ION MOBILITY STUDIES OF PDCN- WHERE ARE THE FULLERENES( CLUSTERS )

Gas-phase ion mobility measurements have been used to study the struct ures and isomerization of PdCn+ (n 10-60) clusters. Non-fullerene isom ers of PdCn+ clusters are similar to those of C-n(+) and MC(n)(+) (M = La and Nb) clusters, and include metal-containing mono- and bicyclic rings and graphite sheets. Neither endohedral nor nonendohedral PdCnfullerene isomers are detected. When collisionally heated, PdCn+ clust ers efficiently convert into fullerenes, but the exothermicity of this process results in the loss of the Pd atom and the formation of a pur e carbon cluster cation. PdCn+ bicyclic rings with an odd number of ca rbon atoms efficiently isomerize into monocyclic rings, while no evide nce is found for this isomerization process for bicyclic rings with an even number of carbon atoms.