The CeO2+ cation: Gas-phase reactivity and electronic structure

''Bare'' CeO2+ ions can be prepared in the gas phase by consecutive oxidation of Ce+ with O-2 and NO2. The ability to activate saturated and unsaturated hydrocarbons is investigated by use of Fourier-transform ion cyclotron resonance mass spectrometry. In the reactions of CeO2+ with linear and branched alkanes C-H bond activation is observed almost exclusively. In contrast, both oxygen-atom transfer and C-H bond activation processes occur when thermalized CeO2+ cations react with simple alkenes and aromatic compounds. C-C bond activation is not observed at all. Insight into the structural and electronic properties of neutral CeO2 and cationic CeO2+ is provided by means of quasirelativistic density-functional and ab initio pseudopotential calculations. They reveal a (2) Sigma(u)(+) ground state for CeO2+ which is best described as a linear cerium dioxide with a resonating pi bond. Finally, we discuss the influence of oxo ligands on the chemistry of the cationic CeOn+ (n = 0-2) species toward hydrocarbons.