Ce_xO_y^- (x = 2-3) + D₂O reactions: Stoichiometric cluster formation from deuteroxide decomposition and anti-Arrhenius behavior

Reactions between small cerium oxide cluster anions and deuterated water were monitored as a function of both water concentration and temperature in order to determine the temperature dependence of the rate constants. Sequential oxidation reactions of the Ce_xO_y^- (x = 2, 3) suboxide cluster anions were found to exhibit anti-Arrhenius behavior, with activation energies ranging from 0 to -18 kJ mol^-1. Direct oxidation of species up to y = x was observed, after which, -OD abstraction and D₂O addition reactions were observed. However, the stoichiometric Ce₂O₄^- and Ce₃O₆^- cluster anions also emerge in reactions between D₂O and the respective precursors, Ce₂O₃D^- and Ce₃O₅D₂^-. Ce₂O₄^- and Ce₃O₆^- product intensities diminish relative to deuteroxide complex intensities with increasing temperature. The kinetics of these reactions are compared to the kinetics of the previously studied Mo_xO_y^- and W_xO_y^- reactions with water, and the possible implications for the reaction mechanisms are discussed.