Size-dependent dehydrogenation of ethane by cationic rhodium clusters in the gas phase

The reactivity of cationic rhodium clusters, Rhn+, n = 1–23, with ethane is studied by Fourier transform ion cyclotron resonance mass spectrometry. Single and double dehydrogenation with elimination of molecular hydrogen are the reactions observed. The reaction efficiency and branching ratio are strongly dependent on cluster size. The behavior is attributed to geometric effects, suggesting that dehydrogenation of ethane on cationic rhodium clusters has strong steric requirements.