Carbon‐Carbon Bond Formation Promoted by “Bare” Lanthanide Cations: The Reactions of Ce+ and La+ with Propene in the Gas Phase

The cationic butadiene and benzene complexes CeC4H6+ and CeC6H6+ are the main products in the reaction of thermalized Ce+ ions with propene in the gas phase, as shown by FT MS. Following the formation of the primary products, i.e. CeCH2+ and CeC3H4+, selective C‐C coupling processes at the lanthanide cation occur as secondary reactions with high efficiency. Ligand‐exchange reactions and comparative collision‐induced dissociation experiments are applied to probe the structures of the final reaction products of this first example of Ce+ gas‐phase chemistry. The reaction of Ce+ with cyclopropane yields a product distribution very similar to the propene reaction; however, it reacts significantly slower. Furthermore, La+ reacts in nearly the same manner with propene as Ce+ which indicates that the single f electron in the latter ion is chemically inert.