Dehydrogenation of ethane by CpM+ (M = Fe, Co, Ni) in the gas phase. An FT-ICR-MS study

CpCo+ and CpNi+ (Cp = eta(5)-C5H5, cyclopentadienyl) dehydrogenate ethane i n ion molecule reactions in an FT-ICR-MS cell. CpFe+ does not. The differen ces in reactivity are rationalized using MO theory. The theoretical calcula tions show that the electronic structures of the metals in the organometall ic complexes are perturbed by the Cp ligand to different degrees. The stron g metal 4s character of the LUMOs for CpCo+ and CpNi+ favors the C-H bond a ctivation step, leading to dehydrogenation. Available unoccupied metal 4s o rbitals have previously been shown to facilitate C-H and H-H bond activatio n in reactions with naked metal ions.