Interaction of bismuth oxide cluster cations with alkenes and molecular oxygen: Bi4O6+, a possible reactive center for alkene oxidation

The activation of molecular oxygen by bismuth oxide cluster cations has bee n observed in the presence of unsaturated hydrocarbon molecules. Reactiviti es of gas-phase bismuth oxide cluster cations BixOy+ (x = 3 or 4, y less th an or equal to 7) with hydrocarbons have been studied by measuring scatteri ng cross sections and analyzing products formed under multiple collision co nditions. The integral cross sections for the scattering of the cations Bix Oy+ (x = 3 or 4, y I 7) from argon, alkanes (methane, propane, butane), and alkenes (ethene, propene, l-butene, 1,3-butadiene) have been measured. In particular, the cation Bi4O6+ has a significantly increased cross section f or the scattering from the alkenes as compared to the other oxides Bi4Oy+. The larger total cross section is explained by assuming an increased cross section for reactive collisions, which could be caused by a specific reacti vity of that cation. Products for the reactions of small bismuth oxide clus ter cations BixOy+ (x = 3 or 4) with ethene and propene have been investiga ted by conducting fast-flow reactor experiments. In the series BixOy+ (x = 3 or 4), a simple addition of one or more alkene molecules to the oxide cat ion has been observed. Only Bi4O6+ is special, because it shows addition of alkene and O-2 as shown by the formation of Bi4O8-(alkene)(+) and Bi4O8(al kene)(2)(+).