer in reactions of Ce(m)O(2m)(+) (m=2-6) with C2H2

Cerium oxide cluster cations (Ce(m)O(n)(+), m=2-16; n=2m, 2m ± 1 and 2m ± 2) are prepared by laser ablation and reacted with acetylene (C(2)H(2)) in a fast-flow reactor. A time-of-flight mass spectrometer is used to detect the cluster distribution before and after the reactions. Reactions of stoichiometric Ce(m)O(2m)(+) (m=2-6) with C(2)H(2) produce Ce(m)O(2m-2)(+) clusters, which indicates a "double-oxygen-atom transfer" reaction Ce(m)O(2m)(+) + C(2)H(2) → Ce(m)O(2m-2)(+) + (CHO)(2) (ethanedial). A single-oxygen-atom transfer reaction channel is also identified as Ce(m)O(2m)(+) + C(2)H(2) → Ce(m)O(2m-1)(+) + C(2)H(2)O (at least for m=2 and 3). Density functional theory calculations are performed to study reaction mechanisms of Ce(2)O(4)(+) + C(2)H(2), and the calculated results confirm that both the single- and double-oxygen-atom transfer channels are thermodynamically and kinetically favourable.