Double-Oxygen-Atom Transfer in Reactions of Ce(m) O(2m) (+) (m=2-6) with C(2) H(2).
ABSTRACT 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.