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 in ion molecule reactions in an FT-ICR-MS cell. CpFe+ does not. The differences in reactivity are rationalized using MO theory. The theoretical calculations show that the electronic structures of the metals in the organometallic complexes are perturbed by the Cp ligand to different degrees. The strong metal 4s character of the LUMOs for CpCo+ and CpNi+ favors the C-H bond activation step, leading to dehydrogenation. Available unoccupied metal 4s orbitals have previously been shown to facilitate C-H and H-H bond activation in reactions with naked metal ions.